IPC—Messenger

1.Messenger进程间通信时，bundle有Parcelable对象解析数据的时候，需要调用bundle.setClassLoader方法，否则可能出现类型转换异常，因为bundle在调用getXXX解析数据的时候，调用Parcelable的readParcelable方法，readParcelableCreator会判断传入的ClassLoader是否为空，为空是使用的是Parcel的ClassLoader，用来加载我们自定义的类就会报错。

示例：

客户端代码：

public class ClientActivity extends AppCompatActivity implements View.OnClickListener {
    private static final String TAG = "ClientActivity";
    @BindView(R.id.send)
    Button send;
    private Messenger sendMessager;
    private Intent intent;

    private Messenger getMessenger = new Messenger(new Handler() {
        @Override
        public void handleMessage(Message msg) {
            Bundle bundle = msg.getData();
            bundle.setClassLoader(getClass().getClassLoader());//防止出现无法识别object的异常
            Log.d(TAG, "收到服务端消息: " + bundle.getString("rp"));
        }
    });

    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            sendMessager = new Messenger(service);
            Message message = Message.obtain(null, 0);
            Bundle bundle = new Bundle();
            Data data = new Data();
            data.setAddress("天安门");
            data.setName("张三");
            data.setBankCard("6221889292992922");
            data.setBankOrg("中国农业银行");
            data.setEmail("1818181919@qq.com");
            data.setHeight(1.82);
            data.setIdCard("828992988889999X");
            data.setNation("汉");
            data.setOld(38);
            data.setPhone("18929929922");
            data.setQqNum("982892992");
            data.setSex("男");
            data.setWeight(148.2);
            bundle.putParcelable("data", data);
            message.setData(bundle);
            message.replyTo = getMessenger;//带上客户端监听
            try {
                sendMessager.send(message);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName name) {

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_client);
        ButterKnife.bind(this);
        intent = new Intent(this, ServerService.class);
        send.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        Log.d(TAG, "onClick: 准备发送");
        try {
            unbindService(serviceConnection);
        } catch (Exception e) {
            Log.e(TAG, e.getMessage());
        }
        bindService(intent, serviceConnection, Context.BIND_AUTO_CREATE);
    }

    @Override
    protected void onDestroy() {
        unbindService(serviceConnection);
        super.onDestroy();
    }
}

服务端代码：

public class ServerService extends Service {
    private static final String TAG = "ServerService";
    private Messenger messenger = new Messenger(new MsgHandler());

    private class MsgHandler extends Handler{
        @Override
        public void handleMessage(Message msg) {
            Bundle bundle = msg.getData();
            bundle.setClassLoader(getClass().getClassLoader());
            Data data = bundle.getParcelable("data");
            Log.d(TAG, "来自客户端的消息: "+data.toString());
            Messenger client = msg.replyTo;
            Message message = Message.obtain(null,1);
            Bundle bundle1=new Bundle();
            bundle1.putString("rp","收到了！");
            message.setData(bundle1);
            try {
                client.send(message);
            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }
    }

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

AndroidManifest声明：

<activity android:name=".process_communication.messager.ClientActivity" />
<service
     android:name=".process_communication.messager.ServerService"
     android:enabled="true"
     android:exported="true"
     android:process=":server" />