am 5bde4bc5: am 1cd65b30: delete a few unused/obsolete files and add redirects

* commit '5bde4bc5c7ea442a5940658d17a03f1a5010450c':
  delete a few unused/obsolete files and add redirects
This commit is contained in:
Scott Main
2013-05-06 17:18:57 -07:00
committed by Android Git Automerger
7 changed files with 8 additions and 662 deletions

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@@ -9,6 +9,12 @@ redirects:
to: /about/versions/android-\1
pattern: True
- from: /about/versions/index.html
to: /about/index.html
- from: /about/versions/api-levels.html
to: /guide/topics/manifest/uses-sdk-element.html#ApiLevels
- from: /sdk/adding-components.html
to: /sdk/exploring.html

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@@ -1,34 +0,0 @@
page.title=Flexible Framework
walkthru=1
@jd:body
<style>
blockquote {
color:#9933CC;
}
</style>
<blockquote>Android's flexible framework means it runs on more devices and reaches more
users</blockquote>
<p>Android powers millions of devices around the world and in a variety of form-factors. The Android
framework is specially built to run apps on more than just one screen size and hardware
configuration. As an app developer, Android's scale and variety offers you the potential to quickly
reach millions of users.</p>
<p>Android apps are flexible and easily adapt to the device on which they are running. Although the
system scales your assets when necessary, you can provide alternative app resources that are
optimized for specific device categories, such as the screen size and density. Android applies the
appropriate resources when running your app, based on the current devices configuration.</p>
<blockquote>You're in control of which devices can install your app</blockquote>
<p>Some devices provide a different user experience when using apps, but youre always in control of
how your app behaves on each device. If you publish your app on Google Play, you also have
control over which kinds of devices are allowed to install your app and you can closely control how
your app is distributed.</p>
<p>Every device that includes Google Play has been certified compatible. This means that
the device has passed a rigorous test suite to ensure that the device uses a version of Android that
supports all the platform APIs and will successfully run your app.</p>

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@@ -1,62 +0,0 @@
page.title=Open Marketplace
walkthru=1
@jd:body
<style>
blockquote {
color:#9933CC;
}
</style>
<p>Android offers an open distribution model, not a walled garden. Once youve developed an
app for Android and want to distribute it, you have choice.</p>
<p>Your final application is contained in an APK file that you can make available to users any
way you want. For example, you can upload it to your own web site to allow visitors to
install it onto their devices. More often, youll want to use a trusted
marketplace where users can discover and search for your apps.</p>
<p>How you choose to distribute your app affects precisely how many users your app will reach. Which
distribution provider you choose also affects the kinds of services available to you as a publisher,
such as licensing and in-app billing APIs, user bug reports, installation analytics, marketing
services, and more.</p>
<p>Among your choices is Google Play, the premier marketplace for selling and distributing apps
to Android users around the world. When you publish an app on Google Play, you reach hundreds of
millions of customers in over 130 countries.</p>
<h3>Your business, your customers</h3>
<blockquote>Google Play makes your apps available to your customers
immediately</blockquote>
<p>As an open marketplace, Google Play puts you in control of your business and makes it easy for
you to manage how you sell your products. You can publish whenever you want, as often as you want,
and to the exact set of customers you want.</p>
<h3>Visibility for your apps</h3>
<p>Beyond growing your customer base, Google Play helps you build visibility and engagement across
your apps and brand. As your apps rise in popularity, Google Play gives you higher placement in
weekly "top" lists and offers promotional slots in curated collections. You can engage customers
using rich, colorful product pages that feature app screenshots, videos, and user reviews, as well
as cross-marketing links to your other products.</p>
<h3>Flexible monetizing and distribution</h3>
<blockquote class="right">You can distribute
your apps free or priced and you can sell in-app products for additional revenue</blockquote>
<p>Google Play offers a choice of monetizing options to meet your business needs. You control the
pricing of your apps and in-app products&mdash;you can set and change prices at any time, even
individually in local currencies around the world. On purchase, Google Play handles transactions in
the buyers currency and makes payouts in your own currency.</p>
<p>After publishing, you can manage the distribution of your app. You can distribute broadly to all
markets and devices or focus on specific segments, devices, or ranges of hardware capabilities.
