java.io.FileNotFoundException: /storage/emulated/0/downloadedfilem.jpg（权限被拒绝）
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java.io.FileNotFoundException: /storage/emulated/0/downloadedfilem.jpg (Permission denied)
提问by Midhun Pottammal
i am trying to download and store image using Async task in android , when clicking download button getting following error.
我试图在 android 中使用异步任务下载和存储图像，当单击下载按钮时出现以下错误。
W/System.err: java.io.FileNotFoundException: /storage/emulated/0/downloadedfilem.jpg (Permission denied)
12-07 11:01:00.120 28478-28540/myoracle.com.quotes W/System.err: at java.io.FileOutputStream.open(Native Method)
12-07 11:01:00.120 28478-28540/myoracle.com.quotes W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
12-07 11:01:00.120 28478-28540/myoracle.com.quotes W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:108)
12-07 11:01:00.120 28478-28540/myoracle.com.quotes W/System.err: at myoracle.com.quotes.WallpaperDeatilsActivity$ImageDownload.doInBackground(WallpaperDeatilsActivity.java:113)
12-07 11:01:00.120 28478-28540/myoracle.com.quotes W/System.err: at myoracle.com.quotes.WallpaperDeatilsActivity$ImageDownload.doInBackground(WallpaperDeatilsActivity.java:91)
WallpaperActivity.java
壁纸活动.java
class ImageDownload extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... params) {
int count;
try {
String root = Environment.getExternalStorageDirectory().toString();
System.out.println("Downloading");
URL url = new URL(params[0]);
URLConnection conection = url.openConnection();
conection.connect();
// getting file length
int lenghtOfFile = conection.getContentLength();
// input stream to read file - with 8k buffer
InputStream input = new BufferedInputStream(url.openStream(), 8192);
// Output stream to write file
System.out.println(root);
OutputStream output = new FileOutputStream(root+"/downloadedfilem.jpg");
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
// writing data to file
output.write(data, 0, count);
System.out.println(count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
e.printStackTrace();
}
- Android Target Api 7.1.1
- Android 目标 API 7.1.1
Permissions added in manifest
清单中添加的权限
android.permission.READ_EXTERNAL_STORAGE
android.permission.WRITE_EXTERNAL_STORAGE
android.permission.READ_EXTERNAL_STORAGE
android.permission.WRITE_EXTERNAL_STORAGE
回答by Dharmishtha
You need to add runtime permission for OS Marshmallow or above. Add this code for permission to allow run time operation in splash activity in onCreate or before download process of image.
您需要为 OS Marshmallow 或更高版本添加运行时权限。添加此代码以获得允许在 onCreate 或图像下载过程之前的启动活动中运行时操作的权限。
if (!checkPermission()) {
openActivity();
} else {
if (checkPermission()) {
requestPermissionAndContinue();
} else {
openActivity();
}
}
Add this method outside onCreate
在外面添加这个方法 onCreate
private static final int PERMISSION_REQUEST_CODE = 200;
private boolean checkPermission() {
return ContextCompat.checkSelfPermission(this, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
&& ContextCompat.checkSelfPermission(this, READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
;
}
private void requestPermissionAndContinue() {
if (ContextCompat.checkSelfPermission(this, WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED
&& ContextCompat.checkSelfPermission(this, READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(this, WRITE_EXTERNAL_STORAGE)
&& ActivityCompat.shouldShowRequestPermissionRationale(this, READ_EXTERNAL_STORAGE)) {
AlertDialog.Builder alertBuilder = new AlertDialog.Builder(this);
alertBuilder.setCancelable(true);
alertBuilder.setTitle(getString(R.string.permission_necessary));
alertBuilder.setMessage(R.string.storage_permission_is_encessary_to_wrote_event);
alertBuilder.setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
public void onClick(DialogInterface dialog, int which) {
ActivityCompat.requestPermissions(SplashActivity.this, new String[]{WRITE_EXTERNAL_STORAGE
, READ_EXTERNAL_STORAGE}, PERMISSION_REQUEST_CODE);
}
});
AlertDialog alert = alertBuilder.create();
alert.show();
Log.e("", "permission denied, show dialog");
} else {
ActivityCompat.requestPermissions(SplashActivity.this, new String[]{WRITE_EXTERNAL_STORAGE,
READ_EXTERNAL_STORAGE}, PERMISSION_REQUEST_CODE);
}
} else {
openActivity();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == PERMISSION_REQUEST_CODE) {
if (permissions.length > 0 && grantResults.length > 0) {
boolean flag = true;
for (int i = 0; i < grantResults.length; i++) {
if (grantResults[i] != PackageManager.PERMISSION_GRANTED) {
flag = false;
}
}
if (flag) {
openActivity();
} else {
finish();
}
} else {
finish();
}
} else {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
}
}
private void openActivity() {
//add your further process after giving permission or to download images from remote server.
}
回答by Rakesh
After Android 6.0 Marshmellow you need Runtime Permissions to access user private data like Local storage. https://developer.android.com/training/permissions/requesting.html
在 Android 6.0 Marshmellow 之后，您需要运行时权限才能访问本地存储等用户私有数据。https://developer.android.com/training/permissions/requesting.html
