diff --git a/docs/html/guide/basics/appmodel.jd b/docs/html/guide/basics/appmodel.jd deleted file mode 100644 index 323fc9b3aa914..0000000000000 --- a/docs/html/guide/basics/appmodel.jd +++ /dev/null @@ -1,261 +0,0 @@ -page.title=Application Model -@jd:body -

Android Application Model: Applications, Tasks, Processes, and Threads

- -

In most operating systems, there is a strong 1-to-1 correlation between -the executable image (such as the .exe on Windows) that an application lives in, -the process it runs in, and the icon and application the user interacts with. -In Android these associations are much more fluid, and it is important to -understand how the various pieces can be put together.

- -

Because of the flexible nature of Android applications, there is some -basic terminology that needs to be understood when implementing the -various pieces of an application:

- - - -

Tasks

- -

A key point here is: when the user sees as an "application," what -they are actually dealing with is a task. If you just create a .apk -with a number of activities, one of which is a top-level entry point (via -an {@link android.R.styleable#AndroidManifestIntentFilter intent-filter} for -the action android.intent.action.MAIN and -category android.intent.category.LAUNCHER), then there will indeed -be one task created for your .apk, and any activities you start from there -will also run as part of that task.

- -

A task, then, from the user's perspective your application; and from the -application developer's perspective it is one or more activities the user -has traversed through in that task and not yet closed, or an activity stack. -A new task is created by -starting an activity Intent with the {@link android.content.Intent#FLAG_ACTIVITY_NEW_TASK -Intent.FLAG_ACTIVITY_NEW_TASK} flag; this Intent will be used as the root Intent of -the task, defining what task it is. Any activity started without this flag -will run in the same task as the activity that is starting it (unless that -activity has requested a special launch mode, as discussed later). Tasks can -be re-ordered: if you use FLAG_ACTIVITY_NEW_TASK but there is already a task -running for that Intent, the current task's activity stack will be brought -to the foreground instead of starting a new task.

- -

FLAG_ACTIVITY_NEW_TASK must only be used with care: using it says that, -from the user's perspective, a new application starts at this point. If this -is not the behavior you desire, you should not be creating a new task. In -addition, you should only use the new task flag if it is possible for the user -to navigate from home back to where they are and launch the same Intent as a -new task. Otherwise, if the user presses HOME instead of BACK from the task -you have launched, your task and its activities will be ordered behind the -home screen without a way to return to them.

- -

Task Affinities

- -

In some cases Android needs to know which task an activity belongs to even when -it is not being launched in to a specific task. This is accomplished through -task affinities, which provide a unique static name for the task that one or more -activities are intended to run in. The default task affinity for an activity -is the name of the .apk package name the activity is implemented in. This -provides the normally expected behavior, where all of the activities in a -particular .apk are part of a single application to the user.

- -

When starting a new activity without the -{@link android.content.Intent#FLAG_ACTIVITY_NEW_TASK -Intent.FLAG_ACTIVITY_NEW_TASK} flag, task affinities have no impact on the -task the new activity will run in: it will always run in the task of the -activity that is starting it. However, if the NEW_TASK flag is being used, -then the affinity will be used to determine if a task already exists with -the same affinity. If so, that task will be brought to the front and the -new activity launched at the top of that task.

- -

This behavior is most useful for situations where you must use the -NEW_TASK flag, in particular launching activities from status bar notifications -or home screen shortcuts. The result is that, when the user launches your -application this way, its current task state will be brought to the foreground, -and the activity they now want to look at placed on top of it.

- -

You can assign your own task affinities in your manifest's -{@link android.R.styleable#AndroidManifestApplication application} tag for -all activities in the .apk, or the -{@link android.R.styleable#AndroidManifestActivity activity} tag of -individual activities. Some examples of how this can be used are:

- - -
  • If you are replacing a notification, shortcut, or other such "inner" -activity of an application that can be launched from outside of it, you may -need to explicitly set the taskAffinity of your replacement activity to be -the same as the application you are replacing. For example, if you are -replacing the contacts details view (which the user can make and invoke -shortcuts to), you would want to set the taskAffinity to -"com.android.contacts".
    • - - -

    Launch Modes and Launch Flags

    - -

    The main way you control how activities interact with tasks is through -the activity's -{@link android.R.styleable#AndroidManifestActivity_launchMode launchMode} -attribute and the {@link android.content.Intent#setFlags flags} associated -with an Intent. These two parameters can work together in various ways -to control the outcome of the activity launch, as described in their -associated documentation. Here we will look at some common use cases and -combinations of these parameters.

    - -

    The most common launch mode you will use (besides the default -standard mode) is singleTop. This does not have -an impact on tasks; it just avoids starting the same activity multiple times -on the top of a stack. - -

    The singleTask launch mode has a major -impact on tasks: it causes the activity to always be started in -a new task (or its existing task to be brought to the foreground). Using -this mode requires a lot of care in how you interact with the rest of the -system, as it impacts every path in to the activity. It should only be used -with activities that are front doors to the application (that is, which -support the MAIN action and LAUNCHER category).

    - -

    The singleInstance launch mode is even more specialized, and -should only be used in applications that are implemented entirely as one -activity.

    - -

    A situation you will often run in to is when another entity (such as the -{@link android.app.SearchManager} or {@link android.app.NotificationManager}) -starts one of your activities. In this case, the -{@link android.content.Intent#FLAG_ACTIVITY_NEW_TASK -Intent.FLAG_ACTIVITY_NEW_TASK} flag must be used, because the activity is -being started outside of a task (and the application/task may not even -exist). As described previously, the standard behavior in this situation -is to bring to the foreground the current task matching the new activity's -affinity and start the new activity at the top of it. There are, however, -other types of behavior that you can implement.

