默認情況下情況下，
在一個帶有input tpye=file標簽的Html頁面，
使用
Android的WebView是不能夠支持上傳文件的
（在iOS和微信上完全正常工作）
。而這個，也是在我們的前端工程師告知之后才了解的。因為Android的每個版本WebView的實現有差異，因此需要對不同版本去適配。
主要思路是重寫WebChromeClient，然后在Activity中接收選擇到的文件Uri，傳給頁面去上傳就可以了。
由於不同版本的差別，Android 5.0以下的版本，ValueCallback 的onReceiveValue接收的參數類型是
Uri, 5.0及以上版本接收的是
Uri數組，在傳值的時候需要注意。
選擇文件會使用系統提供的組件或者其他支持的app，返回的uri有的直接是文件的url，有的是contentprovider的uri，因此我們需要統一處理一下，轉成文件的uri。
調用getPath可以將Uri轉成真實文件的Path，然后可以自己生成文件的Uri
WebView設置WebChromeClient
重寫WebChromeClient中關於文件選擇的方法，onShowFileChooser和openFileChooser。(項目中只需要選擇圖片，所以加上了圖片過濾。)
private WebChromeClient mWebChromeClient = new WebChromeClient() {
// android 5.0 這里需要使用android5.0 sdk
public boolean onShowFileChooser(WebView webView, ValueCallback<Uri[]> filePathCallback, WebChromeClient.FileChooserParams fileChooserParams) {
if (mFilePathCallback != null) mFilePathCallback.onReceiveValue(null);
mFilePathCallback = filePathCallback;
/**
Open Declaration String android.provider.MediaStore.ACTION_IMAGE_CAPTURE = "android.media.action.IMAGE_CAPTURE"
Standard Intent action that can be sent to have the camera application capture an image and return it.
The caller may pass an extra EXTRA_OUTPUT to control where this image will be written.
If the EXTRA_OUTPUT is not present, then a small sized image is returned as a Bitmap object in the extra field.
This is useful for applications that only need a small image.
If the EXTRA_OUTPUT is present, then the full-sized image will be written to the Uri value of EXTRA_OUTPUT.
As of android.os.Build.VERSION_CODES.LOLLIPOP, this uri can also be supplied through android.content.Intent.setClipData(ClipData).
If using this approach, you still must supply the uri through the EXTRA_OUTPUT field for compatibility with old applications.
If you don't set a ClipData, it will be copied there for you when calling Context.startActivity(Intent).
See Also:EXTRA_OUTPUT
標准意圖，被發送到相機應用程序捕獲一個圖像，並返回它。通過一個額外的extra_output控制這個圖像將被寫入。如果extra_output是不存在的，
那么一個小尺寸的圖像作為位圖對象返回。如果extra_output是存在的，那么全尺寸的圖像將被寫入extra_output URI值。
*/
Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
File photoFile = null;// Create the File where the photo should go
try {
//設置MediaStore.EXTRA_OUTPUT路徑，相機拍照寫入的全路徑
photoFile = createImageFile();
takePictureIntent.putExtra("PhotoPath", mCameraPhotoPath);
} catch (Exception ex) {
// Error occurred while creating the File
Log.e("WebViewSetting", "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));
System.out.println(mCameraPhotoPath);
} 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 };
System.out.println(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;
}
//The undocumented magic method override
//Eclipse will swear at you if you try to put @Override here
// For Android 3.0+
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback<Uri> uploadMsg) {
Log.d("bqt", "openFileChooser1");
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
WebViewActivity.this.startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILECHOOSER_RESULTCODE);
}
// For Android 3.0+
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback uploadMsg, String acceptType) {
Log.d("bqt", "openFileChooser2");
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
WebViewActivity.this.startActivityForResult(Intent.createChooser(i, "Image Chooser"), FILECHOOSER_RESULTCODE);
}
//For Android 4.1
@SuppressWarnings("unused")
public void openFileChooser(ValueCallback<Uri> uploadMsg, String acceptType, String capture) {
Log.d("bqt", "openFileChooser3");
mUploadMessage = uploadMsg;
Intent i = new Intent(Intent.ACTION_GET_CONTENT);
i.addCategory(Intent.CATEGORY_OPENABLE);
i.setType("image/*");
WebViewActivity.this.startActivityForResult(Intent.createChooser(i, "Image Chooser"), WebViewActivity.FILECHOOSER_RESULTCODE);
}
};
選擇結果的回調
在onActivityResult中獲取對應的選取文件的返回結果
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == FILECHOOSER_RESULTCODE) {
if (null == mUploadMessage) return;
