1.添加以下代码到AndroidManifest.xml文件中的Webview activity中。

android:hardwareAccelerated="false"
android:allowFileAccess="true"
android:allowContentAccess="true"

2.在Webview的Client中覆写onShowFileChooser方法，示例如下：

@Override
public boolean onShowFileChooser(WebView webView, ValueCallback filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
    if (mFilePathCallback != null) {
        mFilePathCallback.onReceiveValue(null);
    }
    mFilePathCallback = filePathCallback;
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (takePictureIntent.resolveActivity(webView.getContext().getPackageManager()) != null) {
        File photoFile = null;
        try {
            photoFile = createImageFile();
            takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
        } catch (IOException ex) {
            Log.e(TAG, "Unable to create Image File", ex);
        }
        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("*/*");
    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, "FileChooser");
    chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, intentArray);
    startActivityForResult(chooserIntent, mRequestCodeFilePicker);
    return true;
}

3.在Webview的 activity 中添加以下 onActivityResult 方法代码。

@Override
public void onActivityResult(int requestCode, int resultCode, Intent intent) {
    if (requestCode == mRequestCodeFilePicker) {
        if (mFilePathCallback == null) {
            return;
        }
        if (