[英]Write to external storage on Android 7
I want to write to the external storage in my Android app, but I don't seem to get the permissions right. 我想写入我的Android应用程序中的外部存储,但似乎没有正确的权限。 The App runs on Android 7, so I request the permissions on runtime like this:
该应用程序在Android 7上运行,因此我要求在运行时提供如下权限:
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
int ACCESS_EXTERNAL_STORAGE_STATE = 1;
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
ACCESS_EXTERNAL_STORAGE_STATE);
}
permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
if (permission != PackageManager.PERMISSION_GRANTED) {
// We don't have permission so prompt the user
int ACCESS_EXTERNAL_STORAGE_STATE = 1;
ActivityCompat.requestPermissions(this,
new String[]{Manifest.permission.READ_EXTERNAL_STORAGE},
ACCESS_EXTERNAL_STORAGE_STATE);
}
...
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode)
{
case 1: {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED)
{
//reload my activity with permission granted or use the features what required the permission
} else
{
Toast.makeText(this, "The app was not allowed to write to your storage. Hence, it cannot function properly. Please consider granting it this permission", Toast.LENGTH_LONG).show();
}
}
}
}
One observation I made is that onRequestPermissionsResult seems to return that the permission was not granted, but I was also never prompted when starting the app to permit writing to external storage. 我发现,onRequestPermissionsResult似乎返回未授予权限的信息,但是在启动应用程序以允许写入外部存储时也从未提示我。
I set these permissions in the Manifest: 我在清单中设置了以下权限:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application>
The code to write to the storage is here: 写入存储的代码在这里:
public static void appendByteBuffer(byte[] data)
{
String filename = Environment.getExternalStorageDirectory().getAbsolutePath()+"/test.raw";
//filename value is "/storage/emulated/0/test.raw"
File rawAudioFile = new File(filename);
if (!rawAudioFile.exists())
{
try
{
rawAudioFile.createNewFile();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
}
try (FileOutputStream output = new FileOutputStream(filename, true)) {
output.write(data);
} catch (IOException e) {}
}
03-16 14:50:49.988 19145-19306/?
03月16日14:50:49.988 19145-19306 /? W/System.err: java.io.IOException: Permission denied 03-16 14:50:49.988 19145-19306/?
W / System.err:java.io.IOException:权限被拒绝03-16 14:50:49.988 19145-19306 /? W/System.err:
W / System.err:
at java.io.UnixFileSystem.createFileExclusively0(Native Method) 03-16 14:50:49.988 19145-19306/?在java.io.UnixFileSystem.createFileExclusively0(本机方法)03-16 14:50:49.988 19145-19306 /? W/System.err: at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280) 03-16 14:50:49.989 19145-19306/?
W / System.err:位于java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280)03-16 14:50:49.989 19145-19306 /? W/System.err: at java.io.File.createNewFile(File.java:948) 03-16 14:50:49.989 19145-19306/?
W / System.err:位于java.io.File.createNewFile(File.java:948)03-16 14:50:49.989 19145-19306 /? W/System.err: at com.meeter.study.AppUtils.appendByteBuffer(AppUtils.java:76) 03-16 14:50:49.989 19145-19306/?
W / System.err:at com.meeter.study.AppUtils.appendByteBuffer(AppUtils.java:76)03-16 14:50:49.989 19145-19306 /? W/System.err: at
W / System.err:位于
Use ContextCompat
instead of ActivityCompat
for checkSelfPermission
: 将
ContextCompat
代替ActivityCompat
用于checkSelfPermission
:
Replace: 更换:
permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
permission = ActivityCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
With: 带有:
permission = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
permission = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
Then, Add onRequestPermissionsResult
method to handle ALLOW, DENY selection. 然后,添加
onRequestPermissionsResult
方法以处理ALLOW,DENY选择。 Hope this helps. 希望这可以帮助。
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
switch (requestCode) {
case ACCESS_EXTERNAL_STORAGE_STATE: {
// If request is cancelled, the result arrays are empty.
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// Write to the storage (ex: call appendByteBuffer(byte[] data) here)
} else {
Toast.makeText(getApplicationContext(), "Please grant permission.", Toast.LENGTH_LONG).show();
}
break;
}
}
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