Uri result = data == null || resultCode != RESULT_OK ? null : data.getData();
if (result != null) {
String imagePath = ImageFilePath.getPath(this, result);
if (!TextUtils.isEmpty(imagePath)) result = Uri.parse("file:///" + imagePath);
}
mUploadMessage.onReceiveValue(result);
mUploadMessage = null;
} else if (requestCode == INPUT_FILE_REQUEST_CODE && mFilePathCallback != null) {
// 5.0的回調
Uri[] results = null;
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;
} else {
super.onActivityResult(requestCode, resultCode, data);
}
}
文件路徑的獲取
返回文件的解析，因為html頁面需要的是文件，所以客戶端需要返回的是對應文件的路徑。這樣，就會存在一個問題，在Android 4.4上，通過文件選擇返回的結果都是對應以content開頭格式的對應的路徑。這就得需要咱們來進行判斷，最終都需要轉回成以file開頭對應的格式文件。下面，我封裝成了一個ImageFilePath的類，通過調用getPath方法來獲取最終的結果。這個類的方法如下：
public class ImageFilePath {
/**
* Method for return file path of Gallery image
*/
public static String getPath(final Context context, final Uri uri) {
// check here to KITKAT or new version
boolean isKitKat = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
// DocumentProvider
if (isKitKat && DocumentsContract.isDocumentUri(context, uri)) {
// ExternalStorageProvider
if (isExternalStorageDocument(uri)) {
String docId = DocumentsContract.getDocumentId(uri);
String[] split = docId.split(":");
String type = split[0];
if ("primary".equalsIgnoreCase(type)) return Environment.getExternalStorageDirectory() + "/" + split[1];
}
// DownloadsProvider
else if (isDownloadsDocument(uri)) {
String id = DocumentsContract.getDocumentId(uri);
Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"), Long.valueOf(id));
return getDataColumn(context, contentUri, null, null);
}
// MediaProvider
else if (isMediaDocument(uri)) {
String docId = DocumentsContract.getDocumentId(uri);
String[] split = docId.split(":");
String type = split[0];
Uri contentUri = null;
if ("image".equals(type)) contentUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
else if ("video".equals(type)) contentUri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
else if ("audio".equals(type)) contentUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
String selection = "_id=?";
String[] selectionArgs = new String[] { split[1] };
return getDataColumn(context, contentUri, selection, selectionArgs);
}
}
// MediaStore (and general)
else if ("content".equalsIgnoreCase(uri.getScheme())) {
// Return the remote address
if (isGooglePhotosUri(uri)) return uri.getLastPathSegment();
return getDataColumn(context, uri, null, null);
}
// File
else if ("file".equalsIgnoreCase(uri.getScheme())) return uri.getPath();
return null;
}
/**
* Get the value of the data column for this Uri. This is useful for MediaStore Uris, and other file-based ContentProviders.
* @param context The context.
* @param uri The Uri to query.
* @param selection (Optional) Filter used in the query.
* @param selectionArgs (Optional) Selection arguments used in the query.
* @return The value of the _data column, which is typically a file path.
*/
public static String getDataColumn(Context context, Uri uri, String selection, String[] selectionArgs) {
Cursor cursor = null;
String column = "_data";
String[] projection = { column };
try {
cursor = context.getContentResolver().query(uri, projection, selection, selectionArgs, null);
if (cursor != null && cursor.moveToFirst()) {
int index = cursor.getColumnIndexOrThrow(column);
return cursor.getString(index);
}
} finally {
if (cursor != null) cursor.close();
}
return null;
}
public static boolean isExternalStorageDocument(Uri uri) {
return "com.android.externalstorage.documents".equals(uri.getAuthority());
}
public static boolean isDownloadsDocument(Uri uri) {
return "com.android.providers.downloads.documents".equals(uri.getAuthority());
}
public static boolean isMediaDocument(Uri uri) {
return "com.android.providers.media.documents".equals(uri.getAuthority());
}
public static boolean isGooglePhotosUri(Uri uri) {
return "com.google.android.apps.photos.content".equals(uri.getAuthority());
}
}
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