    - -

    One common approach is to also use the -{@link android.content.Intent#FLAG_ACTIVITY_CLEAR_TOP -Intent.FLAG_ACTIVITY_CLEAR_TOP} flag in conjunction with NEW_TASK. By doing so, -if your task is already running, then it will be brought to the foreground, -all of the activities on its stack cleared except the root activity, and the -root activity's {@link android.app.Activity#onNewIntent} called with the -Intent being started. Note that the activity often also use the singleTop -or singleTask launch mode when using this approach, so that -the current instance is given the new intent instead of requiring that it -be destroyed and a new instance started.

    - -

    Another approach you can take is to set the notification activity's -android:taskAffinity to the empty string "" (indicating no affinity) -and setting the -{@link android.R.styleable#AndroidManifestActivity_noHistory -android:noHistory} and -{@link android.R.styleable#AndroidManifestActivity_excludeFromRecents -android:excludeFromRecents} attributes. -This approach is useful if you would like the notification -to take the user to a separate activity describing it, rather than return -to the application's task. By specifying these attributes, the activity will -be finished whether the user leaves it with BACK or HOME and it will not -show up in the recent tasks list; if the noHistory attribute -isn't specified, pressing HOME will result in the activity and its task -remaining in the system, possibly with no way to return to it.

    - -

    Be sure to read the documentation on the -{@link android.R.styleable#AndroidManifestActivity_launchMode launchMode attribute} -and the {@link android.content.Intent#setFlags Intent flags} for the details -on these options.

    - -

    Processes

    - -

    In Android, processes are entirely an implementation detail of applications -and not something the user is normally aware of. Their main uses are simply:

    - - - -

    As described previously, the -{@link android.R.styleable#AndroidManifestApplication_process process} attribute -is used to control the process that particular application components run in. -Note that this attribute can not be used to violate security of the system: if -two .apks that are not sharing the same user ID try to run in the same process, -this will not be allowed and different distinct processes will be created for -each of them.

    - -

    See the security document for -more information on these security restrictions.

    - -

    Threads

    - -

    Every process has one or more threads running in it. In most situations, Android -avoids creating additional threads in a process, keeping an application -single-threaded unless it creates its own threads. An important repercussion -of this is that all calls to {@link android.app.Activity}, -{@link android.content.BroadcastReceiver}, and {@link android.app.Service} -instances are made only from the main thread of the process they are running in.

    - -

    Note that a new thread is not created for each -Activity, BroadcastReceiver, Service, or ContentProvider instance: -these application components are instantiated in the desired process (all in the -same process unless otherwise specified), in the main thread of that process. -This means that none of these components (including services) should perform -long or blocking operations (such as networking calls or computation loops) -when called by the system, since this will block -all other components in the process. You can use the standard library -{@link java.lang.Thread} class or Android's {@link android.os.HandlerThread} -convenience class to perform long operations on another thread.

    - -

    There are a few important exceptions to this threading rule:

    - - diff --git a/docs/html/guide/basics/building-blocks.jd b/docs/html/guide/basics/building-blocks.jd deleted file mode 100644 index b8a609e1fcedb..0000000000000 --- a/docs/html/guide/basics/building-blocks.jd +++ /dev/null @@ -1,76 +0,0 @@ -page.title=Building Blocks -@jd:body -

    Android Building Blocks

    - -

    You can think of an Android application as a collection of components, of -various kinds. These components are for the most part quite loosely coupled, -to the degree where you can accurately describe them as a federation of -components rather than a single cohesive application.

    - -

    Generally, these components all run in the same system process. It's -possible (and quite common) to create multiple threads within that process, -and it's also possible to create completely separate child processes if you -need to. Such cases are pretty uncommon though, because Android tries very -hard to make processes transparent to your code.

    - -

    These are the most important parts of the Android APIs:

    - -
    -
    AndroidManifest.xml
    -
    The AndroidManifest.xml file is the control file that tells the system - what to do with all the top-level components (specifically activities, - services, intent receivers, and content providers described below) - you've created. For instance, this is the - "glue" that actually specifies which Intents your Activities receive.
    - -
    {@link android.app.Activity Activities}
    -
    An Activity is, fundamentally, an object that has a life cycle. An - Activity is a chunk of code that does some work; if necessary, that work - can include displaying a UI to the user. It doesn't have to, though - some - Activities never display UIs. Typically, you'll designate one of your - application's Activities as the entry point to your application.
    - - -
    {@link android.view.View Views}
    -
    A View is an object that knows how to draw itself to the screen. - Android user interfaces are comprised of trees of Views. If you want to - perform some custom graphical technique (as you might if you're writing a - game, or building some unusual new user interface widget) then you'd - create a View.
    - - -
    {@link android.content.Intent Intents}
    -
    An Intent is a simple message object that represents an "intention" to - do something. For example, if your application wants to display a web - page, it expresses its "Intent" to view the URI by creating an Intent - instance and handing it off to the system. The system locates some other - piece of code (in this case, the Browser) that knows how to handle that - Intent, and runs it. Intents can also be used to broadcast interesting - events (such as a notification) system-wide.
    - - -
    {@link android.app.Service Services}
    -
    A Service is a body of code that runs in the background. It can run in - its own process, or in the context of another application's process, - depending on its needs. Other components "bind" to a Service and invoke - methods on it via remote procedure calls. An example of a Service is a - media player; even when the user quits the media-selection UI, she - probably still intends for her music to keep playing. A Service keeps the - music going even when the UI has completed.
    - - -
    {@link android.app.NotificationManager Notifications}
    -
    A Notification is a small icon that appears in the status bar. Users - can interact with this icon to receive information. The most well-known - notifications are SMS messages, call history, and voicemail, but - applications can create their own. Notifications are the - strongly-preferred mechanism for alerting the user of something that needs - their attention.
    - -
    {@link android.content.ContentProvider ContentProviders}
    -
    A ContentProvider is a data storehouse that provides access to data on - the device; the classic example is the ContentProvider that's used to - access the user's list of contacts. Your application can access data that - other applications have exposed via a ContentProvider, and you can also - define your own ContentProviders to expose data of your own.
    -
    diff --git a/docs/html/guide/basics/fixme-gs-core-packages.jd b/docs/html/guide/basics/fixme-gs-core-packages.jd deleted file mode 100644 index 52819900a88f5..0000000000000 --- a/docs/html/guide/basics/fixme-gs-core-packages.jd +++ /dev/null @@ -1,92 +0,0 @@ -page.title=Getting Started -@jd:body -

