先说场景，公司在app上集成推送功能，可是在OPPO手机上一直接收不到推送消息，debug一下发现推送消息可以接受到但是没有吊起通知栏。去设置一看通知栏没给权限。又去oppo开放平台咨询，oppo官方回答如下

咋办呢。。。。。。

首先想到是不是和运行时权限一样，用到时申请一下呢，便尝试了以下方法。

方案一：

通过反射检查通知是否打开，没打开便去申请。

package com.example.jpushdemo;

import android.app.AppOpsManager;
import android.content.Context;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.net.Uri;
import android.provider.Settings;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

/**
 */
public class NotificationsUtils {
   private static final String CHECK_OP_NO_THROW = "checkOpNoThrow";
   private static final String OP_POST_NOTIFICATION = "OP_POST_NOTIFICATION";
   //检测 通知状态 是否已打开
   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 = (int) opPostNotificationValue.get(Integer.class);

         return (
               (int) checkOpNoThrowMethod.invoke(mAppOps, value, uid, pkg) ==
                     AppOpsManager.MODE_ALLOWED);

      } catch (ClassNotFoundException e) {
         e.printStackTrace();
      } catch (NoSuchMethodException e) {
         e.printStackTrace();
      } catch (NoSuchFieldException e) {
         e.printStackTrace();
      } catch (InvocationTargetException e) {
         e.printStackTrace();
      } catch (IllegalAccessException e) {
         e.printStackTrace();
      }
      return false;
   }

   /**
    * 跳转设置页面 去设置通知权限
    * @param context
    */
   public static void toNotificationSetting(Context context) {
      if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {
         Intent intent = new Intent();
         intent.setAction("android.settings.APP_NOTIFICATION_SETTINGS");
         intent.putExtra("app_package", context.getApplicationContext().getPackageName());
         intent.putExtra("app_uid", context.getApplicationInfo().uid);
         context.startActivity(intent);
      } else if (android.os.Build.VERSION.SDK_INT == android.os.Build.VERSION_CODES.KITKAT) {
         Intent intent = new Intent();
         intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);
         intent.addCategory(Intent.CATEGORY_DEFAULT);
         intent.setData(Uri.parse("package:" + context.getApplicationContext().getPackageName()));
         context.startActivity(intent);
      }
   }
}