Google Play provides the tools for controlling distribution and ensures that your app is available
only to the users who you are targeting.</p>

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@@ -1,421 +0,0 @@
page.title=Android API Levels
@jd:body
<div id="qv-wrapper">
<div id="qv">
<h2>In this document</h2>
<ol>
<li><a href="#intro">What is API Level?</a></li>
<li><a href="#uses">Uses of API Level in Android</a></li>
<li><a href="#considerations">Development Considerations</a>
<ol>
<li><a href="#fc">Application forward compatibility</a></li>
<li><a href="#bc">Application backward compatibility</a></li>
<li><a href="#platform">Selecting a platform version and API Level</a></li>
<li><a href="#apilevel">Declaring a minimum API Level</a></li>
<li><a href="#testing">Testing against higher API Levels</a></li>
</ol>
</li>
<li><a href="#provisional">Using a Provisional API Level</a></li>
<li><a href="#filtering">Filtering the Documentation</a></li>
</ol>
<h2>See also</h2>
<ol>
<li><a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html">&lt;uses-sdk&gt;</a> manifest element</li>
</ol>
</div>
</div>
<p>As you develop your application on Android, it's useful to understand the
platform's general approach to API change management. It's also important to
understand the API Level identifier and the role it plays in ensuring your
application's compatibility with devices on which it may be installed. </p>
<p>The sections below provide information about API Level and how it affects
your applications. </p>
<p>For information about how to use the "Filter by API Level" control
available in the API reference documentation, see
<a href="#filtering">Filtering the documentation</a> at the
end of this document. </p>
<h2 id="intro">What is API Level?</h2>
<p>API Level is an integer value that uniquely identifies the framework API
revision offered by a version of the Android platform.</p>
<p>The Android platform provides a framework API that applications can use to
interact with the underlying Android system. The framework API consists of:</p>
<ul>
<li>A core set of packages and classes</li>
<li>A set of XML elements and attributes for declaring a manifest file</li>
<li>A set of XML elements and attributes for declaring and accessing resources</li>
<li>A set of Intents</li>
<li>A set of permissions that applications can request, as well as permission
enforcements included in the system</li>
</ul>
<p>Each successive version of the Android platform can include updates to the
Android application framework API that it delivers. </p>
<p>Updates to the framework API are designed so that the new API remains
compatible with earlier versions of the API. That is, most changes in the API
are additive and introduce new or replacement functionality. As parts of the API
are upgraded, the older replaced parts are deprecated but are not removed, so
that existing applications can still use them. In a very small number of cases,
parts of the API may be modified or removed, although typically such changes are
only needed to ensure API robustness and application or system security. All
other API parts from earlier revisions are carried forward without
modification.</p>
<p>The framework API that an Android platform delivers is specified using an
integer identifier called "API Level". Each Android platform version supports
exactly one API Level, although support is implicit for all earlier API Levels
(down to API Level 1). The initial release of the Android platform provided
API Level 1 and subsequent releases have incremented the API Level.</p>
<p>The following table specifies the API Level supported by each version of the
Android platform.</p>
<table>
<tr><th>Platform Version</th><th>API Level</th><th>VERSION_CODE</th><th>Notes</th></tr>
<tr><td><a href="{@docRoot}about/versions/android-4.0.3.html">Android 4.0.3</a></td>
<td><a href="{@docRoot}sdk/api_diff/15/changes.html" title="Diff Report">15</a></td>
<td>{@link android.os.Build.VERSION_CODES#ICE_CREAM_SANDWICH_MR1}</td>
<td rowspan="2"><a href="{@docRoot}about/versions/android-4.0-highlights.html">Platform
Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-4.0.html">Android 4.0, 4.0.1, 4.0.2</a></td>
<td><a href="{@docRoot}sdk/api_diff/14/changes.html" title="Diff Report">14</a></td>
<td>{@link android.os.Build.VERSION_CODES#ICE_CREAM_SANDWICH}</td>
</tr>
<tr><td><a href="{@docRoot}about/versions/android-3.2.html">Android 3.2</a></td>
<td><a href="{@docRoot}sdk/api_diff/13/changes.html" title="Diff Report">13</a></td>
<td>{@link android.os.Build.VERSION_CODES#HONEYCOMB_MR2}</td>
