Android Service通过Handler与Activity交互

最新推荐文章于 2021-05-27 09:48:25 发布

原创最新推荐文章于 2021-05-27 09:48:25 发布 · 置顶 · 747 阅读

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本文介绍了一个Android应用中Activity与Service通过Messenger进行通信的例子。主要内容包括：MainActivity中定义Handler来接收消息，并启动HandlerService；HandlerService接收到消息后，通过Messenger回调主线程的Handler，实现跨组件的消息传递。

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activity代码

package com.app.yr.jnidemo;

import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.Messenger;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.btnTest).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                handler.post(new Runnable() {
                    @Override
                    public void run() {
                        Intent intent = new Intent(MainActivity.this, HandlerService.class);
                        intent.putExtra("messenger", new Messenger(handler));
                        startService(intent);
                    }
                });
            }
        });
    }

    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 1:
                    ((TextView) findViewById(R.id.tvHandler)).setText("this is a message from service");
                    break;
            }
        }
    };

}

service代码

package com.app.yr.jnidemo;

import android.app.Service;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.Messenger;
import android.os.RemoteException;
import android.support.annotation.Nullable;


public class HandlerService extends Service {
    private Messenger mMessenger;
    private Handler mHandler = new Handler();

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

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (mMessenger == null) {
            mMessenger = (Messenger) intent.getExtras().get("messenger");
        }
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                Message message = Message.obtain();
                message.what = 1;
                try {
                    mMessenger.send(message);
                } catch (RemoteException e) {
                    e.printStackTrace();
                }
            }
        }, 10000);
        return super.onStartCommand(intent, flags, startId);
    }
}