我得到了
open failed: EACCES(权限被拒绝)
myOutput = new FileOutputStream(outFileName);
我检查了根目录，并尝试了android.permission.WRITE_EXTERNAL_STORAGE。
我该如何解决这个问题?
try {
InputStream myInput;
myInput = getAssets().open("XXX.db");
// Path to the just created empty db
String outFileName = "/data/data/XX/databases/"
+ "XXX.db";
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// Transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
buffer = null;
outFileName = null;
}
catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
在我的例子中，我使用的是一个文件选择器库，它返回到外部存储的路径，但它从/root/开始。即使在运行时授予WRITE_EXTERNAL_STORAGE权限，我仍然得到错误EACCES(权限被拒绝)。
因此，使用Environment.getExternalStorageDirectory()来获取外部存储的正确路径。
例子:
无法写入:/root/storage/emulated/0/newfile.txt
可以写:/storage/emulated/0/newfile.txt
boolean externalStorageWritable = isExternalStorageWritable();
File file = new File(filePath);
boolean canWrite = file.canWrite();
boolean isFile = file.isFile();
long usableSpace = file.getUsableSpace();
Log.d(TAG, "externalStorageWritable: " + externalStorageWritable);
Log.d(TAG, "filePath: " + filePath);
Log.d(TAG, "canWrite: " + canWrite);
Log.d(TAG, "isFile: " + isFile);
Log.d(TAG, "usableSpace: " + usableSpace);
/* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
输出1:
externalStorageWritable: true
filePath: /root/storage/emulated/0/newfile.txt
isFile: false
usableSpace: 0
输出2:
externalStorageWritable: true
filePath: /storage/emulated/0/newfile.txt
isFile: true
usableSpace: 1331007488
添加gradle依赖项
implementation 'com.karumi:dexter:4.2.0'
在主活动中添加以下代码。
import com.karumi.dexter.Dexter;
import com.karumi.dexter.MultiplePermissionsReport;
import com.karumi.dexter.PermissionToken;
import com.karumi.dexter.listener.PermissionRequest;
import com.karumi.dexter.listener.multi.MultiplePermissionsListener;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_splash);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
checkMermission();
}
}, 4000);
}
private void checkMermission(){
Dexter.withActivity(this)
.withPermissions(
android.Manifest.permission.READ_EXTERNAL_STORAGE,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE,
android.Manifest.permission.ACCESS_NETWORK_STATE,
Manifest.permission.INTERNET
).withListener(new MultiplePermissionsListener() {
@Override
public void onPermissionsChecked(MultiplePermissionsReport report) {
if (report.isAnyPermissionPermanentlyDenied()){
checkMermission();
} else if (report.areAllPermissionsGranted()){
// copy some things
} else {
checkMermission();
}
}
@Override
public void onPermissionRationaleShouldBeShown(List<PermissionRequest> permissions, PermissionToken token) {
token.continuePermissionRequest();
}
}).check();
}