    Getting Started with Android

    - -

    To get started with Android, please read the following sections first:

    -
    -
    Installing the SDK and - Plugin
    -
    How to install the Android SDK and Eclipse plugin.
    -
    Developing and Debugging
    -
    An introduction to developing and debugging Android applications in Eclipse, - plus information on using other IDEs.
    -
    Hello Android
    -
    Writing your first Android Application, the ever popular Hello World, - Android style.
    -
    Anatomy of an App
    -
    A guide to the structure and architecture of an Android - Application. This guide will help you understand the pieces that make up - an Android app.
    -
    Notepad Tutorial
    -
    This tutorial document will lead you through - constructing a real Android Application: A notepad which can create, edit - and delete notes, and covers many of the basic concepts with practical - examples.
    -
    Development Tools
    -
    The - command line tools included with the SDK, what they do, and how to use - them.
    -
    Application Model
    -
    A guide to Applications, Tasks, Processes, and Threads. - These are the elements that define the way your application is run by the - system and presented to the user.
    -
    Application Life Cycle
    -
    The important life-cycle details for - Applications and the Activities running inside of them.
    - -
    - -

    Other Introductory Material

    -

    After reading the sections above, the following Getting Started information is also very useful:

    - - -

    Core Packages

    -

    These are the basic packages that make up the Android SDK for writing -applications. The packages are organized as layers, listed here from -lowest-level to highest.

    - -
    -
    {@link android.util}
    -
    contains various low-level utility classes, such - as specialized container classes, XML utilities, etc.
    -
    {@link android.os}
    -
    provides basic operating system services, message - passing, and inter-process communication.
    -
    {@link android.graphics}
    is the core rendering package.
    -
    {@link android.text}, {@link android.text.method}, {@link - android.text.style}, and {@link android.text.util}
    -
    supply a rich set of - text processing tools, supporting rich text, input methods, etc.
    -
    {@link android.database}
    -
    contains low-level APIs for working with - databases.
    -
    {@link android.content}
    -
    provides various services for accessing data - on the device: applications installed on the device and their associated - resources, and content providers for persistent dynamic data.
    -
    {@link android.view}
    -
    is the core user-interface framework.
    -
    {@link android.widget}
    -
    supplies standard user interface elements - (lists, buttons, layout managers, etc) built from the view package.
    -
    {@link android.app}
    -
    provides the high-level application model, - implemented using Activities.
    -
    - -

    Other Notable Packages

    - -

    These packages provide additional domain-specific features of the Android -platform. They are not necessary for basic application development.

    - -
    -
    {@link android.provider}
    -
    contains definitions for various standard - content providers included with the platform.
    -
    {@link android.telephony}
    -
    provides APIs for interacting with the - device's phone stack.
    -
    {@link android.webkit}
    -
    includes various APIs for working with - web-based content.
    -
    diff --git a/docs/html/guide/basics/index.html b/docs/html/guide/basics/index.html deleted file mode 100644 index 4881acf44581b..0000000000000 --- a/docs/html/guide/basics/index.html +++ /dev/null @@ -1,8 +0,0 @@ - - - - - -click here if you are not redirected. - - \ No newline at end of file diff --git a/docs/html/guide/topics/security/index.jd b/docs/html/guide/topics/security/index.jd deleted file mode 100644 index 775fc036547be..0000000000000 --- a/docs/html/guide/topics/security/index.jd +++ /dev/null @@ -1,65 +0,0 @@ -page.title=Security and Permissions -page.landing=true -page.landing.intro=Android's security architecture gives the user full control over what resources are accessible to each app, protecting the system itself and all apps in it. Learn how to use system permissions to request access to the resources your app needs and design your app for optimal security. -page.landing.image= - -@jd:body - -
    - -
    -

    Blog Articles

    - -
    - -
    - -
    - -
    -

    Accessibility: Are You Serving All Your Users?

    -

    In the upcoming weeks, some of the older Client Login authentication keys will expire. - If you generated the token you’re currently using to authenticate with the C2DM servers before October 2011, it will stop working.

    - -

    Android C2DM — Client Login key expiration

    -

    Accessibility is about making sure that Android users who have limited vision or other physical impairments can use your application just as well

    - -

    A Faster Emulator with Better Hardware Support

    -

    The Android emulator is a key tool for Android developers in building and testing their apps. - As the power and diversity of Android devices has grown quickly, it’s been hard for the emulator keep pace.