<td><!-- <a href="{@docRoot}about/versions/android-3.2-highlights.html">Platform Highlights</a>--></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-3.1.html">Android 3.1.x</a></td>
<td><a href="{@docRoot}sdk/api_diff/12/changes.html" title="Diff Report">12</a></td>
<td>{@link android.os.Build.VERSION_CODES#HONEYCOMB_MR1}</td>
<td><a href="{@docRoot}about/versions/android-3.1-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-3.0.html">Android 3.0.x</td>
<td><a href="{@docRoot}sdk/api_diff/11/changes.html" title="Diff Report">11</a></td>
<td>{@link android.os.Build.VERSION_CODES#HONEYCOMB}</td>
<td><a href="{@docRoot}about/versions/android-3.0-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-2.3.3.html">Android 2.3.4<br>Android 2.3.3</td>
<td><a href="{@docRoot}sdk/api_diff/10/changes.html" title="Diff Report">10</a></td>
<td>{@link android.os.Build.VERSION_CODES#GINGERBREAD_MR1}</td>
<td rowspan="2"><a href="{@docRoot}about/versions/android-2.3-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-2.3.html">Android 2.3.2<br>Android 2.3.1<br>Android 2.3</td>
<td><a href="{@docRoot}sdk/api_diff/9/changes.html" title="Diff Report">9</a></td>
<td>{@link android.os.Build.VERSION_CODES#GINGERBREAD}</td>
</tr>
<tr><td><a href="{@docRoot}about/versions/android-2.2.html">Android 2.2.x</td>
<td ><a href="{@docRoot}sdk/api_diff/8/changes.html" title="Diff Report">8</a></td>
<td>{@link android.os.Build.VERSION_CODES#FROYO}</td>
<td><a href="{@docRoot}about/versions/android-2.2-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-2.1.html">Android 2.1.x</td>
<td><a href="{@docRoot}sdk/api_diff/7/changes.html" title="Diff Report">7</a></td>
<td>{@link android.os.Build.VERSION_CODES#ECLAIR_MR1}</td>
<td rowspan="3" ><a href="{@docRoot}about/versions/android-2.0-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-2.0.1.html">Android 2.0.1</td>
<td><a href="{@docRoot}sdk/api_diff/6/changes.html" title="Diff Report">6</a></td>
<td>{@link android.os.Build.VERSION_CODES#ECLAIR_0_1}</td>
</tr>
<tr><td><a href="{@docRoot}about/versions/android-2.0.html">Android 2.0</td>
<td><a href="{@docRoot}sdk/api_diff/5/changes.html" title="Diff Report">5</a></td>
<td>{@link android.os.Build.VERSION_CODES#ECLAIR}</td>
</tr>
<tr><td><a href="{@docRoot}about/versions/android-1.6.html">Android 1.6</td>
<td><a href="{@docRoot}sdk/api_diff/4/changes.html" title="Diff Report">4</a></td>
<td>{@link android.os.Build.VERSION_CODES#DONUT}</td>
<td><a href="{@docRoot}about/versions/android-1.6-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-1.5.html">Android 1.5</td>
<td><a href="{@docRoot}sdk/api_diff/3/changes.html" title="Diff Report">3</a></td>
<td>{@link android.os.Build.VERSION_CODES#CUPCAKE}</td>
<td><a href="{@docRoot}about/versions/android-1.5-highlights.html">Platform Highlights</a></td></tr>
<tr><td><a href="{@docRoot}about/versions/android-1.1.html">Android 1.1</td>
<td>2</td>
<td>{@link android.os.Build.VERSION_CODES#BASE_1_1}</td><td></td></tr>
<tr><td>Android 1.0</td>
<td>1</td>
<td>{@link android.os.Build.VERSION_CODES#BASE}</td>
<td></td></tr>
</table>
<h2 id="uses">Uses of API Level in Android</h2>
<p>The API Level identifier serves a key role in ensuring the best possible
experience for users and application developers:
<ul>
<li>It lets the Android platform describe the maximum framework API revision
that it supports</li>
<li>It lets applications describe the framework API revision that they
require</li>
<li>It lets the system negotiate the installation of applications on the user's
device, such that version-incompatible applications are not installed.</li>
</ul>
<p>Each Android platform version stores its API Level identifier internally, in
the Android system itself. </p>
<p>Applications can use a manifest element provided by the framework API &mdash;
<code>&lt;uses-sdk&gt;</code> &mdash; to describe the minimum and maximum API
Levels under which they are able to run, as well as the preferred API Level that
they are designed to support. The element offers three key attributes:</p>
<ul>
<li><code>android:minSdkVersion</code> &mdash; Specifies the minimum API Level
on which the application is able to run. The default value is "1".</li>
<li><code>android:targetSdkVersion</code> &mdash; Specifies the API Level
on which the application is designed to run. In some cases, this allows the
application to use manifest elements or behaviors defined in the target
API Level, rather than being restricted to using only those defined
for the minimum API Level.</li>
<li><code>android:maxSdkVersion</code> &mdash; Specifies the maximum API Level
on which the application is able to run. <strong>Important:</strong> Please read the <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
