Android应用程序为了用户的安全,引入相关的权限机制,如何在应用中有效检查权限,而不需要每个地方都重复性的进行检查、请求、回调的编码呢?
思路:应用中A activity进行权限检查,无权限启动一个专门的权限activity,申请权限,完成后,再启动原A activity.
1. 自定义基类 RequestPermissionsActivityBase
/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jxh.activities;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Trace;
import android.support.v4.app.ActivityCompat;
import android.util.Log;
import java.util.ArrayList;
import java.util.Arrays;
/**
* Activity that asks the user for all {@link #getPermissions} if any are missing.
*
* NOTE: As a result of b/22095159, this can behave oddly in the case where the final permission
* you are requesting causes an application restart.
*/
public abstract class RequestPermissionsActivityBase extends Activity
implements ActivityCompat.OnRequestPermissionsResultCallback {
protected static final String TAG = "RequestPermissionsActivityBase";
public static final String PREVIOUS_ACTIVITY_INTENT = "previous_intent";
/** Whether the permissions activity was already started. */
protected static final String EXTRA_STARTED_PERMISSIONS_ACTIVITY =
"started_permissions_activity";
protected static final String EXTRA_IS_CALLER_SELF = "is_caller_self";
protected static final int PERMISSIONS_REQUEST_ALL_PERMISSIONS = 1;
/**
* @return list of permissions that are needed in order for {@link #PREVIOUS_ACTIVITY_INTENT}
* to operate. You only need to return a single permission per permission group you care about.
*/
protected abstract String[] getPermissions();
protected Intent mPreviousActivityIntent;
/** If true then start the target activity "for result" after permissions are granted. */
protected boolean mIsCallerSelf;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mPreviousActivityIntent = (Intent) getIntent().getExtras().get(PREVIOUS_ACTIVITY_INTENT);
mIsCallerSelf = getIntent().getBooleanExtra(EXTRA_IS_CALLER_SELF, false);
// Only start a requestPermissions() flow when first starting this activity the first time.
// The process is likely to be restarted during the permission flow (necessary to enable
// permissions) so this is important to track.
if (savedInstanceState == null) {
requestPermissions();
}
}
/**
* If any permissions the app needs are missing, open an Activity
* to prompt the user for these permissions. Moreover, finish the current activity.
*
* This is designed to be called inside {@link android.app.Activity#onCreate}
*/
protected static boolean startPermissionActivity(Activity activity,
String[] requiredPermissions, Class<?> newActivityClass) {
return startPermissionActivity(activity, requiredPermissions, /* isCallerSelf */ false,
newActivityClass);
}
protected static boolean startPermissionActivity(Activity activity,
String[] requiredPermissions, boolean isCallerSelf, Class<?> newActivityClass) {
if (!hasPermissions(activity, requiredPermissions)) {
final Intent intent = new Intent(activity, newActivityClass);
activity.getIntent().putExtra(EXTRA_STARTED_PERMISSIONS_ACTIVITY, true);
intent.putExtra(PREVIOUS_ACTIVITY_INTENT, activity.getIntent());
intent.putExtra(EXTRA_IS_CALLER_SELF, isCallerSelf);
activity.startActivity(intent);
Log.d(TAG," startPermissionActivity() ... , finish activity: "+activity);
activity.finish();
return true;
}
return false;
}
protected boolean isAllGranted(String permissions[], int[] grantResult) {
for (int i = 0; i < permissions.length; i++) {
if (grantResult[i] != PackageManager.PERMISSION_GRANTED
&& isPermissionRequired(permissions[i])) {
return false;
}
}
return true;
}
private boolean isPermissionRequired(String p) {
return Arrays.asList(getPermissions()).contains(p);
}
private void requestPermissions() {
Trace.beginSection("requestPermissions");
try {
// Construct a list of missing permissions
final ArrayList<String> unsatisfiedPermissions = new ArrayList<>();
for (String permission : getPermissions()) {
if (checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) {
unsatisfiedPermissions.add(permission);
}
}
if (unsatisfiedPermissions.size() == 0) {
throw new RuntimeException("Request permission activity was called even"
+ " though all permissions are satisfied.");
}
ActivityCompat.requestPermissions(
this,
unsatisfiedPermissions.toArray(new String[unsatisfiedPermissions.size()]),
PERMISSIONS_REQUEST_ALL_PERMISSIONS);
} finally {
Trace.endSection();
}
}
protected static boolean hasPermissions(Context context, String[] permissions) {
Trace.beginSection("hasPermission");
try {
for (String permission : permissions) {
if (context.checkSelfPermission(permission) != PackageManager.PERMISSION_GRANTED) {
return false;
}
}
return true;
} finally {
Trace.endSection();
}
}
}
2. 自定义子类 RequestPermissionsActivity
/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jxh.activities;
import android.Manifest.permission;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.widget.Toast;
import com.sprd.fileexplorer.R;
import java.util.ArrayList;
import java.util.List;
/**
* Activity that requests permissions needed for activities exported from Our App by referencing Google Contacts App.
*/
public class RequestPermissionsActivity extends RequestPermissionsActivityBase {
private static final String[] REQUIRED_PERMISSIONS = new String[] {
permission.READ_EXTERNAL_STORAGE,
permission.WRITE_EXTERNAL_STORAGE
};
public static boolean hasRequiredPermissions(Context context) {
return hasPermissions(context, REQUIRED_PERMISSIONS);
}
@Override
protected String[] getPermissions() {
return REQUIRED_PERMISSIONS;
}
public static boolean startPermissionActivityIfNeeded(Activity activity) {
return startPermissionActivity(activity,
REQUIRED_PERMISSIONS,
RequestPermissionsActivity.class);
}
@Override
public void onRequestPermissionsResult(
int requestCode, String permissions[], int[] grantResults) {
switch (requestCode) {
case PERMISSIONS_REQUEST_ALL_PERMISSIONS:
if (permissions != null && permissions.length > 0
&& isAllGranted(permissions, grantResults)) {
mPreviousActivityIntent.setFlags(Intent.FLAG_ACTIVITY_NO_ANIMATION);
if (mIsCallerSelf) {
startActivityForResult(mPreviousActivityIntent, 0);
} else {
startActivity(mPreviousActivityIntent);
}
finish();
overridePendingTransition(0, 0);
} else {
Toast.makeText(this, R.string.error_permissions, Toast.LENGTH_SHORT).show();
finish();
}
break;
default:
break;
}
}
}
3. 使用方法
应用Activity的onCreate()使用:
if(!RequestPermissionsActivity.hasRequiredPermissions(this)){
RequestPermissionsActivity.startPermissionActivityIfNeeded(this);
return;
}