在WebView的开发过程中当你需要使用到一些高级功能可以通过设置WebChromeClient从而来辅助WebView处理 JavaScript 的对话框、网站图标、网站title、加载进度等
WebChromeClient常用的API方法
1.通知应用程序当前网页加载的进度
@Override
public void onProgressChanged(WebView view, int newProgress)
2.获取网页title标题
@Override
public void onReceivedTitle(WebView view, String title)
获取标题的时间主要取决于网页前段设置标题的位置，一般设置在页面加载前面，可以较早调用到这个函数
3.网页中有H5播放flash video的时候按下全屏按钮将会调用到这个方法，一般用作设置网页播放全屏操作
@Override
public void onShowCustomView(View view, CustomViewCallback callback)
对应的取消全屏方法
@Override
public void onHideCustomView()
WebView下载监听
通过设置webview下载监听进而监听网页下载
mWebView.setDownloadListener(new DownloadListener() {
@Override
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
}
});
一般可在downloadStart 处进行下载处理
WebChromeClient高级功能实现
1.让你的webview支持File Input 标签
在Android 5.0 API 21后 借助新的 onShowFileChooser() 方法,您现在不但可以在 WebView 中使用输入表单字段,而且可以启动文件选择器从 Android 设备中选择图片和文件
public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback,
WebChromeClient.FileChooserParams fileChooserParams) {
if (mFilePathCallback != null) {
mFilePathCallback.onReceiveValue(null);
}
mFilePathCallback = filePathCallback;
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
// Create the File where the photo should go
File photoFile = null;
try {
photoFile = createImageFile();
takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
} catch (IOException ex) {
// Error occurred while creating the File
Log.e(TAG, "Unable to create Image File", ex);
}
// Continue only if the File was successfully created
if (photoFile != null) {
mCameraPhotoPath = "file:" + photoFile.getAbsolutePath();
takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT,
Uri.fromFile(photoFile));
} else {
takePictureIntent = null;
}
}
Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
contentSelectionIntent.setType("image/*");
Intent[] intentArray;
if (takePictureIntent != null) {
intentArray = new Intent[]{takePictureIntent};
} else {
intentArray = new Intent[0];
}
Intent chooserIntent = new Intent(Intent.ACTION_CHOOSER);
chooserIntent.putExtra(Intent.EXTRA_INTENT, contentSelectionIntent);
chooserIntent.putExtra(Intent.EXTRA_TITLE, "Image Chooser");
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, intentArray);
startActivityForResult(chooserIntent, INPUT_FILE_REQUEST_CODE);
return true;
}
在选择完图片后回调onActivityResult 获取图片
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode != INPUT_FILE_REQUEST_CODE || mFilePathCallback == null) {
super.onActivityResult(requestCode, resultCode, data);
return;
}
Uri[] results = null;
// Check that the response is a good one
if (resultCode == Activity.RESULT_OK) {
if (data == null) {
// If there is not data, then we may have taken a photo
if (mCameraPhotoPath != null) {
results = new Uri[]{Uri.parse(mCameraPhotoPath)};
}
} else {
String dataString = data.getDataString();
if (dataString != null) {
results = new Uri[]{Uri.parse(dataString)};
}
}
}
mFilePathCallback.onReceiveValue(results);
mFilePathCallback = null;
return;
}
2.支持全屏视频播放
设置webview视频未播放时默认显示占位图
@Override
public Bitmap getDefaultVideoPoster() {
if(getActivity() == null) {
return null;
}
return BitmapFactory.decodeResource(getActivity().getApplicationContext().getResources(),
R.drawable.video_poster);
}
视频播放全屏时调用
@Override
public void onShowCustomView(View view,
WebChromeClient.CustomViewCallback callback) {
// if a view already exists then immediately terminate the new one
if (mCustomView != null) {
onHideCustomView();
return;
}
// 1. Stash the current state
mCustomView = view;
mOriginalSystemUiVisibility = getActivity().getWindow().getDecorView().getSystemUiVisibility();
mOriginalOrientation = getActivity().getRequestedOrientation();
// 2. Stash the custom view callback
mCustomViewCallback = callback;
// 3. Add the custom view to the view hierarchy
FrameLayout decor = (FrameLayout) getActivity().getWindow().getDecorView();
decor.addView(mCustomView, new FrameLayout.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
// 4. Change the state of the window
getActivity().getWindow().getDecorView().setSystemUiVisibility(
View.SYSTEM_UI_FLAG_LAYOUT_STABLE |
View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION |
View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN |
View.SYSTEM_UI_FLAG_HIDE_NAVIGATION |
View.SYSTEM_UI_FLAG_FULLSCREEN |
View.SYSTEM_UI_FLAG_IMMERSIVE);
getActivity().setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
}
视频取消全屏时候调用
@Override
public void onHideCustomView() {
// 1. Remove the custom view
FrameLayout decor = (FrameLayout) getActivity().getWindow().getDecorView();
decor.removeView(mCustomView);
mCustomView = null;
// 2. Restore the state to it's original form
getActivity().getWindow().getDecorView()
.setSystemUiVisibility(mOriginalSystemUiVisibility);
getActivity().setRequestedOrientation(mOriginalOrientation);
// 3. Call the custom view callback
mCustomViewCallback.onCustomViewHidden();
mCustomViewCallback = null;
}
具体实例可以参照 GoogleChrome高级使用实例
[https://github.com/GoogleChrome/chromium-webview-samples]
下篇将讲解WebView优化以及在开发过程中常遇到的问题
