IPC进程间通信方式

提到进程间通信首先想到就是aidl方式，本文除了介绍该方式外还会介绍通过Messenger实现，看到Messenger很容易想到Message(Messenger核心是通过Message和Handler进程通信)，下面分别介绍这两种方式

一、Messenger方式

1、服务端创建Handler，来处理客户端发来的消息

2、通过Handler实例创建Messenger实例

3、在onBind(Intent intent)方法中返回messenger获得的IBinder实例

4、客户端绑定服务回调onServiceConnected方法通过IBinder获得服务端的Messenger实例

5、客户端通过messenger发送消息到服务端

（1）服务端主要代码：

public class MyService extends Service {

    private Messenger messenger;
    private Handler mHandler = new Handler() {
        @Override public void handleMessage(Message msg) {
            super.handleMessage(msg);
            Log.i("aa", "**收到消息");
            Toast.makeText(MyService.this, "收到消息！", Toast.LENGTH_SHORT).show();
        }
    };


    public MyService() {

    }

    @Override
    public IBinder onBind(Intent intent) {
        messenger = new Messenger(mHandler);
        return messenger.getBinder();
    }

}

（2）客户端主要代码：

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    private Messenger messenger;
    private ServiceConnection connection = new ServiceConnection() {
        @Override public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            messenger = new Messenger(iBinder);
        }


        @Override public void onServiceDisconnected(ComponentName componentName) {
            messenger = null;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button bt1 = (Button)findViewById(R.id.act_bt1);
        Button bt2 = (Button)findViewById(R.id.act_bt2);
        bt1.setOnClickListener(this);
        bt2.setOnClickListener(this);
    }


    @Override public void onClick(View view) {
        switch (view.getId()){
            case R.id.act_bt1:
                Intent intent = new Intent();
                intent.setAction("com.huizhong.service");
                intent.setPackage("com.huizhong.onedemo");//不设置包名会报异常
                bindService(intent, connection, Context.BIND_AUTO_CREATE);
                break;
            case R.id.act_bt2:
                if (messenger == null){
                    Toast.makeText(MainActivity.this, "请先绑定服务", Toast.LENGTH_SHORT).show();
                }else {
                    try {
                        Message message = new Message();
                        messenger.send(message);
                    } catch (RemoteException e) {
                        e.printStackTrace();
                    }
                }
                break;
        }
    }
}