    - - More » -
    -
    -
    - -
    -

    Training

    - -
    - -
    - -
    - -
    -

    Managing the Activity Lifecycle

    -

    This class explains important lifecycle callback methods that each Activity - instance receives and how you can use them so your activity does what the user expects and does not consume system - resources when your activity doesn't need them.

    - -

    Supporting Different Devices

    -

    This class teaches you how to use basic platform features that leverage alternative - resources and other features so your app can provide an optimized user experience on a variety of Android-compatible devices, - using a single application package (APK).

    - -

    Sharing Content

    -

    This class covers some common ways you can send and receive content between - applications using Intent APIs and the ActionProvider object.

    - - More » -
    -
    -
    - -
    \ No newline at end of file diff --git a/docs/html/guide/topics/security/security.jd b/docs/html/guide/topics/security/security.jd deleted file mode 100644 index 9cdccaeb0a0b1..0000000000000 --- a/docs/html/guide/topics/security/security.jd +++ /dev/null @@ -1,767 +0,0 @@ -page.title=Designing for Security -@jd:body - -
    -
    -

    In this document

    -
      -
    1. Using Davlik Code
      2. -
    2. Using Native Code
      3. -
    3. Storing Data
      4. -
    4. Using IPC
      5. -
    5. Using Permissions
      6. -
    6. Using Networking
      7. -
    7. Dynamically Loading Code
      8. -
    8. Performing Input Validation
      9. -
    9. Handling User Data
      10. -
    10. Using Cryptography
      11. -
    -

    See also

    -
      -
    1. Android -Security Overview
      2. -
    2. Android Security -And Permissions
      3. -
    -
    -

    Android was designed so that most developers will be able to build -applications using the default settings and not be confronted with difficult -decisions about security. Android also has a number of security features built -into the operating system that significantly reduce the frequency and impact of -application security issues.

    - -

    Some of the security features that help developers build secure applications -include: -

    - -

    Nevertheless, it is important for developers to be familiar with Android -security best practices to make sure they take advantage of these capabilities -and to reduce the likelihood of inadvertently introducing security issues that -can affect their applications.

    - -

    This document is organized around common APIs and development techniques -that can have security implications for your application and its users. As -these best practices are constantly evolving, we recommend you check back -occasionally throughout your application development process.

    - - -

    Using Dalvik Code

    -

    Writing secure code that runs in virtual machines is a well-studied topic -and many of the issues are not specific to Android. Rather than attempting to -rehash these topics, we’d recommend that you familiarize yourself with the -existing literature. Two of the more popular resources are: -

    - -

    This document is focused on the areas which are Android specific and/or -different from other environments. For developers experienced with VM -programming in other environments, there are two broad issues that may be -different about writing apps for Android: -

    - - -

    Using Native Code

    - -

    In general, we encourage developers to use the Android SDK for most -application development, rather than using native code. Applications built -with native code are more complex, less portable, and more like to include -common memory corruption errors such as buffer overflows.

    - -

    Android is built using the Linux kernel and being familiar with Linux -development security best practices is especially useful if you are going to -use native code. This document is too short to discuss all of those best -practices, but one of the most popular resources is “Secure Programming for -Linux and Unix HOWTO”, available at -http://www.dwheeler.com/secure-programs.

    - -

    An important difference between Android and most Linux environments is the -Application Sandbox. On Android, all applications run in the Application -Sandbox, including those written with native code. At the most basic level, a -good way to think about it for developers familiar with Linux is to know that -every application is given a unique UID with very limited permissions. This is -discussed in more detail in the Android Security -Overview and you should be familiar with application permissions even if -you are using native code.

    - - -

    Storing Data

    - -

    Using internal files

    - -

    By default, files created on internal -storage are only accessible to the application that created the file. This -protection is implemented by Android and is sufficient for most -applications.

    - -

    Use of -world writable or world -readable files for IPC is discouraged because it does not provide -the ability to limit data access to particular applications, nor does it -provide any control on data format. As an alternative, you might consider using -a ContentProvider which provides read and write permissions, and can make -dynamic permission grants on a case-by-case basis.

    - -

    To provide additional protection for sensitive data, some applications -choose to encrypt local files using a key that is not accessible to the -application. (For example, a key can be placed in a {@link java.security.KeyStore} and -protected with a user password that is not stored on the device). While this -does not protect data from a root compromise that can monitor the user -inputting the password, it can provide protection for a lost device without file system -encryption.

    - -

    Using external storage

    - -

    Files created on external -storage, such as SD Cards, are globally readable and writable. Since -external storage can be removed by the user and also modified by any -application, applications should not store sensitive information using -external storage.

    - -

    As with data from any untrusted source, applications should perform input -validation when handling data from external storage (see Input Validation -section). We strongly recommend that applications not store executables or -class files on external storage prior to dynamic loading. If an application -does retrieve executable files from external storage they should be signed and -cryptographically verified prior to dynamic loading.

    - -

    Using content providers

    - -

    ContentProviders provide a structured storage mechanism that can be limited -to your own application, or exported to allow access by other applications. By -default, a - -ContentProvider is -exported - for use by other applications. If you do not intend to provide other -applications with access to your - -ContentProvider, mark them as -android:exported=false in the application manifest.

    - -

    When creating a -ContentProvider - that will be exported for use by other applications, you can specify -a single -permission - for reading and writing, or distinct permissions for reading and writing -within the manifest. We recommend that you limit your permissions to those -required to accomplish the task at hand. Keep in mind that it’s usually -easier to add permissions later to expose new functionality than it is to take -them away and break existing users.

    - -

    If you are using a - -ContentProvider for sharing data between applications built by the -same developer, it is preferable to use -signature -level permissions. Signature permissions do not require user confirmation, -so they provide a better user experience and more controlled access to the - - -ContentProvider.

