2 parent.title=Hello, Views
6 <p>{@link android.webkit.WebView} allows you to create your own window for viewing web pages (or even
7 develop a complete browser). In this tutorial, you'll create a simple {@link android.app.Activity}
8 that can view and navigate web pages.</p>
11 <li>Create a new project named <em>HelloWebView</em>.</li>
12 <li>Open the <code>res/layout/main.xml</code> file and insert the following:
14 <?xml version="1.0" encoding="utf-8"?>
15 <WebView xmlns:android="http://schemas.android.com/apk/res/android"
16 android:id="@+id/webview"
17 android:layout_width="fill_parent"
18 android:layout_height="fill_parent"
23 <li>Now open the <code>HelloWebView.java</code> file.
24 At the top of the class, declare a {@link android.webkit.WebView} object:
25 <pre>WebView mWebView;</pre>
26 <p>Then use the following code for the {@link android.app.Activity#onCreate(Bundle) onCreate()}
29 public void onCreate(Bundle savedInstanceState) {
30 super.onCreate(savedInstanceState);
31 setContentView(R.layout.main);
33 mWebView = (WebView) findViewById(R.id.webview);
34 mWebView.getSettings().setJavaScriptEnabled(true);
35 mWebView.loadUrl("http://www.google.com");
38 <p>This initializes the member {@link android.webkit.WebView} with the one from the
39 {@link android.app.Activity} layout; requests a {@link android.webkit.WebSettings} object with
40 {@link android.webkit.WebView#getSettings()}; and enables JavaScript for the {@link
41 android.webkit.WebView} with {@link android.webkit.WebSettings#setJavaScriptEnabled(boolean)}.
42 Finally, an initial web page is loaded with {@link
43 android.webkit.WebView#loadUrl(String)}.</p>
46 <li>Because this application needs access to the Internet, you need to add the appropriate
47 permissions to the Android manifest file. Open the <code>AndroidManifest.xml</code> file
48 and add the following as a child of the <code><manifest></code> element:
50 <pre><uses-permission android:name="android.permission.INTERNET" /></pre></li>
52 <li>While you're in the manifest, give some more space for web pages by removing the title
53 bar, with the "NoTitleBar" theme:
55 <activity android:name=".HelloGoogleMaps" android:label="@string/app_name"
56 <strong>android:theme="@android:style/Theme.NoTitleBar"</strong>>
60 <li>Now run the application.
61 <p>You now have a simplest web page viewer.
62 It's not quite a browser yet because as soon as you click a link, the default Android Browser
63 handles the Intent to view a web page, because this {@link android.app.Activity} isn't
64 technically enabled to do so. Instead of adding an intent filter to view web pages, you can
65 override the {@link android.webkit.WebViewClient} class and enable this {@link
66 android.app.Activity} to handle its own URL requests.</p>
69 <li>In the <code>HelloAndroid</code> Activity, add this nested class:
71 private class HelloWebViewClient extends WebViewClient {
73 public boolean shouldOverrideUrlLoading(WebView view, String url) {
80 <li>Then towards the end of the {@link android.app.Activity#onCreate(Bundle)} method, set an
81 instance of the <code>HelloWebViewClient</code> as the {@link android.webkit.WebViewClient}:
82 <pre>mWebView.setWebViewClient(new HelloWebViewClient());</pre>
84 <p>This line can go anywhere following the initialization of the {@link
85 android.webkit.WebView} object.</p>
86 <p>This creates a {@link android.webkit.WebViewClient} that will load any URL selected from this
87 {@link android.webkit.WebView} into the same {@link android.webkit.WebView}. The
88 {@link android.webkit.WebViewClient#shouldOverrideUrlLoading(WebView,String)} method is passed
89 the current {@link android.webkit.WebView} and the URL requested, so all it needs to do is load
90 the URL in the given view. Returning <code>true</code> says that the method has handled the URL
91 and the event should not propagate (in which case, an Intent would be created that's handled by
92 the Browser application).</p>
93 <p>If you run the application again, new pages will now load in this Activity.
94 However, you can't navigate back to previous pages. To do this, you need to handle the BACK
95 button on the device, so that it will return to the previous page, rather than exit the
99 <li>To handle the BACK button key press, add the following method inside the
100 <code>HelloWebView</code> Activity:
103 public boolean onKeyDown(int keyCode, KeyEvent event) {
104 if ((keyCode == KeyEvent.KEYCODE_BACK) && mWebView.canGoBack()) {
108 return super.onKeyDown(keyCode, event);
111 <p>This {@link android.app.Activity#onKeyDown(int,KeyEvent)} callback method will be called
112 anytime a button is pressed while in the Activity. The condition inside uses the {@link
113 android.view.KeyEvent} to check whether the key pressed is the BACK button and whether the
114 {@link android.webkit.WebView} is actually capable of navigating back (if it has a history). If
115 both are true, then the {@link android.webkit.WebView#goBack()} method is called,
116 which will navigate back one step in the {@link android.webkit.WebView}
117 history.Returning <code>true</code> indicates that the event has been handled. If this condition
118 is not met, then the event is sent back to the system.</p>
120 <li>Run the application again. You'll now be able to follow links and navigate back through the
123 <p>When you open the application, it should look like this:</p>
124 <img src="images/hello-webview.png" width="150px" />
128 <li>{@link android.webkit.WebView}</li>
129 <li>{@link android.webkit.WebViewClient}</li>
130 <li>{@link android.view.KeyEvent}</li>