Note that, in order for your Activity to access the Internet and load web pages - * in a WebView, you must add the INTERNET permissions to your + * in a WebView, you must add the {@code INTERNET} permissions to your * Android Manifest file:
*<uses-permission android:name="android.permission.INTERNET" />* - *
This must be a child of the <manifest> element.
This must be a child of the {@code <manifest>} + * element.
* *By default, a WebView provides no browser-like widgets, does not - * enable JavaScript and errors will be ignored. If your goal is only + * enable JavaScript and web page errors are ignored. If your goal is only * to display some HTML as a part of your UI, this is probably fine; * the user won't need to interact with the web page beyond reading * it, and the web page won't need to interact with the user. If you - * actually want a fully blown web browser, then you probably want to - * invoke the Browser application with your URL rather than show it - * with a WebView. See {@link android.content.Intent} for more information.
+ * actually want a full-blown web browser, then you probably want to + * invoke the Browser application with a URL Intent rather than show it + * with a WebView. For example: + *
+ * Uri uri = Uri.parse("http://www.example.com");
+ * Intent intent = new Intent(Intent.ACTION_VIEW, uri);
+ * startActivity(intent);
+ *
+ * See {@link android.content.Intent} for more information.
* + *To provide a WebView in your own Activity, include a {@code <WebView>} in your layout, + * or set the entire Activity window as a WebView during {@link + * android.app.Activity#onCreate(Bundle) onCreate()}:
** WebView webview = new WebView(this); * setContentView(webview); + ** + *
Then load the desired web page:
* // Simplest usage: note that an exception will NOT be thrown * // if there is an error loading this page (see below). * webview.loadUrl("http://slashdot.org/"); * - * // Of course you can also load from any string: + * // OR, you can also load from an HTML string: * String summary = "<html><body>You scored <b>192 points.</body></html>"; * webview.loadData(summary, "text/html", "utf-8"); * // ... although note that there are restrictions on what this HTML can do. - * // See the JavaDocs for loadData and loadDataWithBaseUrl for more info. + * // See the JavaDocs for {@link #loadData(String,String,String) loadData()} and {@link + * #loadDataWithBaseURL(String,String,String,String,String) loadDataWithBaseURL()} for more info. * * *A WebView has several customization points where you can add your @@ -148,15 +162,20 @@ import junit.framework.Assert; *
For obvious security reasons, your application has its own - * cache, cookie store etc - it does not share the Browser - * applications data. Cookies are managed on a separate thread, so + * cache, cookie store etc.—it does not share the Browser + * application's data. Cookies are managed on a separate thread, so * operations like index building don't block the UI * thread. Follow the instructions in {@link android.webkit.CookieSyncManager} * if you want to use cookies in your application. @@ -201,15 +220,79 @@ import junit.framework.Assert; *
By default, requests by the HTML to open new windows are * ignored. This is true whether they be opened by JavaScript or by * the target attribute on a link. You can customize your - * WebChromeClient to provide your own behaviour for opening multiple windows, + * {@link WebChromeClient} to provide your own behaviour for opening multiple windows, * and render them in whatever manner you want.
* - *Standard behavior for an Activity is to be destroyed and - * recreated when the devices orientation is changed. This will cause + *
The standard behavior for an Activity is to be destroyed and + * recreated when the device orientation or any other configuration changes. This will cause * the WebView to reload the current page. If you don't want that, you - * can set your Activity to handle the orientation and keyboardHidden + * can set your Activity to handle the {@code orientation} and {@code keyboardHidden} * changes, and then just leave the WebView alone. It'll automatically - * re-orient itself as appropriate.
+ * re-orient itself as appropriate. Read Handling Runtime Changes for + * more information about how to handle configuration changes during runtime. + * + * + *The screen density of a device is based on the screen resolution. A screen with low density + * has fewer available pixels per inch, where a screen with high density + * has more — sometimes significantly more — pixels per inch. The density of a + * screen is important because, other things being equal, a UI element (such as a button) whose + * height and width are defined in terms of screen pixels will appear larger on the lower density + * screen and smaller on the higher density screen. + * For simplicity, Android collapses all actual screen densities into three generalized densities: + * high, medium, and low.
+ *By default, WebView scales a web page so that it is drawn at a size that matches the default + * appearance on a medium density screen. So, it applies 1.5x scaling on a high density screen + * (because its pixels are smaller) and 0.75x scaling on a low density screen (because its pixels + * are bigger). + * Starting with API Level 5 (Android 2.0), WebView supports DOM, CSS, and meta tag features to help + * you (as a web developer) target screens with different screen densities.
+ *Here's a summary of the features you can use to handle different screen densities:
+ *+ * <link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio:1.5)" href="hdpi.css" />+ *
The {@code hdpi.css} stylesheet is only used for devices with a screen pixel ration of 1.5, + * which is the high density pixel ratio.
+ *Here's an example meta tag to specify the target density:
+ *<meta name="viewport" content="target-densitydpi=device-dpi" />
If you want to modify your web page for different densities, by using the {@code + * -webkit-device-pixel-ratio} CSS media query and/or the {@code + * window.devicePixelRatio} DOM property, then you should set the {@code target-densitydpi} meta + * property to {@code device-dpi}. This stops Android from performing scaling in your web page and + * allows you to make the necessary adjustments for each density via CSS and JavaScript.
+ * + * */ @Widget public class WebView extends AbsoluteLayout