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[英]How to request permission to write to removable sd card in Android 5.0 and above
[英]How to check and request read, write permission for sd card in platform >= 23 of Android
我有以下代碼來請求對稱為模擬的外部(共享)存儲的讀、寫權限。 現在我也想讀寫 SD 卡。 但是我在日志中收到錯誤“權限被拒絕”。
//We are calling this method to check the read permission status
public boolean isReadWriteStorageAllowed() {
//Getting the permission status
int resultRead = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE);
int resultWrite = ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);
//If permission is granted returning true
if (resultRead == PackageManager.PERMISSION_GRANTED && resultWrite == PackageManager.PERMISSION_GRANTED)
return true;
//If permission is not granted returning false
return false;
}
public void requestStoragePermission(int code){
if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
}
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, code);
}
錯誤日志如下
10-12 14:23:03.998 8550-8550/com.free W/System.err: java.io.FileNotFoundException: /storage/8E14-3919/database.db (Permission denied)
10-12 14:23:03.998 8550-8550/com.free W/System.err: at java.io.FileOutputStream.open(Native Method)
10-12 14:23:03.998 8550-8550/com.free W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:221)
10-12 14:23:03.998 8550-8550/com. free W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:108)
10-12 14:23:03.998 8550-8550/com.free W/System.err: at com. DatabaseManage.exportDatabase(DatabaseManage.java:140)
10-12 14:23:03.998 8550-8550/com.free W/System.err: at com. DatabaseManage.access$000(DatabaseManage.java:50)
10-12 14:23:03.998 8550-8550/com.free W/System.err: at com. DatabaseManage$1.onClick(DatabaseManage.java:106)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at com.android.internal.app.AlertController$AlertParams$3.onItemClick(AlertController.java:1244)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.widget.AdapterView.performItemClick(AdapterView.java:339)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.widget.AbsListView.performItemClick(AbsListView.java:1695)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.widget.AbsListView$PerformClick.run(AbsListView.java:4171)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.widget.AbsListView$13.run(AbsListView.java:6772)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.os.Handler.handleCallback(Handler.java:751)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.os.Handler.dispatchMessage(Handler.java:95)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.os.Looper.loop(Looper.java:154)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6692)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at java.lang.reflect.Method.invoke(Native Method)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
10-12 14:23:03.999 8550-8550/com.free W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)
我的問題是“如果詢問外部存儲的存儲權限”也會授予“sd 卡”的權限? 如果沒有,那么我的代碼有什么問題或者我錯過了什么? 我需要一個解決方案!
代碼如下
public void exportDB(){
int size, pathSize = 0;
String[] storageLocations = null;
final File dbFile = context.getDatabasePath(DATABASE_NAME);//existing database file path
File device = Environment.getExternalStorageDirectory();//device storage
String[] sdCard = getExternalStorageDirectories();//sd cards
size = sdCard.length;
if(size == 0)
pathSize = 0;
else if(size > 0)
pathSize = size + 1;
pathForExports = new String[pathSize];
storageLocations = new String[pathSize];
if(sdCard.length == 0){
pathForExports[0] = device.getAbsolutePath() + "/" + DATABASE_NAME;
storageLocations[0] = "1) Device Storage";
}
else if(sdCard.length > 0) {
pathForExports[0] = device.getAbsolutePath() + "/" + DATABASE_NAME;
storageLocations[0] = "1) Device Storage";
for (int i=0;i<sdCard.length; i++) {
File file = new File(sdCard[i]);
pathForExports[i+1] = file.getAbsolutePath() + "/" + DATABASE_NAME;
if(sdCard.length > 1) {
storageLocations[i+1] = (i+2) + ") Sd Card - " + (i+1);
}
else
storageLocations[i+1] = (i+2) + ") Sd Card";
}
}
//File file = new File(Environment.getExternalStorageDirectory() + File.separator + SAMPLE_DB_NAME);
AlertDialog.Builder builder = new AlertDialog.Builder(context);
builder.setTitle("Choose Export Location");
builder.setItems(pathForExports, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
exportDatabase(dbFile, which);
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
private void exportDatabase(File dbFile, int whichButton) {
FileChannel source = null;
FileChannel destination = null;
try {
source = new FileInputStream(dbFile).getChannel();
destination = new FileOutputStream(pathForExports[whichButton]).getChannel();
destination.transferFrom(source, 0, source.size());
source.close();
destination.close();
if(whichButton == 0)
alert("Database is exported to device storage");
else
alert("Database is exported to sd Card");
} catch(IOException e) {
e.printStackTrace();
if(whichButton == 0)
alert("Failed to export database to device storage");
else
alert("Failed to export database to sd card");
}
}
/storage/8E14-3919/database.db .
即使您擁有外部存儲的所有權限,您仍然無法在該位置的微型 SD 卡上進行寫入。
您只能在卡上的應用程序特定目錄中寫入。
要找到該路徑,請使用 getExternalFilesDirs()。 如果幸運的話,它是返回的條目之一。
對你來說,路徑看起來像
/storage/8E14-3919/Android/data/<packagename>/files
看看文件瀏覽器應用程序。 它可能已經在那里了。
如果您想在卡上的任何地方寫入,請使用存儲訪問框架。
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