Android 应用获取通知栏权限是否开启，并跳转设置界面

因为项目要用到推送功能，所以需要知道用户是否开启了通知栏的权限，并且可以方便直接跳转到权限设置以便用户进行开启。

1. 获取权限工具类

public class NotificationsUtils {

    private static final String CHECK_OP_NO_THROW = "checkOpNoThrow";
    private static final String OP_POST_NOTIFICATION = "OP_POST_NOTIFICATION";

    @SuppressLint("NewApi")
    public static boolean isNotificationEnabled(Context context) {

        AppOpsManager mAppOps = 
                (AppOpsManager) context.getSystemService(Context.APP_OPS_SERVICE);

        ApplicationInfo appInfo = context.getApplicationInfo();
        String pkg = context.getApplicationContext().getPackageName();
        int uid = appInfo.uid;
        Class appOpsClass = null;

        /* Context.APP_OPS_MANAGER */
        try {
            appOpsClass = Class.forName(AppOpsManager.class.getName());

            Method checkOpNoThrowMethod = 
                    appOpsClass.getMethod(CHECK_OP_NO_THROW, 
                    Integer.TYPE, Integer.TYPE, String.class);

            Field opPostNotificationValue = appOpsClass.getDeclaredField(OP_POST_NOTIFICATION);
            int value = (Integer) opPostNotificationValue.get(Integer.class);

            return ((Integer) checkOpNoThrowMethod.invoke(mAppOps, value, uid, pkg) == 
                     AppOpsManager.MODE_ALLOWED);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return false;
    }
}

2. 跳转到应用权限设置界面

    if (!NotificationsUtils.isNotificationEnabled(this)) {
            final AlertDialog dialog = new AlertDialog.Builder(this).create();
            dialog.show();

            View view = View.inflate(this, R.layout.dialog, null);
            dialog.setContentView(view);

            TextView context = (TextView) view.findViewById(R.id.tv_dialog_context);
            context.setText("检测到您没有打开通知权限，是否去打开");

            TextView confirm = (TextView) view.findViewById(R.id.btn_confirm);
            confirm.setText("确定");
            confirm.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    dialog.cancel();
                    Intent localIntent = new Intent();
                    localIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                    if (Build.VERSION.SDK_INT >= 9) {
                        localIntent.setAction("android.settings.APPLICATION_DETAILS_SETTINGS");
                        localIntent.setData(Uri.fromParts("package", MainActivity.this.getPackageName(), null));
                    } else if (Build.VERSION.SDK_INT <= 8) {
                        localIntent.setAction(Intent.ACTION_VIEW);

                        localIntent.setClassName("com.android.settings",
                                "com.android.settings.InstalledAppDetails");

                        localIntent.putExtra("com.android.settings.ApplicationPkgName",
                                MainActivity.this.getPackageName());
                    }
                    startActivity(localIntent);
                }
            });

            TextView cancel = (TextView) view.findViewById(R.id.btn_off);
            cancel.setOnClickListener(new View.OnClickListener() {
                public void onClick(View v) {
                    dialog.cancel();
                }
            });
      }