    - -

    ContentProviders can also provide more granular access by declaring the -grantUriPermissions element and using the FLAG_GRANT_READ_URI_PERMISSION -and FLAG_GRANT_WRITE_URI_PERMISSION -flags in the Intent object -that activates the component. The scope of these permissions can be further -limited by the -grant-uri-permission element.

    - -

    When accessing a - -ContentProvider, use parameterized query methods such as -query(), update(), and delete() to avoid -potential SQL -Injection from untrusted data. Note that using parameterized methods is not -sufficient if the selection is built by concatenating user data -prior to submitting it to the method.

    - -

    Do not have a false sense of security about the write permission. Consider -that the write permission allows SQL statements which make it possible for some -data to be confirmed using creative WHERE clauses and parsing the -results. For example, an attacker might probe for presence of a specific phone -number in a call-log by modifying a row only if that phone number already -exists. If the content provider data has predictable structure, the write -permission may be equivalent to providing both reading and writing.

    - - -

    Using Interprocess Communication (IPC)

    - -

    Some Android applications attempt to implement IPC using traditional Linux -techniques such as network sockets and shared files. We strongly encourage the -use of Android system functionality for IPC such as Intents, Binders, Services, -and Receivers. The Android IPC mechanisms allow you to verify the identity of -the application connecting to your IPC and set security policy for each IPC -mechanism.

    - -

    Many of the security elements are shared across IPC mechanisms. -Broadcast Receivers, -Activities, and -Services are all declared in the application manifest. If your IPC mechanism is -not intended for use by other applications, set the {@code android:exported} -property to false. This is useful for applications that consist of multiple processes -within the same UID, or if you decide late in development that you do not -actually want to expose functionality as IPC but you don’t want to rewrite -the code.

    - -

    If your IPC is intended to be accessible to other applications, you can -apply a security policy by using the -Permission tag. If IPC is between applications built by the same developer, -it is preferable to use signature -level permissions. Signature permissions do not require user confirmation, -so they provide a better user experience and more controlled access to the IPC -mechanism.

    - -

    One area that can introduce confusion is the use of intent filters. Note -that Intent filters should not be considered a security feature -- components -can be invoked directly and may not have data that would conform to the intent -filter. You should perform input validation within your intent receiver to -confirm that it is properly formatted for the invoked receiver, service, or -activity.

    - -

    Using intents

    - -

    Intents are the preferred mechanism for asynchronous IPC in Android. -Depending on your application requirements, you might use sendBroadcast(), -sendOrderedBroadcast(), -or direct an intent to a specific application component.

    - -

    Note that ordered broadcasts can be “consumed” by a recipient, so they -may not be delivered to all applications. If you are sending an Intent where -delivery to a specific receiver is required, the intent must be delivered -directly to the receiver.

    - -

    Senders of an intent can verify that the recipient has a permission -specifying a non-Null Permission upon sending. Only applications with that -Permission will receive the intent. If data within a broadcast intent may be -sensitive, you should consider applying a permission to make sure that -malicious applications cannot register to receive those messages without -appropriate permissions. In those circumstances, you may also consider -invoking the receiver directly, rather than raising a broadcast.

    - -

    Using binder and AIDL interfaces

    - -

    Binders are the -preferred mechanism for RPC-style IPC in Android. They provide a well-defined -interface that enables mutual authentication of the endpoints, if required.

    - -

    We strongly encourage designing interfaces in a manner that does not require -interface specific permission checks. Binders are not declared within the -application manifest, and therefore you cannot apply declarative permissions -directly to a Binder. Binders generally inherit permissions declared in the -application manifest for the Service or Activity within which they are -implemented. If you are creating an interface that requires authentication -and/or access controls on a specific binder interface, those controls must be -explicitly added as code in the interface.

    - -

    If providing an interface that does require access controls, use checkCallingPermission() -to verify whether the -caller of the Binder has a required permission. This is especially important -before accessing a Service on behalf of the caller, as the identify of your -application is passed to other interfaces. If invoking an interface provided -by a Service, the bindService() - invocation may fail if you do not have permission to access the given Service. - If calling an interface provided locally by your own application, it may be -useful to use the -clearCallingIdentity() to satisfy internal security checks.

    - -

    Using broadcast receivers

    - -

    Broadcast receivers are used to handle asynchronous requests initiated via -an intent.

    - -

    By default, receivers are exported and can be invoked by any other -application. If your -BroadcastReceivers is intended for use by other applications, you -may want to apply security permissions to receivers using the -<receiver> element within the application manifest. This will -prevent applications without appropriate permissions from sending an intent to -the -BroadcastReceivers.

    - -

    Using Services

    - -

    Services are often used to supply functionality for other applications to -use. Each service class must have a corresponding declaration in its -package's AndroidManifest.xml.

    - -

    By default, Services are exported and can be invoked by any other -application. Services can be protected using the {@code android:permission} -attribute -within the manifest’s -<service> tag. By doing so, other applications will need to declare -a corresponding <uses-permission> - element in their own manifest to be -able to start, stop, or bind to the service.

    - -

    A Service can protect individual IPC calls into it with permissions, by -calling checkCallingPermission() -before executing -the implementation of that call. We generally recommend using the -declarative permissions in the manifest, since those are less prone to -oversight.

    - -

    Using Activities

    - -

    Activities are most often used for providing the core user-facing -functionality of an application. By default, Activities are exported and -invokable by other applications only if they have an intent filter or binder -declared. In general, we recommend that you specifically declare a Receiver or -Service to handle IPC, since this modular approach reduces the risk of exposing -functionality that is not intended for use by other applications.

