需求：

Android中webview載入網頁，網頁中有一個按鈕，點選之後，調啟Android系統的相機和相簿。

問題：

前端中的<input type="file" accept="image/*" />標籤，在IOS中能夠直接調啟相機和相簿，但是在Android中只能調啟相簿而不能調啟相機。

嘗試過，自己定義一個 JavaScriptInterface ，定義方法調啟相機相簿，獲取圖片後回傳給前端網頁。但是這裡有個問題，傳輸過程比較耗時，app會出現卡頓的情況。

網上查詢答案，找到一篇博文，解決了這個問題，而且不需要額外的JavaScriptInterface ：

方案

mCsiiWebView.setWebChromeClient(new WebChromeClient() {
            @Override
            public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, FileChooserParams fileChooserParams) {
                mUploadCallbackAboveL = filePathCallback;
                take();
                return true;
            }

            //<3.0
            public void openFileChooser(ValueCallback<Uri> uploadMsg) {
                mUploadMessage = uploadMsg;
                take();
            }
            //>3.0+
            public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType) {
                mUploadMessage = uploadMsg;
                take();
            }
            //>4.1.1
            public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {
                mUploadMessage = uploadMsg;
                take();
            }
        });
 

 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == FILECHOOSER_RESULTCODE) {
            if (null == mUploadMessage && null == mUploadCallbackAboveL) return;
            Uri result = data == null || resultCode != RESULT_OK ? null : data.getData();
            if (mUploadCallbackAboveL != null) {
                onActivityResultAboveL(requestCode, resultCode, data);
            } else if (mUploadMessage != null) {
                Log.e("result", result + "");
                if (result == null) {
                    mUploadMessage.onReceiveValue(imageUri);
                    mUploadMessage = null;
                    Log.e("imageUri", imageUri + "");
                } else {
                    mUploadMessage.onReceiveValue(result);
                    mUploadMessage = null;
                }
            }
        }
    }

    @SuppressWarnings("null")
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    private void onActivityResultAboveL(int requestCode, int resultCode, Intent data) {
        if (requestCode != FILECHOOSER_RESULTCODE || mUploadCallbackAboveL == null) {
            return;
        }

        Uri[] results = null;
        if (resultCode == Activity.RESULT_OK) {
            if (data == null) {
                results = new Uri[]{imageUri};
            } else {
                String dataString = data.getDataString();
                ClipData clipData = data.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)};
            }
        }
        if (results != null) {
            mUploadCallbackAboveL.onReceiveValue(results);
            mUploadCallbackAboveL = null;
        } else {
            mUploadCallbackAboveL.onReceiveValue(null);
            mUploadCallbackAboveL = null;
        }
        return;
    }

    private void take() {
        File imageStorageDir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "MyApp");
        if (!imageStorageDir.exists()) {
            imageStorageDir.mkdirs();
        }
        File file = new File(imageStorageDir + File.separator + "IMG_" + String.valueOf(System.currentTimeMillis()) + ".jpg");
        imageUri = Uri.fromFile(file);
        final List<Intent> cameraIntents = new ArrayList<Intent>();
        final Intent captureIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
        final PackageManager packageManager = getPackageManager();
        final List<ResolveInfo> listCam = packageManager.queryIntentActivities(captureIntent, 0);
        for (ResolveInfo res : listCam) {
            final String packageName = res.activityInfo.packageName;
            final Intent i = new Intent(captureIntent);
            i.setComponent(new ComponentName(res.activityInfo.packageName, res.activityInfo.name));
            i.setPackage(packageName);
            i.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
            cameraIntents.add(i);
        }
        Intent i = new Intent(Intent.ACTION_GET_CONTENT);
        i.addCategory(Intent.CATEGORY_OPENABLE);
        i.setType("image/*");
        Intent chooserIntent = Intent.createChooser(i, "Image Chooser");
        chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, cameraIntents.toArray(new Parcelable[]{}));
        startActivityForResult(chooserIntent, FILECHOOSER_RESULTCODE);
    }

    private ValueCallback<Uri[]> mUploadCallbackAboveL;
    private Uri imageUri;
    private ValueCallback<Uri>   mUploadMessage;
    private final static int FILECHOOSER_RESULTCODE = 2;