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0. 寫在前面

 style="?android:attr/progressBarStyleHorizontal" 
在WebView的開發過程中當你需要使用到一些高級功能可以通過設置WebChromeClient從而來輔助WebView處理 javaScript 的對話框、網站圖標、網站title、加載進度等。
WebChromeClient常用的API方法
1.通知應用程序當前網頁加載的進度
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@Overridepublic void onProgressChanged(WebView view, int newProgress)
2.獲取網頁title標題
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@Overridepublic void onReceivedTitle(WebView view, String title)
獲取標題的時間主要取決于網頁前段設置標題的位置，一般設置在頁面加載前面，可以較早調用到這個函數
3.網頁中有H5播放Flash video的時候按下全屏按鈕將會調用到這個方法，一般用作設置網頁播放全屏操作
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@Overridepublic void onShowCustomView(View view, CustomViewCallback callback)
對應的取消全屏方法
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@Overridepublic void onHideCustomView()
WebView下載監聽
通過設置webview下載監聽進而監聽網頁下載
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mWebView.setDownloadListener(new DownloadListener() {    @Override    public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {    }});
一般可在downloadStart 處進行下載處理
WebChromeClient高級功能實現
1.讓你的webview支持File Input 標簽
在Android 5.0 API 21后 借助新的 onShowFileChooser() 方法,您現在不但可以在 WebView 中使用輸入表單字段,而且可以啟動文件選擇器從 Android 設備中選擇圖片和文件
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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;}
在選擇完圖片后回調onActivityResult 獲取圖片
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@Overridepublic 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.支持全屏視頻播放
設置webview視頻未播放時默認顯示占位圖
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@Overridepublic Bitmap getDefaultVideoPoster() {    if(getActivity() == null) {        return null;    }    return BitmapFactory.decodeResource(getActivity().getapplicationContext().getResources(),            R.drawable.video_poster);}
視頻播放全屏時調用
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@Overridepublic 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);}
視頻取消全屏時候調用
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@Overridepublic 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;}