documentation before using this attribute. </li>
</ul>
<p>For example, to specify the minimum system API Level that an application
requires in order to run, the application would include in its manifest a
<code>&lt;uses-sdk&gt;</code> element with a <code>android:minSdkVersion</code>
attribute. The value of <code>android:minSdkVersion</code> would be the integer
corresponding to the API Level of the earliest version of the Android platform
under which the application can run. </p>
<p>When the user attempts to install an application, or when revalidating an
appplication after a system update, the Android system first checks the
<code>&lt;uses-sdk&gt;</code> attributes in the application's manifest and
compares the values against its own internal API Level. The system allows the
installation to begin only if these conditions are met:</p>
<ul>
<li>If a <code>android:minSdkVersion</code> attribute is declared, its value
must be less than or equal to the system's API Level integer. If not declared,
the system assumes that the application requires API Level 1. </li>
<li>If a <code>android:maxSdkVersion</code> attribute is declared, its value
must be equal to or greater than the system's API Level integer.
If not declared, the system assumes that the application
has no maximum API Level. Please read the <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
documentation for more information about how the system handles this attribute.</li>
</ul>
<p>When declared in an application's manifest, a <code>&lt;uses-sdk&gt;</code>
element might look like this: </p>
<pre>&lt;manifest&gt;
&lt;uses-sdk android:minSdkVersion="5" /&gt;
...
&lt;/manifest&gt;</pre>
<p>The principal reason that an application would declare an API Level in
<code>android:minSdkVersion</code> is to tell the Android system that it is
using APIs that were <em>introduced</em> in the API Level specified. If the
application were to be somehow installed on a platform with a lower API Level,
then it would crash at run-time when it tried to access APIs that don't exist.
The system prevents such an outcome by not allowing the application to be
installed if the lowest API Level it requires is higher than that of the
platform version on the target device.</p>
<p>For example, the {@link android.appwidget} package was introduced with API
Level 3. If an application uses that API, it must declare a
<code>android:minSdkVersion</code> attribute with a value of "3". The
application will then be installable on platforms such as Android 1.5 (API Level
3) and Android 1.6 (API Level 4), but not on the Android 1.1 (API Level 2) and
Android 1.0 platforms (API Level 1).</p>
<p>For more information about how to specify an application's API Level
requirements, see the <a
href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><code>&lt;uses-sdk&gt;</code></a>
section of the manifest file documentation.</p>
<h2 id="considerations">Development Considerations</h2>
<p>The sections below provide information related to API level that you should
consider when developing your application.</p>
<h3 id="fc">Application forward compatibility</h3>
<p>Android applications are generally forward-compatible with new versions of
the Android platform.</p>
<p>Because almost all changes to the framework API are additive, an Android
application developed using any given version of the API (as specified by its
API Level) is forward-compatible with later versions of the Android platform and
higher API levels. The application should be able to run on all later versions
of the Android platform, except in isolated cases where the application uses a
part of the API that is later removed for some reason. </p>
<p>Forward compatibility is important because many Android-powered devices
receive over-the-air (OTA) system updates. The user may install your
application and use it successfully, then later receive an OTA update to a new
version of the Android platform. Once the update is installed, your application
will run in a new run-time version of the environment, but one that has the API
and system capabilities that your application depends on. </p>
<p>In some cases, changes <em>below</em> the API, such those in the underlying
system itself, may affect your application when it is run in the new
environment. For that reason it's important for you, as the application
developer, to understand how the application will look and behave in each system
environment. To help you test your application on various versions of the Android
platform, the Android SDK includes multiple platforms that you can download.
