在我的应用程序中,我想获得用户在外部存储上读取和写入数据的权限,我已将权限标签放入我的清单中,如下所示。 但是,当安装应用程序或运行时,以及需要读取或写入存储时,不会从用户那里获取任何权限,并且读取和写入内存不起作用,直到我手动转到设置应用程序访问并启用对内存的访问。
我的清单是这样的:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="javadi60.saber.storeassistant">
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
android:allowBackup="true"
android:dialogTheme="@style/CustomDialog"
android:icon="@mipmap/myappicon"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".insertData" />
<activity android:name=".setting" />
<activity android:name=".dellAll" />
<activity android:name=".reports" />
<activity android:name=".login" />
</application>
</manifest>
在 android API >= 23 中,您需要在运行时请求权限。看看这里
类似这样的事情
// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(thisActivity,
Manifest.permission.WRITE_EXTERNAL_STORAGE)
!= PackageManager.PERMISSION_GRANTED) {
// Permission is not granted
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
} else {
// No explanation needed; request the permission
ActivityCompat.requestPermissions(thisActivity,
new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
MY_PERMISSIONS_WRITE_EXTERNAL_STORAGE);
// MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
// app-defined int constant. The callback method gets the
// result of the request.
}
} else {
// Permission has already been granted
}
但是,Ted 权限库是一个很好的库,可以避免此类样板代码。
//call back after permission granted
PermissionListener permissionlistener = new PermissionListener() {
@Override
public void onPermissionGranted() {
Toast.makeText(MainActivity.this, "Permission Granted", Toast.LENGTH_SHORT).show();
}
@Override
public void onPermissionDenied(List<String> deniedPermissions) {
Toast.makeText(MainActivity.this, "Permission Denied\n" + deniedPermissions.toString(), Toast.LENGTH_SHORT).show();
}
};
//check all needed permissions together
TedPermission.with(this)
.setPermissionListener(permissionlistener)
.setDeniedMessage("If you reject permission,you can not use this service\n\nPlease turn on permissions at [Setting] > [Permission]")
.setPermissions(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE)
.check();
推荐的解决方案:使用 Dexter 或 KotlinPermissions 或 RxPermissions 等权限库。我都用过,还蛮靠谱的。
其他:
在您的活动中写入这些行,只需在 super.onCreate(...) 和 setContentView(...):
之前super.onCreate(savedInstanceState);
// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 1);
}
if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
}
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 1);
}
setContentView(R.layout.activity_main);
现在应该可以了,它解决了我的问题!
棉花糖或以上版本的存储和图库使用的读写权限:
private void requestPermission() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[] {
android.Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_WRITE_PERMISSION);
} else {
openFilePicker();
}
}
要检查权限结果,请使用以下方法:
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[]
permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
switch (requestCode) {
case STORAGE_PERMISSION_REQUEST_CODE:
if (grantResults.length > 0 && permissions[0].equals(Manifest.permission.WRITE_EXTERNAL_STORAGE)) {
// check whether storage permission granted or not.
if (grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// do what you want;
}
}
break;
default:
break;
}
}
从 Android 24 及更高版本开始,您需要运行时权限才能访问设备的某些功能,例如麦克风、摄像头、存储等。使用以下代码检查您是否具有存储权限访问权限
private boolean hasStoragePermission(int requestCode) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, requestCode);
return false;
} else {
return true;
}
} else {
return true;
}
}
它会显示弹出窗口以允许访问,如果它允许执行您的操作
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
if (requestCode == FILE_ATTACHMENT)
attachFile();
}
}
清理该死的项目,重新构建并运行,如果它仍然不起作用......
将此代码添加到您的活动的 onCreate 方法中。删除应用程序,清理项目,构建并运行。另外,不要忘记在清单中添加您想要的权限。 (对于较低的 API 级别,不需要该代码,但从 23 及以上版本开始,您还需要此代码)
private fun requestPermission() {
val permissions = arrayOf(Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.WRITE_EXTERNAL_STORAGE)
this.requestPermissions(permissions, 5)
}
对于 android 6 (api 23) 或更高版本尝试使用 应用程序 -> 清单 -> AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools">
<!-- for >= android 6 api level 23 -->
<uses-permission-sdk-23 android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission-sdk-23 android:name="android.permission.READ_EXTERNAL_STORAGE" />
<application
...