    - -

    If you do expose an Activity for purposes of IPC, the android:permission -attribute in the -<activity> declaration in the application manifest can be used to -restrict access to only those applications which have the stated -permissions.

    - - -

    Using Permissions

    - -

    Requesting Permissions

    - -

    We recommend minimizing the number of permissions requested by an -application. Not having access to sensitive permissions reduces the risk of -inadvertently misusing those permissions, can improve user adoption, and makes -applications less attractive targets for attackers.

    - -

    If it is possible to design your application in a way that does not require -a permission, that is preferable. For example, rather than requesting access -to device information to create an identifier, create a GUID for your application. -(This specific example is also discussed in Handling User Data) Or, rather than -using external storage, store data in your application directory.

    - -

    If a permission is not required, do not request it. This sounds simple, but -there has been quite a bit of research into the frequency of over-requesting -permissions. If you’re interested in the subject you might start with this -research paper published by U.C. Berkeley: -http://www.eecs.berkeley.edu/Pubs/TechRpts/2011/EECS-2011-48.pdf

    - -

    In addition to requesting permissions, your application can use permissions -to protect IPC that is security sensitive and will be exposed to other -applications -- such as a -ContentProvider. In general, we recommend using access controls -other than user confirmed permissions where possible since permissions can -be confusing for users. For example, consider using the signature -protection level on permissions for IPC communication between applications -provided by a single developer.

    - -

    Do not cause permission re-delegation. This occurs when an app exposes data -over IPC that is only available because it has a specific permission, but does -not require that permission of any clients of it’s IPC interface. More -details on the potential impacts, and frequency of this type of problem is -provided in this research paper published at USENIX: http://www.cs.be -rkeley.edu/~afelt/felt_usenixsec2011.pdf

    - -

    Creating Permissions

    - -

    Generally, you should strive to create as few permissions as possible while -satisfying your security requirements. Creating a new permission is relatively -uncommon for most applications, since system-defined -permissions cover many situations. Where appropriate, -perform access checks using existing permissions.

    - -

    If you must create a new permission, consider whether you can accomplish -your task with a Signature permission. Signature permissions are transparent -to the user and only allow access by applications signed by the same developer -as application performing the permission check. If you create a Dangerous -permission, then the user needs to decide whether to install the application. -This can be confusing for other developers, as well as for users.

    - -

    If you create a Dangerous permission, there are a number of complexities -that you need to consider. -

    - -

    Each of these poses a significant non-technical challenge for an application -developer, which is why we discourage the use of Dangerous permission.

    - - -

    Using Networking

    - -

    Using IP Networking

    - -

    Networking on Android is not significantly different from Linux -environments. The key consideration is making sure that appropriate protocols -are used for sensitive data, such as HTTPS for -web traffic. We prefer use of HTTPS over HTTP anywhere that HTTPS is -supported on the server, since mobile devices frequently connect on networks -that are not secured, such as public WiFi hotspots.

    - -

    Authenticated, encrypted socket-level communication can be easily -implemented using the SSLSocket -class. Given the frequency with which Android devices connect to unsecured -wireless networks using WiFi, the use of secure networking is strongly -encouraged for all applications.

    - -

    We have seen some applications use localhost network ports for -handling sensitive IPC. We discourage this approach since these interfaces are -accessible by other applications on the device. Instead, use an Android IPC -mechanism where authentication is possible such as a Service and Binder. (Even -worse than using loopback is to bind to INADDR_ANY since then your application -may receive requests from anywhere. We’ve seen that, too.)

    - -

    Also, one common issue that warrants repeating is to make sure that you do -not trust data downloaded from HTTP or other insecure protocols. This includes -validation of input in WebView and -any responses to intents issued against HTTP.

    - -

    Using Telephony Networking

    - -

    SMS is the telephony protocol most frequently used by Android developers. -Developers should keep in mind that this protocol was primarily designed for -user-to-user communication and is not well-suited for some application -purposes. Due to the limitations of SMS, we strongly recommend the use of C2DM and IP networking for -sending data messages to devices.

    - -

    Many developers do not realize that SMS is not encrypted or strongly -authenticated on the network or on the device. In particular, any SMS receiver -should expect that a malicious user may have sent the SMS to your application --- do not rely on unauthenticated SMS data to perform sensitive commands. -Also, you should be aware that SMS may be subject to spoofing and/or -interception on the network. On the Android-powered device itself, SMS -messages are transmitted as Broadcast intents, so they may be read or captured -by other applications that have the READ_SMS permission.

    - - -

    Dynamically Loading Code

    - -

    We strongly discourage loading code from outside of the application APK. -Doing so significantly increases the likelihood of application compromise due -to code injection or code tampering. It also adds complexity around version -management and application testing. Finally, it can make it impossible to -verify the behavior of an application, so it may be prohibited in some -environments.

    - -

    If your application does dynamically load code, the most important thing to -keep in mind about dynamically loaded code is that it runs with the same -security permissions as the application APK. The user made a decision to -install your application based on your identity, and they are expecting that -you provide any code run within the application, including code that is -dynamically loaded.

    - -

    The major security risk associated with dynamically loading code is that the -code needs to come from a verifiable source. If the modules are included -directly within your APK, then they cannot be modified by other applications. -This is true whether the code is a native library or a class being loaded using - -DexClassLoader. We have seen many instances of applications -attempting to load code from insecure locations, such as downloaded from the -network over unencrypted protocols or from world writable locations such as -external storage. These locations could allow someone on the network to modify -the content in transit, or another application on a users device to modify the -content, respectively.