Each platform includes a compatible system image that you can run in an AVD, to
test your application. </p>
<h3 id="bc">Application backward compatibility</h3>
<p>Android applications are not necessarily backward compatible with versions of
the Android platform older than the version against which they were compiled.
</p>
<p>Each new version of the Android platform can include new framework APIs, such
as those that give applications access to new platform capabilities or replace
existing API parts. The new APIs are accessible to applications when running on
the new platform and, as mentioned above, also when running on later versions of
the platform, as specified by API Level. Conversely, because earlier versions of
the platform do not include the new APIs, applications that use the new APIs are
unable to run on those platforms.</p>
<p>Although it's unlikely that an Android-powered device would be downgraded to
a previous version of the platform, it's important to realize that there are
likely to be many devices in the field that run earlier versions of the
platform. Even among devices that receive OTA updates, some might lag and
might not receive an update for a significant amount of time. </p>
<h3 id="platform">Selecting a platform version and API Level</h3>
<p>When you are developing your application, you will need to choose
the platform version against which you will compile the application. In
general, you should compile your application against the lowest possible
version of the platform that your application can support.
<p>You can determine the lowest possible platform version by compiling the
application against successively lower build targets. After you determine the
lowest version, you should create an AVD using the corresponding platform
version (and API Level) and fully test your application. Make sure to declare a
<code>android:minSdkVersion</code> attribute in the application's manifest and
set its value to the API Level of the platform version. </p>
<h3 id="apilevel">Declaring a minimum API Level</h3>
<p>If you build an application that uses APIs or system features introduced in
the latest platform version, you should set the
<code>android:minSdkVersion</code> attribute to the API Level of the latest
platform version. This ensures that users will only be able to install your
application if their devices are running a compatible version of the Android
platform. In turn, this ensures that your application can function properly on
their devices. </p>
<p>If your application uses APIs introduced in the latest platform version but
does <em>not</em> declare a <code>android:minSdkVersion</code> attribute, then
it will run properly on devices running the latest version of the platform, but
<em>not</em> on devices running earlier versions of the platform. In the latter
case, the application will crash at runtime when it tries to use APIs that don't
exist on the earlier versions.</p>
<h3 id="testing">Testing against higher API Levels</h3>
<p>After compiling your application, you should make sure to test it on the
platform specified in the application's <code>android:minSdkVersion</code>
attribute. To do so, create an AVD that uses the platform version required by
your application. Additionally, to ensure forward-compatibility, you should run
and test the application on all platforms that use a higher API Level than that
used by your application. </p>
<p>The Android SDK includes multiple platform versions that you can use,
including the latest version, and provides an updater tool that you can use to
download other platform versions as necessary. </p>
<p>To access the updater, use the <code>android</code> command-line tool,
located in the &lt;sdk&gt;/tools directory. You can launch the SDK updater by
executing <code>android sdk</code>. You can
also simply double-click the android.bat (Windows) or android (OS X/Linux) file.
In ADT, you can also access the updater by selecting
<strong>Window</strong>&nbsp;>&nbsp;<strong>Android SDK
Manager</strong>.</p>
<p>To run your application against different platform versions in the emulator,
create an AVD for each platform version that you want to test. For more
information about AVDs, see <a
href="{@docRoot}tools/devices/index.html">Creating and Managing Virtual Devices</a>. If
you are using a physical device for testing, ensure that you know the API Level
of the Android platform it runs. See the table at the top of this document for
a list of platform versions and their API Levels. </p>
<h2 id="provisional">Using a Provisional API Level</h2>
<p>In some cases, an "Early Look" Android SDK platform may be available. To let
you begin developing on the platform although the APIs may not be final, the
platform's API Level integer will not be specified. You must instead use the
platform's <em>provisional API Level</em> in your application manifest, in order
to build applications against the platform. A provisional API Level is not an
integer, but a string matching the codename of the unreleased platform version.
