webview 不支持文件上传 <input type="file" />

    // 1.设置WebChromeClient，重写文件上传回调
        mWebView.setWebChromeClient(new WebChromeClient() {
            
            // For Android < 3.0
            public void openFileChooser(ValueCallback<Uri> valueCallback) {
                mUploadMessage = valueCallback;
                openImageChooserActivity();
            }

            // For Android  >= 3.0
            public void openFileChooser(ValueCallback valueCallback, String acceptType) {
                mUploadMessage = valueCallback;
                openImageChooserActivity();
            }

            //For Android  >= 4.1
            public void openFileChooser(ValueCallback<Uri> valueCallback, String acceptType, String capture) {
                mUploadMessage = valueCallback;
                openImageChooserActivity();
            }

            // For Android >= 5.0
            @Override
            public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
                mUploadCallbackAboveL = filePathCallback;
                openImageChooserActivity();
                return true;
            }
        });
    
    // 2.回调方法触发本地选择文件    
        private void openImageChooserActivity() {
            Intent i = new Intent(Intent.ACTION_GET_CONTENT);
            i.addCategory(Intent.CATEGORY_OPENABLE);
            i.setType("image/*");
            startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILECHOOSER_RESULTCODE);
    }
    
    // 3.选择图片后处理
        @Override
        protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            if (requestCode == FILE_CHOOSER_RESULT_CODE) {
                if (null == uploadMessage && null == uploadMessageAboveL) return;
                Uri result = data == null || resultCode != RESULT_OK ? null : data.getData();
                if (uploadMessageAboveL != null) {
                    onActivityResultAboveL(requestCode, resultCode, data);
                } else if (uploadMessage != null) {
                    uploadMessage.onReceiveValue(result);
                    uploadMessage = null;
                }
            }
        }
        
    // 4. 选择内容回调到Html页面
        @TargetApi(Build.VERSION_CODES.LOLLIPOP)
        private void onActivityResultAboveL(int requestCode, int resultCode, Intent intent) {
            if (requestCode != FILE_CHOOSER_RESULT_CODE || uploadMessageAboveL == null)
                return;
            Uri[] results = null;
            if (resultCode == Activity.RESULT_OK) {
                if (intent != null) {
                    String dataString = intent.getDataString();
                    ClipData clipData = intent.getClipData();
                    if (clipData != null) {
                        results = new Uri[clipData.getItemCount()];
                        for (int i = 0; i < clipData.getItemCount(); i++) {
                            ClipData.Item item = clipData.getItemAt(i);
                            results[i] = item.getUri();
                        }
                    }
                    if (dataString != null)
                        results = new Uri[]{Uri.parse(dataString)};
                }
            }
            uploadMessageAboveL.onReceiveValue(results);
            uploadMessageAboveL = null;
        }
    }