    - - -

    Using WebView

    - -

    Since WebView consumes web content that can include HTML and JavaScript, -improper use can introduce common web security issues such as cross-site-scripting (JavaScript injection). Android includes a number of mechanisms to reduce -the scope of these potential issues by limiting the capability of WebView to -the minimum functionality required by your application.

    - -

    If your application does not directly use JavaScript within a WebView, do -not call - -setJavaScriptEnabled(). We have seen this method invoked -in sample code that might be repurposed in production application -- so -remove it if necessary. By default, WebView does -not execute JavaScript so cross-site-scripting is not possible.

    - -

    Use addJavaScriptInterface() with -particular care because it allows JavaScript to invoke operations that are -normally reserved for Android applications. Only expose addJavaScriptInterface() to -sources from which all input is trustworthy. If untrusted input is allowed, -untrusted JavaScript may be able to invoke Android methods. In general, we -recommend only exposing addJavaScriptInterface() to -JavaScript that is contained within your application APK.

    - -

    Do not trust information downloaded over HTTP, use HTTPS instead. Even if -you are connecting only to a single website that you trust or control, HTTP is -subject to MiTM attacks -and interception of data. Sensitive capabilities using addJavaScriptInterface() should -not ever be exposed to unverified script downloaded over HTTP. Note that even -with the use of HTTPS, -addJavaScriptInterface() -increases the attack surface of your application to include the server -infrastructure and all CAs trusted by the Android-powered device.

    - -

    If your application accesses sensitive data with a WebView, you -may want to use the -clearCache() method to delete any files stored locally. Server side -headers like no-cache can also be used to indicate that an application should -not cache particular content.

    - - -

    Performing Input Validation

    - -

    Insufficient input validation is one of the most common security problems -affecting applications, regardless of what platform they run on. Android does -have platform-level countermeasures that reduce the exposure of applications to -input validation issues, you should use those features where possible. Also -note that selection of type-safe languages tends to reduce the likelihood of -input validation issues. We strongly recommend building your applications with -the Android SDK.

    - -

    If you are using native code, then any data read from files, received over -the network, or received from an IPC has the potential to introduce a security -issue. The most common problems are buffer overflows, use after -free, and off-by-one errors. -Android provides a number of technologies like ASLR and DEP that reduce the -exploitability of these errors, but they do not solve the underlying problem. -These can be prevented by careful handling of pointers and managing of -buffers.

    - -

    Dynamic, string based languages such as JavaScript and SQL are also subject -to input validation problems due to escape characters and script injection.

    - -

    If you are using data within queries that are submitted to SQL Database or a -Content Provider, SQL Injection may be an issue. The best defense is to use -parameterized queries, as is discussed in the ContentProviders section. -Limiting permissions to read-only or write-only can also reduce the potential -for harm related to SQL Injection.

    - -

    If you are using WebView, then -you must consider the possibility of XSS. If your application does not -directly use JavaScript within a WebView, do -not call setJavaScriptEnabled() and XSS is no longer possible. If you must -enable JavaScript then the WebView section provides other security best -practices.

    - -

    If you cannot use the security features above, we strongly recommend the use -of well-structured data formats and verifying that the data conforms to the -expected format. While blacklisting of characters or character-replacement can -be an effective strategy, these techniques are error-prone in practice and -should be avoided when possible.

    - - -

    Handling User Data

    - -

    In general, the best approach is to minimize use of APIs that access -sensitive or personal user data. If you have access to data and can avoid -storing or transmitting the information, do not store or transmit the data. -Finally, consider if there is a way that your application logic can be -implemented using a hash or non-reversible form of the data. For example, your -application might use the hash of an an email address as a primary key, to -avoid transmitting or storing the email address. This reduces the chances of -inadvertently exposing data, and it also reduces the chance of attackers -attempting to exploit your application.

    - -

    If your application accesses personal information such as passwords or -usernames, keep in mind that some jurisdictions may require you to provide a -privacy policy explaining your use and storage of that data. So following the -security best practice of minimizing access to user data may also simplify -compliance.

    - -

    You should also consider whether your application might be inadvertently -exposing personal information to other parties such as third-party components -for advertising or third-party services used by your application. If you don't -know why a component or service requires a personal information, don’t -provide it. In general, reducing the access to personal information by your -application will reduce the potential for problems in this area.

    - -

    If access to sensitive data is required, evaluate whether that information -must be transmitted to a server, or whether the operation can be performed on -the client. Consider running any code using sensitive data on the client to -avoid transmitting user data.

    - -

    Also, make sure that you do not inadvertently expose user data to other -application on the device through overly permissive IPC, world writable files, -or network sockets. This is a special case of permission redelegation, -discussed in the Requesting Permissions section.

    - -

    If a GUID is required, create a large, unique number and store it. Do not -use phone identifiers such as the phone number or IMEI which may be associated -with personal information. This topic is discussed in more detail in the Android Developer Blog.

    - -

    Application developers should be careful writing to on-device logs. -In Android, logs are a shared resource, and are available -to an application with the - -READ_LOGS permission. Even though the phone log data -is temporary and erased on reboot, inappropriate logging of user information -could inadvertently leak user data to other applications.

    - - -

    Handling Credentials

    - -

    In general, we recommend minimizing the frequency of asking for user -credentials -- to make phishing attacks more conspicuous, and less likely to be -successful. Instead use an authorization token and refresh it.

    - -

    Where possible, username and password should not be stored on the device. -Instead, perform initial authentication using the username and password -supplied by the user, and then use a short-lived, service-specific -authorization token.

