Activity与Service通信的方式

1. 使用intent进行传值 效率不高

MainActivity.java
    //使用startService启动service
    public void start(View view) {
        intent = new Intent(this, MyService.class);
        //传出值
        intent.putExtra("testValue", "testData");
        startService(intent);
    }
   //使用stopService停止service
    public void stop(View view) {
        stopService(intent);
    }

MyService.java

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        data=intent.getStringExtra("testValue");
        Log.e(TAG,"传入值     "+intent.getStringExtra("testValue"));
        return super.onStartCommand(intent, flags, startId);
    }

输出结果   传入值 11    testData

2. 使用Binder进行传值与回调

MainActivity.java

    MyService.DebugBinder binder;
    public void start(View view) {
        binder.getValue();
        Log.e("===========", "getValue     " + binder.getValue());
    }
    
    public void stop(View view) {
        binder.setValue("123456789");
    }

    ServiceConnection connection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            //连接建立后IBinder 转型为MyService.DebugBinder
            binder = (MyService.DebugBinder) service;
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {

        }
    };
   //使用bindService 绑定Service
  public   void connect() {
        Intent intent = new Intent(MainActivity.this, MyService.class);
        bindService(intent, connection, BIND_AUTO_CREATE);
    }
   //使用unbindService解绑Service
   public void disConnect(View view) {
     unbindService(connection);
    }


MyService.java

    @Override
    public IBinder onBind(Intent intent) {
       data=intent.getStringExtra("testValue");
       return new DebugBinder();
    }

    //DebugBinder  继承Binder  开发者可在其中定义自己需要的各种方法
    public class  DebugBinder extends Binder {
        String  getValue(){
            return "value";
        }
        void setValue(String value){
            Log.e("===========","setValue     "+value);
        }
    }


输出值  getValue     value
        setValue     123456789

3.使用EventBus等事件总线

    // 引入eventbus包
    implementation 'org.greenrobot:eventbus:3.2.0'

MainActivity.java

    @Override
    protected void onStart() {
        super.onStart();
        if (!EventBus.getDefault().isRegistered(this)){
            EventBus.getDefault().register(this);
        }

    }

    @Override
    protected void onStop() {
        super.onStop();
        if (EventBus.getDefault().isRegistered(this)){
            EventBus.getDefault().unregister(this);
        }
    }

    //需添加 @Subscribe 注解 方法类型为public 方法有且仅能有一个参数
    @Subscribe (threadMode = ThreadMode.MAIN)
    public void event(String  string){
        Log.e("===========", "event     " + string);
    } 

MyService.java

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        data=intent.getStringExtra("testValue");
        Log.e(TAG,"传入值     "+intent.getStringExtra("testValue"));
        EventBus.getDefault().post("onStartCommand");
        return super.onStartCommand(intent, flags, startId);
    }

输出值   event     onStartCommand

4. 使用广播 推荐LocalBroadcastManager 本地广播 效率快安全性高
5. AIDL 一般在跨进程通信时使用