The provisional API Level will be specified in the release notes for the Early
Look SDK release notes and is case-sensitive.</p>
<p>The use of a provisional API Level is designed to protect developers and
device users from inadvertently publishing or installing applications based on
the Early Look framework API, which may not run properly on actual devices
running the final system image.</p>
<p>The provisional API Level will only be valid while using the Early Look SDK
and can only be used to run applications in the emulator. An application using
the provisional API Level can never be installed on an Android device. At the
final release of the platform, you must replace any instances of the provisional
API Level in your application manifest with the final platform's actual API
Level integer.</p>
<h2 id="filtering">Filtering the Reference Documentation by API Level</h2>
<p>Reference documentation pages on the Android Developers site offer a "Filter
by API Level" control in the top-right area of each page. You can use the
control to show documentation only for parts of the API that are actually
accessible to your application, based on the API Level that it specifies in
the <code>android:minSdkVersion</code> attribute of its manifest file. </p>
<p>To use filtering, select the checkbox to enable filtering, just below the
page search box. Then set the "Filter by API Level" control to the same API
Level as specified by your application. Notice that APIs introduced in a later
API Level are then grayed out and their content is masked, since they would not
be accessible to your application. </p>
<p>Filtering by API Level in the documentation does not provide a view
of what is new or introduced in each API Level &mdash; it simply provides a way
to view the entire API associated with a given API Level, while excluding API
elements introduced in later API Levels.</p>
<p>If you decide that you don't want to filter the API documentation, just
disable the feature using the checkbox. By default, API Level filtering is
disabled, so that you can view the full framework API, regardless of API Level.
</p>
<p>Also note that the reference documentation for individual API elements
specifies the API Level at which each element was introduced. The API Level
for packages and classes is specified as "Since &lt;api level&gt;" at the
top-right corner of the content area on each documentation page. The API Level
for class members is specified in their detailed description headers,
at the right margin. </p>

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page.title=App Framework
@jd:body
<p>Android is a software stack for mobile devices that includes an operating
system, middleware and key applications. The <a
href="http://developer.android.com/sdk/index.html">Android SDK</a>
provides the tools and APIs necessary to begin developing applications on the
Android platform using the Java programming language.</p>
<h2>Features</h2>
<ul>
<li><strong>Application framework</strong> enabling reuse and replacement
of components</li>
<li><strong>Dalvik virtual machine</strong> optimized for mobile
devices</li>
<li><strong>Integrated browser</strong> based on the open source <a
href="http://webkit.org/">WebKit</a> engine </li>
<li><strong>Optimized graphics</strong> powered by a custom 2D graphics library; 3D
graphics based on the OpenGL ES 1.0 specification (hardware acceleration
optional)</li>
<li><strong>SQLite</strong> for structured data storage</li>
<li><strong>Media support</strong> for common audio, video, and still
image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG,
GIF)</li>
<li><strong>GSM Telephony</strong> (hardware dependent)</li>
<li><strong>Bluetooth, EDGE, 3G, and WiFi</strong> (hardware dependent)</li>
<li><strong>Camera, GPS, compass, and accelerometer</strong> (hardware dependent)</li>
<li><strong>Rich development environment</strong> including a device
emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE</li>
</ul>
<a name="os_architecture" id="os_architecture"></a>
<h2>Android Architecture</h2>
<p>The following diagram shows the major components of the Android operating
system. Each section is described in more detail below.</p>
<p><img src="{@docRoot}images/system-architecture.jpg" alt="Android System Architecture" width="713" height="512"></p>
<a name="applications" id="applications"></a>
<h2>Applications</h2>
<p>Android will ship with a set of core applications including an email
client, SMS program, calendar, maps, browser, contacts, and
others. All applications are written using the Java programming language.</p>
<a name="application_framework" id="application_framework"></a>
<h2>Application Framework</h2>
<p>By providing an open development platform, Android
offers developers the ability to build extremely rich and innovative