    - -

    Services that will be accessible to multiple applications should be accessed -using - -AccountManager. If possible, use the -AccountManager class to invoke a cloud-based service and do not store -passwords on the device.

    - -

    After using -AccountManager to retrieve an Account, check the CREATOR - before passing in any credentials, so that you do not inadvertently pass -credentials to the wrong application.

    - -

    If credentials are to be used only by applications that you create, then you -can verify the application which accesses the -AccountManager using checkSignature(). -Alternatively, if only one application will use the credential, you might use a -{@link java.security.KeyStore} for -storage.

    - - -

    Using Cryptography

    - -

    In addition to providing data isolation, supporting full-filesystem -encryption, and providing secure communications channels Android provides a -wide array of algorithms for protecting data using cryptography.

    - -

    In general, try to use the highest level of pre-existing framework -implementation that can support your use case. If you need to securely -retrieve a file from a known location, a simple HTTPS URI may be adequate and -require no knowledge of cryptography on your part. If you need a secure -tunnel, consider using - -HttpsURLConnection or SSLSocket, -rather than writing your own protocol.

    - -

    If you do find yourself needing to implement your own protocol, we strongly -recommend that you not implement your own cryptographic algorithms. Use -existing cryptographic algorithms such as those in the implementation of AES or -RSA provided in the Cipher class.

    - -

    Use a secure random number generator ( - -SecureRandom) to initialize any cryptographic keys ( -KeyGenerator). Use of a key that is not generated with a secure random -number generator significantly weakens the strength of the algorithm, and may -allow offline attacks.

    - -

    If you need to store a key for repeated use, use a mechanism like {@link java.security.KeyStore} that -provides a mechanism for long term storage and retrieval of cryptographic -keys.

    - -

    Conclusion

    - -

    Android provides developers with the ability to design applications with a -broad range of security requirements. These best practices will help you make -sure that your application takes advantage of the security benefits provided by -the platform.

    - -

    You can receive more information on these topics and discuss security best -practices with other developers in the Android Security -Discuss Google Group

    diff --git a/docs/html/guide/topics/ui/layout-objects.jd b/docs/html/guide/topics/ui/layout-objects.jd deleted file mode 100644 index 1d15ad60c0799..0000000000000 --- a/docs/html/guide/topics/ui/layout-objects.jd +++ /dev/null @@ -1,6 +0,0 @@ -page.title=Layouts -parent.title=User Interface -parent.link=index.html -@jd:body - -

    You should have been redirected to Layouts.

    \ No newline at end of file diff --git a/docs/html/guide/topics/ui/notifiers/index.jd b/docs/html/guide/topics/ui/notifiers/index.jd deleted file mode 100644 index caf0df70edd11..0000000000000 --- a/docs/html/guide/topics/ui/notifiers/index.jd +++ /dev/null @@ -1,92 +0,0 @@ -page.title=Notifications -parent.title=User Interface -parent.link=../index.html -@jd:body - -

    Several types of situations may arise that require you to notify the user -about an event that occurs in your application. Some events require the user to respond -and others do not. For example:

    - - -

    Each of these notification tasks can be achieved using a different technique:

    - - -

    This document summarizes each of these techniques for notifying the user and includes -links to full documentation.

    - - -

    Toast Notification

    - - - -

    A toast notification is a message that pops up on the surface of the window. -It only fills the amount of space required for the message and the user's current -activity remains visible and interactive. The notification automatically fades in and -out, and does not accept interaction events. Because a toast can be created from a background -{@link android.app.Service}, it appears even if the application isn't visible.

    - -

    A toast is best for short text messages, such as "File saved," -when you're fairly certain the user is paying attention -to the screen. A toast can not accept user interaction events; if you'd like -the user to respond and take action, consider using a -Status Notification instead.

    - -

    For more information, refer to Toast Notifications.

    - - -

    Status Notification

    - - - -

    A status notification adds an icon to the system's status bar -(with an optional ticker-text message) and an expanded message in the "Notifications" window. -When the user selects the expanded message, Android fires an -{@link android.content.Intent} that is defined by the notification (usually to launch an -{@link android.app.Activity}). -You can also configure the notification to alert the user with a sound, a vibration, and flashing -lights on the device.

    - -

    This kind of notification is ideal when your application is working in -a background {@link android.app.Service} and needs to -notify the user about an event. If you need to alert the user about an event that occurs -while your Activity is still in focus, consider using a -Dialog Notification instead.

    - -

    For more information, refer to -Status Notifications.

    - - -

    Dialog Notification

    - - - -

    A dialog is usually a small window that appears in front of the current Activity. -The underlying Activity loses focus and the dialog accepts all user interaction. -Dialogs are normally used -for notifications and short activities that directly relate to the application in progress.

    - -

    You should use a dialog when you need to show a progress bar or a short -message that requires confirmation from the user (such as an alert with "OK" and "Cancel" buttons). -You can use also use dialogs as integral components -in your application's UI and for other purposes besides notifications. -For a complete discussion on all the available types of dialogs, -including its uses for notifications, refer to -Dialogs.

    - - - diff --git a/docs/html/sdk/installing/next.jd b/docs/html/sdk/installing/next.jd deleted file mode 100644 index cb974a4555a06..0000000000000 --- a/docs/html/sdk/installing/next.jd +++ /dev/null @@ -1,51 +0,0 @@ -page.title=Next Steps - -@jd:body - - -

    Now that you've installed the Android SDK, here are are a few ways to learn Android -and start developing:

    - -

    Start coding

    - - - -

    Learn how to design your app

    - - - -

    Read up on the API framework

    - - - -

    Explore the development tools

    - - - -

    Explore some code

    - -