根据这个:http://developer.android.com/preview/features/runtime-permissions.html#coding一个应用程序可以检查运行时权限和请求权限,如果它还没有被授予。弹出如下对话框:
如果用户拒绝一个重要的权限,在我看来,应用程序应该显示一个解释为什么需要权限和什么影响拒绝。该对话框有两个选项:
重试(再次请求许可)
拒绝(应用程序将工作没有该许可)。
但是,如果用户选中“Never ask again”,则不应该显示带有解释的第二个对话框,特别是如果用户之前已经拒绝了一次。
现在的问题是:我的应用程序如何知道用户是否选中了Never ask again?IMO onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults)没有给我这个信息。
第二个问题是:谷歌是否计划在权限对话框中包含一个自定义消息,以解释为什么应用程序需要权限?这样就不会出现第二个对话框,这肯定会带来更好的用户体验。
我在Android m中写了一个权限请求的简写,这段代码还处理了对旧Android版本的向后兼容性。
所有丑陋的代码都被提取到一个片段中,该片段将自己附加到请求权限的活动上。PermissionRequestManager的使用方法如下:
new PermissionRequestManager()
// We need a AppCompatActivity here, if you are not using support libraries you will have to slightly change
// the PermissionReuqestManager class
.withActivity(this)
// List all permissions you need
.withPermissions(android.Manifest.permission.CALL_PHONE, android.Manifest.permission.READ_CALENDAR)
// This Runnable is called whenever the request was successfull
.withSuccessHandler(new Runnable() {
@Override
public void run() {
// Do something with your permissions!
// This is called after the user has granted all
// permissions, we are one a older platform where
// the user does not need to grant permissions
// manually, or all permissions are already granted
}
})
// Optional, called when the user did not grant all permissions
.withFailureHandler(new Runnable() {
@Override
public void run() {
// This is called if the user has rejected one or all of the requested permissions
L.e(this.getClass().getSimpleName(), "Unable to request permission");
}
})
// After calling this, the user is prompted to grant the rights
.request();
来看看:https://gist.github.com/crysxd/385b57d74045a8bd67c4110c34ab74aa
我发现这个问题的方法对我来说有点新鲜。我必须保留一个参考,如果用户曾经选择了一个决定。通过这种方式,如果权限没有被授予,我可以告诉用户是第一次在那里,并且应该提示看到权限弹出,或者用户暂时或永久地拒绝它。
psudocode:
if( granted ) {
// you are set
} else if( requiresRationale() ) {
// in the ui let the user know he has to tap and launch permission
button.onSetClickListener { requestPermission() }
} else if( sharedPreferences.getBoolean("permission", false) ) {
// so user has already decided to deny permission, then it is permanent
launchAppSettings()
} else {
// user's first encounter, request permission
requestPermission()
}
演示文件以GIF格式附在自述文件中。
https://github.com/juanmendez/android-sdk-updates/tree/api/android-permissions/single
这里有一个很好的和简单的方法来检查当前的权限状态:
@Retention(RetentionPolicy.SOURCE)
@IntDef({GRANTED, DENIED, BLOCKED_OR_NEVER_ASKED })
public @interface PermissionStatus {}
public static final int GRANTED = 0;
public static final int DENIED = 1;
public static final int BLOCKED_OR_NEVER_ASKED = 2;
@PermissionStatus
public static int getPermissionStatus(Activity activity, String androidPermissionName) {
if(ContextCompat.checkSelfPermission(activity, androidPermissionName) != PackageManager.PERMISSION_GRANTED) {
if(!ActivityCompat.shouldShowRequestPermissionRationale(activity, androidPermissionName)){
return BLOCKED_OR_NEVER_ASKED;
}
return DENIED;
}
return GRANTED;
}
警告:在用户通过用户提示接受/拒绝权限之前,在第一个应用程序启动时返回BLOCKED_OR_NEVER_ASKED(在sdk 23+设备上)
更新:
Android支持库现在似乎也有一个非常类似的类Android .support.v4.content。PermissionChecker,包含checkSelfPermission(),返回:
public static final int PERMISSION_GRANTED = 0;
public static final int PERMISSION_DENIED = -1;
public static final int PERMISSION_DENIED_APP_OP = -2;
一旦用户标记了“不要再问”,该问题就不能再次显示。
但是可以向用户解释,他之前拒绝了权限,必须在设置中授予权限。并参考他的设置,使用以下代码:
@Override
public void onRequestPermissionsResult(int permsRequestCode, String[] permissions, int[] grantResults) {
if (grantResults.length > 0
&& grantResults[0] == PackageManager.PERMISSION_GRANTED) {
// now, you have permission go ahead
// TODO: something
} else {
if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this,
Manifest.permission.READ_CALL_LOG)) {
// now, user has denied permission (but not permanently!)
} else {
// now, user has denied permission permanently!
Snackbar snackbar = Snackbar.make(findViewById(android.R.id.content), "You have previously declined this permission.\n" +
"You must approve this permission in \"Permissions\" in the app settings on your device.", Snackbar.LENGTH_LONG).setAction("Settings", new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivity(new Intent(android.provider.Settings.ACTION_APPLICATION_DETAILS_SETTINGS, Uri.parse("package:" + BuildConfig.APPLICATION_ID)));
}
});
View snackbarView = snackbar.getView();
TextView textView = (TextView) snackbarView.findViewById(android.support.design.R.id.snackbar_text);
textView.setMaxLines(5); //Or as much as you need
snackbar.show();
}
}
return;
}