官方文件介紹了兩種獲取RegistrationID的方法：
https://docs.jiguang.cn/jpush/client/Android/android_api/#registrationid-api
//SDK 初次註冊成功後，開發者通過在自定義的 Receiver 裡監聽 Action - cn.jpush.android.intent.REGISTRATION 來獲取對應的 RegistrationID。註冊成功後，也可以通過此函式獲取
public static String getRegistrationID(Context context)

在下看來第一種是誤導，應該在application中才能拿到！！！而不是自定義Receiver!在application中對其進行的初始化！！

 registrationId = JPushInterface.getRegistrationID(this);
         Log.e("1099", "run:--------->registrationId： "+registrationId );

public class MyApplication extends Application {
    public static String registrationId;

    private List<Activity> mList = new LinkedList<Activity>();
    public
 
 static MyApplication instance;
    private static Context context;
    @Override
    public void onCreate() {
        super.onCreate();


        JPushInterface.setDebugMode(true);
        JPushInterface.init(this);

        registrationId = JPushInterface.getRegistrationID(this);
         Log.e("1099"
 
, "run:--------->registrationId： "+registrationId );
        SharePLogin mSharePLogin=new SharePLogin(this);
        mSharePLogin.saveData("registrationId",registrationId);
        Toast.makeText(instance, "registrationId", Toast.LENGTH_SHORT).show();
        instance = this;
        OkHttpClient okHttpClient = new OkHttpClient.Builder()
//                .addInterceptor(new LoggerInterceptor("TAG"))
                .connectTimeout(10000L, TimeUnit.MILLISECONDS)
                .readTimeout(10000L, TimeUnit.MILLISECONDS)
                        //其他配置
                .build();

        OkHttpUtils.initClient(okHttpClient);
        MobclickAgent.setScenarioType(getApplicationContext(), MobclickAgent.EScenarioType.E_UM_NORMAL);
    }
    public MyApplication() {
    }

    public static String getRegistrationId() {
        return registrationId;
    }

    public static void setRegistrationId(String registrationId) {
        MyApplication.registrationId = registrationId;

    }


    public synchronized static MyApplication getInstance() {
        if (null == instance) {
            instance = new MyApplication();
        }
        return instance;
    }
    public static Context getContext(){
        return context;
    }



    // add Activity
    public void addActivity(Activity activity) {
        System.out.println("add");
        mList.add(activity);
    }
    public void exitOther() {
        for (int i = 0; i < mList.size() - 1; i++) {
            mList.get(i).finish();
        }
    }
    public void exit() {
        try {
            for (Activity activity : mList) {
                if (activity != null)
                    activity.finish();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            System.exit(0);
        }
    }

    public void onLowMemory() {
        super.onLowMemory();
        System.gc();
    }

}