Android Framework基础之基于Messenger的进程通行

参考使用 Messenger实现与独立进程的Service的双向通信
纯纯是自己学习，别看

AndroidManifest.xml

 <service
       android:name=".MyService"
       android:enabled="true"
       android:exported="true" >
       <intent-filter>
            <action android:name="com.example.handlemessage.MyService" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
</service>

MainActivity.java

package com.example.handlemessage;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.app.Service;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;


//what：整型的消息标识，用于标识本次消息的唯一编号。
//arg1：整型数，可存放消息的处理结果。
//arg2：整型数，可存放消息的处理代码。
//obj：Object类型，可存放返回消息的数据结构。
//replyTo：Messenger类型，回应信使，在跨进程通信中使用，多线程通信用不着

public class MainActivity extends AppCompatActivity {
    
    

    private String TAG = "jerry";
    private static final int MSG_SAY_HELLO = 1;
    private static final int MSG_REQUEST_MESSAGE = 2;
    private static final int MSG_RESULT_CODE = 3;
    private TextView mTextView;
    private Button mButton;
    private Button mButton1;
    private Messenger mService;

    private Handler handlerMyService = new Handler(Looper.getMainLooper()){
    
    
        @Override
        public void handleMessage(@NonNull Message msg) {
    
    
            switch(msg.what){
    
    
                case MSG_RESULT_CODE:
                    mTextView.setText("Myservice callbak");
                    Log.e(TAG,"result message");
                    break;
                default:
                    super.handleMessage(msg);
            }
        }
    };
    final Messenger mMessenger = new Messenger(handlerMyService);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mTextView = findViewById(R.id.textView);

        mButton = findViewById(R.id.button);
        mButton.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View view) {
    
    
                ServiceConnection conn = new ServiceConnection() {
    
    
                    @Override
                    public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
    
    
                        mService = new Messenger(iBinder);
                        Log.e(TAG, "binder success");
                        Message message = new Message();
                        message.replyTo = mMessenger;
                        message.what = MSG_REQUEST_MESSAGE;
                        try {
    
    
                            mService.send(message);
                        } catch (RemoteException e) {
    
    
                            e.printStackTrace();
                        }
                    }
                    @Override
                    public void onServiceDisconnected(ComponentName componentName) {
    
    
                        mService = null;
                    }
                };
                ComponentName cn = new ComponentName("com.example.handlemessage",
                        "com.example.handlemessage.MyService");
                Intent intent = new Intent();
                intent.setComponent(cn);
                bindService(intent, conn, Service.BIND_AUTO_CREATE);

            }
        });
        mButton1 = findViewById(R.id.button1);
        mButton1.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View view) {
    
    
                Message message = new Message();
                message.what = MSG_SAY_HELLO;
                try {
    
    
                    mService.send(message);
                } catch (RemoteException e) {
    
    
                    e.printStackTrace();
                }

            }
        });
    }

}

MyService.java

package com.example.handlemessage;

import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.util.Log;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;


//https://blog.csdn.net/u011459799/article/details/52012606?utm_source=itdadao&utm_medium=referral
public class MyService extends Service {
    
    
    private String TAG = "jerry";

    static final int MSG_SAY_HELLO = 1;
    static final int MSG_REQUEST_MESSAGE = 2;
    static final int MSG_RESULT_CODE = 3;
    private Messenger mRequestMessenger = null;

    private Handler handler = new Handler(Looper.getMainLooper()){
    
    
        @Override
        public void handleMessage(@NonNull Message msg) {
    
    
            switch(msg.what){
    
    
                case MSG_SAY_HELLO:
                    Log.e(TAG, "hello message");
                    Message message = new Message();
                    message.what = MSG_RESULT_CODE;
                    try {
    
    
                        Thread.sleep(1000);
                        mRequestMessenger.send(message);
                    } catch (InterruptedException | RemoteException e) {
    
    
                        e.printStackTrace();
                    }
                    break;
                case MSG_REQUEST_MESSAGE:
                    Log.e(TAG, "request message");
                    mRequestMessenger = msg.replyTo;
                    break;
                default:
                    super.handleMessage(msg);
            }
        }
    };

    final Messenger  mMessenger = new Messenger (handler);

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