安卓跨进程通信：Messenger、AIDL远程Service 使用

Messenger

服务端

创建Service：

public class MessengerService extends Service {
    private static final int MSG_SUM = 0x110;
    private Messenger messenger = new Messenger(new Handler() {
        @Override
        public void handleMessage(@NonNull Message msg) {
            Message message = Message.obtain(msg);
            switch (msg.what) {
                case MSG_SUM:
                    message.what = MSG_SUM;
                    try {
                        Thread.sleep(2000);
                        message.arg2 = msg.arg1 + msg.arg2;
                        msg.replyTo.send(message);
                    } catch (InterruptedException | RemoteException e) {
                        e.printStackTrace();
                    }
                    break;
                default:
                    break;
            }
            super.handleMessage(msg);
        }
    });

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

在Service中创建Messenger实例，通过Message消息机制进行操作，Service的onBind中返回messenger实例的Binder对象。

注册service：

<service
    android:name=".MessengerService"
    android:enabled="true"
    android:exported="true">
    <intent-filter>
        <action android:name="com.example.messengerserver" />
    </intent-filter>
</service>

此处action值随意设置，后续和intent的action匹配即可。

客户端

public class MainActivity extends AppCompatActivity {
    private static final int MSG_SUM = 0x110;

    private Button button;
    private LinearLayout layout;
    private TextView mTvState;

    private Messenger mService;
    private boolean isConn;

    private Messenger mMessenger = new Messenger(new Handler() {
        @Override
        public void handleMessage(@NonNull Message msg) {
            switch (msg.what) {
                case MSG_SUM:
                    TextView tv = (TextView) layout.findViewById(msg.arg1);
                    tv.setText(tv.getText() + "=>" + msg.arg2);
                    break;
            }
            super.handleMessage(msg);
        }
    });

    private ServiceConnection mConn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            mService = new Messenger(iBinder);
            isConn = true;
            mTvState.setText("conn");
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {
            mService = null;
            isConn = false;
            mTvState.setText("dis");
        }
    };

    private int mA;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Intent intent = new Intent();
//        intent.setAction("com.example.messengerserver");
        intent.setPackage("com.example.messengerserver");
        bindService(intent, mConn, BIND_AUTO_CREATE);

        mTvState = (TextView) findViewById(R.id.id_tv_callback);
        button = (Button) findViewById(R.id.id_btn_add);
        layout = (LinearLayout) findViewById(R.id.id_ll_container);

        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                try {
                    int a = mA++;
                    int b = (int) (Math.random() * 100);

                    //创建一个tv,添加到LinearLayout中
                    TextView tv = new TextView(MainActivity.this);
                    tv.setText(a + " + " + b + " = caculating ...");
                    tv.setId(a);
                    layout.addView(tv);

                    Message msg = Message.obtain(null, MSG_SUM, a, b);
                    msg.replyTo = mMessenger;
                    if (isConn) {
                        mService.send(msg);
                    }
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
        });
    }
}

注：
①intent设置：隐式必须声明package为service所在包名（而action不必声明，但若声明则必须和服务端设置的action相同，否则service绑定失败）
②ServiceConnection为连接、断开的回调方法
③流程：
a、客户端与服务端通过service绑定成功后，调用ServiceConnection回调方法，客户端依据返回的binder生成给服务端发送信息的messenger

mService = new Messenger(iBinder);

b、客户端创建message给服务端发送

Message msg = Message.obtain(null, MSG_SUM, a, b);
msg.replyTo = mMessenger;		//此处绑定客户端的Messenger，用于接收信息时触发此处的handleMessage
if (isConn) {
    mService.send(msg);
}

c、服务端接收信息进行数据处理并给在message绑定好的Messenger发送信息

message.arg2 = msg.arg1 + msg.arg2;
msg.replyTo.send(message);

发送回客户端后触发handleMessage

AIDL+远程Service

服务端

interface IPersonAidlInterface {
    /**
     * Demonstrates some basic types that you can use as parameters
     * and return values in AIDL.
     */
     void setName(String name);
     void setAge(int age);
     String getInfo();
    void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat,
            double aDouble, String aString);
}

创建aidl文件夹及包+aidl文件（包名需与java文件夹内包相同）
aidl文件创建后，makeProject再继续编写。

public class PersonService extends Service {
    public PersonService() {
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return new IPersonImpl();
    }

    public class IPersonImpl extends IPersonAidlInterface.Stub {
        private String name;
        private int age;

        @Override
        public void setName(String name) throws RemoteException {
            this.name = name;
            Log.i("server", name);
        }

        @Override
        public void setAge(int age) throws RemoteException {
            this.age = age;
        }

        @Override
        public String getInfo() throws RemoteException {
            return "My name is "+name+", age is "+age+"!";
        }

        @Override
        public void basicTypes(int anInt, long aLong, boolean aBoolean, float aFloat, double aDouble, String aString) throws RemoteException {

        }
    }
}

创建aidl.stub子类，重写方法逻辑，在Service的onbind返回stub实例。

声明service：

<service android:name=".PersonService"
    android:enabled="true"
    android:exported="true"
    android:process=":remote">
    <intent-filter>
        <action android:name="com.example.aidlserver" />
    </intent-filter>
</service>

此处注意点同messenger

客户端

将服务端创建的aidl文件夹复制到客户端中，再makeProject

public class MainActivity extends AppCompatActivity {
    private IPersonAidlInterface iPersonAidlInterface;
    TextView textView;
    private ServiceConnection serviceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            iPersonAidlInterface = IPersonAidlInterface.Stub.asInterface(iBinder);
            try {
                iPersonAidlInterface.setName("123");
                textView.setText(iPersonAidlInterface.getInfo());

            } catch (RemoteException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {

        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView = findViewById(R.id.text);
        Intent intent = new Intent();
//        intent.setAction("com.example.aidlserver");
        intent.setPackage("com.example.aidlserver");
        bindService(intent, serviceConnection, BIND_AUTO_CREATE);
    }

}

注：
①在ServiceConnection中主要执行iPersonAidlInterface = IPersonAidlInterface.Stub.asInterface(iBinder);，后续通过iPersonAidlInterface即可调用服务端方法
②服务绑定注意点与方法和Messenger相同

对比

Messenger主要通过Message消息机制进行通信，省去了AIDL接口的编写与实现
两者都需要通过Service进行服务端、客户端关系绑定，绑定后再实现通信。