See Also: WebView Members
A View that displays web pages. This class is the basis upon which you can roll your own web browser or simply display some online content within your Activity. It uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, perform text searches and more.
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 Android Manifest file:
xml Example
<uses-permission android:name="android.permission.INTERNET" />
This must be a child of the element.
For more information, read Building Web Apps in WebView.
By default, a WebView provides no browser-like widgets, does not 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 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:
java Example
Uri uri = Uri.parse("http://www.example.com");
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
java Example
WebView webview = new WebView(this); setContentView(webview);
java Example
// 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/");
// OR, you can also load from an HTML string:
String summary = "<html><body>You scored <b>192</b> points.</body></html>";
webview.loadData(summary, "text/html", null);
// ... although note that there are restrictions on what this HTML can do.
// See the JavaDocs for loadData() and loadDataWithBaseURL() for more info.
java Example
// Let's display the progress in the activity title bar, like the
// browser app does.
getWindow().requestFeature(Window.FEATURE_PROGRESS);
webview.getSettings().setJavaScriptEnabled(true);
final Activity activity = this;
webview.setWebChromeClient(new WebChromeClient() {
public void onProgressChanged(WebView view, int progress) {
// Activities and WebViews measure progress with different scales.
// The progress meter will automatically disappear when we reach 100%
activity.setProgress(progress * 1000);
}
});
webview.setWebViewClient(new WebViewClient() {
public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
Toast.makeText(activity, "Oh no! " + description, Toast.LENGTH_SHORT).show();
}
});
webview.loadUrl("http://developer.android.com/");
xml Example
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio:1.5)" href="hdpi.css" />
See Android.Content.Intent for more information.
To provide a WebView in your own Activity, include a <WebView> in your layout, or set the entire Activity window as a WebView during Android.App.Activity.OnCreate(Android.OS.Bundle):
Then load the desired web page:
A WebView has several customization points where you can add your own behavior. These are:
Here's a more complicated example, showing error handling, settings, and progress notification:
To enable the built-in zoom, set WebView.Settings.WebSettings.BuiltInZoomControls (introduced in API level NoType:android/os/Build$VERSION_CODES;Href=../../../reference/android/os/Build.VERSION_CODES.html#CUPCAKE).
NOTE: Using zoom if either the height or width is set to NoType:android/view/ViewGroup$LayoutParams;Href=../../../reference/android/view/ViewGroup.LayoutParams.html#WRAP_CONTENT may lead to undefined behavior and should be avoided.
For obvious security reasons, your application has its own cache, cookie store etc.—it does not share the Browser application's data.
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 Android.Webkit.WebChromeClient to provide your own behaviour for opening multiple windows, and render them in whatever manner you want.
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 changes, and then just leave the WebView alone. It'll automatically 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 NoType:android/os/Build$VERSION_CODES;Href=../../../reference/android/os/Build.VERSION_CODES.html#ECLAIR, 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:
The hdpi.css stylesheet is only used for devices with a screen pixel ration of 1.5, which is the high density pixel ratio.
In order to support inline HTML5 video in your application, you need to have hardware acceleration turned on, and set a Android.Webkit.WebChromeClient. For full screen support, implementations of WebChromeClient.OnShowCustomView(Android.Views.View, .ICustomViewCallback) and WebChromeClient.OnHideCustomView are required, WebChromeClient.VideoLoadingProgressView is optional.