applications. Developers are free to take advantage of the
device hardware, access location information, run background services, set alarms,
add notifications to the status bar, and much, much more. </p>
<p>Developers have full access to the same framework APIs used by the core
applications. The application architecture is designed to simplify the reuse
of components; any application can publish its capabilities and any other
application may then make use of those capabilities (subject to security
constraints enforced by the framework). This same mechanism allows components
to be replaced by the user.</p>
<p>Underlying all applications is a set of services and systems, including:
<ul>
<li>A rich and extensible set of <a
href="{@docRoot}resources/tutorials/views/index.html">Views</a> that can be used to
build an application, including lists, grids, text boxes, buttons, and even
an embeddable web browser</li>
<li><a href="{@docRoot}guide/topics/providers/content-providers.html">Content
Providers</a> that enable applications to access data from other
applications (such as Contacts), or to share their own data</li> <li>A <a
href="{@docRoot}guide/topics/resources/resources-i18n.html">Resource
Manager</a>, providing access to non-code resources such as localized
strings, graphics, and layout files</li>
<li>A {@link android.app.NotificationManager Notification Manager} that enables
all applications to display custom alerts in the status bar</li>
<li>An {@link android.app.Activity Activity Manager} that manages the
lifecycle of applications and provides a common navigation backstack</li>
</ul>
<p>For more details and a walkthrough of an application, see the <a
href="{@docRoot}training/notepad/index.html">Notepad Tutorial</a>.</p>
<a name="libraries" id="libraries"></a>
<h2>Libraries</h2>
<p>Android includes a set of C/C++ libraries used by various components of the
Android system. These capabilities are exposed to developers through the
Android application framework. Some of the core libraries are listed below:</p>
<ul>
<li><strong>System C library</strong> - a BSD-derived implementation of
the standard C system library (libc), tuned for embedded Linux-based
devices</li>
<li><strong>Media Libraries</strong> - based on PacketVideo's OpenCORE;
the libraries support playback and recording of many popular audio and video
formats, as well as static image files, including MPEG4, H.264, MP3, AAC,
AMR, JPG, and PNG</li>
<li><strong>Surface Manager</strong> - manages access to the display
subsystem and seamlessly composites 2D and 3D graphic layers from multiple
applications</li>
<li><strong>LibWebCore</strong> - a modern web browser engine which
powers both the Android browser and an embeddable web view</li>
<li><strong>SGL</strong> - the underlying 2D graphics
engine</li>
<li><strong>3D libraries</strong> - an implementation based on
OpenGL ES 1.0 APIs; the libraries use either hardware 3D acceleration
(where available) or the included, highly optimized 3D software
rasterizer</li>
<li><strong>FreeType</strong> - bitmap and vector font rendering</li>
<li><strong>SQLite</strong> - a powerful and lightweight relational
database engine available to all applications</li>
</ul>
<a name="runtime" id="runtime"></a>
<h2>Android Runtime</h2>
<p>Android includes a set of core libraries that provides most of
the functionality available in the core libraries of the Java programming
language.</p>
<p>Every Android application runs in its own process, with its own instance of
the Dalvik virtual machine. Dalvik has been written so that a device can run
multiple VMs efficiently. The Dalvik VM executes files in the Dalvik
Executable (.dex) format which is optimized for minimal memory
footprint. The VM is register-based, and runs classes
compiled by a Java language compiler that have been transformed into the .dex
format by the included &quot;dx&quot; tool.</p>
<p>The Dalvik VM relies on the Linux kernel for underlying functionality such
as threading and low-level memory management.</p>
<a name="kernel" id="kernel"></a>
<h2>Linux Kernel</h2>
<p>Android relies on Linux version 2.6 for core system services such as
security, memory management, process management, network stack, and driver
model. The kernel also acts as an abstraction layer between the hardware and
the rest of the software stack.</p>

View File

@@ -1,6 +1,5 @@
page.title=&lt;uses-feature&gt;
parent.title=The AndroidManifest.xml File
parent.link=manifest-intro.html
page.tags="filtering","features","google play filters","permissions"
@jd:body
<div id="qv-wrapper">

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@@ -1,6 +1,5 @@
page.title=&lt;uses-sdk&gt;
parent.title=The AndroidManifest.xml File
parent.link=manifest-intro.html
page.tags="api levels","sdk version","minsdkversion","targetsdkversion","maxsdkversion"
@jd:body