跳转至

WebView

WebView常用方法

  • public void loadUrl \(String url\)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
//打开本包内asset目录下的test.html文件
loadUrl("file:///android_asset/test.html");
//打开本地sd卡内的kris.html文件
loadUrl("content://com.android.htmlfileprovider/sdcard/malinkang.html");
//打开指定URL的html文件
loadUrl("http://malinkang.com/");
//使用loadUrl调用javascript方法
loadUrl("javascript:test()");
//调用javascript方法传入参数
loadUrl("javascript:test(\"hello\")");

有时候html可能需要从资源文件中加载图片

1
<img src="file:///android_res/drawable/a.png">
  • loadData\(String data, String mimeType, String encoding\)
  • loadDataWithBaseURL\(String baseUrl, String data, String mimeType, String encoding, String historyUrl\)
1
2
3
4
//加载字符串 4.0+没有问题，2.3下乱码
loadData(htmlStr, "text/html;charset=utf-8",null);
//4.0+和2.3都没有问题
loadDataWithBaseURL(null, htmlStr,"text/html", "utf-8", null);
  • public String getTitle()：获取当前页面的title

WebChromeClient

WebChromeClient是辅助WebView处理Javascript的对话框,网站图标,网站title等。常用方法如下：

  • public void onProgressChanged\(WebView view, int newProgress\) {}：告诉应用网页加载进度

WebView源码分析

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
//WebView的所有操作都是通过调用Provider相应的方法
private WebViewProvider mProvider;
//创建WebViewProvider
private void ensureProviderCreated() {
    checkThread();
    if (mProvider == null) {
        // As this can get called during the base class constructor chain, pass the minimum
        // number of dependencies here; the rest are deferred to init().
        mProvider = getFactory().createWebView(this, new PrivateAccess());
    }
}
//获取WebViewFactoryProvider
@UnsupportedAppUsage
private static WebViewFactoryProvider getFactory() {
    //内部通过反射获取WebViewFactoryProvider，不同的版本可能
   //创建不同的WebViewFactoryProvider，
    return WebViewFactory.getProvider();
}

WebViewFactory

1
2
3
//类的路径
private static final String CHROMIUM_WEBVIEW_FACTORY =
           "com.android.webview.chromium.WebViewChromiumFactoryProviderForQ";

5.0版本的WebView创建的WebViewFactoryProvider对象为WebViewChromiumFactoryProvider。

WebViewChromiumFactoryProvider

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
@Override
public WebViewProvider createWebView(WebView webView, WebView.PrivateAccess privateAccess) {
    //创建WebView内核
    WebViewChromium wvc = new WebViewChromium(this, webView, privateAccess);
    synchronized (mLock) {
        if (mWebViewsToStart != null) {
            mWebViewsToStart.add(new WeakReference<WebViewChromium>(wvc));
        }
    }
    return wvc;
}

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
@Override
public void addJavascriptInterface(final Object obj, final String interfaceName) {
    if (checkNeedsPost()) {
        //WebViewChromiumRunQueue
        mRunQueue.addTask(new Runnable() {
            @Override
            public void run() {
                addJavascriptInterface(obj, interfaceName);
            }
        });
        return;
    }
    Class<? extends Annotation> requiredAnnotation = null;
    if (mAppTargetSdkVersion >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
       requiredAnnotation = JavascriptInterface.class;
    }
   //AwContents
    mAwContents.addPossiblyUnsafeJavascriptInterface(obj, interfaceName, requiredAnnotation);
}

https://github.com/pwnall/chromeview/blob/master/src/org/chromium/android_webview/AwContents.java

1
2
3
4
5
6
7
    /**
     * @see ContentViewCore#addPossiblyUnsafeJavascriptInterface(Object, String, Class)
     */
    public void addPossiblyUnsafeJavascriptInterface(Object object, String name,
            Class<? extends Annotation> requiredAnnotation) {
        mContentViewCore.addPossiblyUnsafeJavascriptInterface(object, name, requiredAnnotation);
    }

https://chromium.googlesource.com/chromium/src/+/9d343ad2ea6ec395c377a4efa266057155bfa9c1/content/public/android/java/src/org/chromium/content/browser/ContentViewCore.java

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
   */
public void addJavascriptInterface(Object object, String name) {
    addPossiblyUnsafeJavascriptInterface(object, name, JavascriptInterface.class);
}
public void addPossiblyUnsafeJavascriptInterface(Object object, String name,
        Class<? extends Annotation> requiredAnnotation) {
    if (mNativeContentViewCore != 0 && object != null) {
        mJavaScriptInterfaces.put(name, new Pair<Object, Class>(object, requiredAnnotation));
        //本地方法
        nativeAddJavascriptInterface(mNativeContentViewCore, object, name, requiredAnnotation);
    }
}

更多阅读