Android——Activity与Service通信

Activity和Service之间有个常用的通信方式，通过Binder来进行通信，这里举一个进度条更新的例子来解释一下

先看一下整体的图，整个的构造大概就是这样的，Activity启动一个service，后台进行service的更新，并将数据传递给前台，前台控制数据的下载和暂停

1. xml文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.ld.servicetest.MainActivity">


    <ProgressBar
        android:id="@+id/pb"
        style="@android:style/Widget.ProgressBar.Horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="begin"/>

    <Button
        android:id="@+id/stop"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="stop"/>

</LinearLayout>

一个进度条，两个按钮

2. MyService

package com.example.ld.servicetest;

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;

public class MyService extends Service {

    private int progress = 0;
    private boolean stop = false;

    public int getProgress(){
        return progress;
    }

    public void setStop(boolean temp){
        stop = temp;
    }

    public boolean getStop(){
        return stop;
    }

    //进度条更新操作
    public void startDownLoad(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                while(progress<100 && !stop){
                    progress += 5;
                    try{
                        Thread.sleep(1000);
                    }catch(InterruptedException e){
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

    public MyService() {
    }


    //为了返回Service本身的操作
    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        return new MyBinder();
    }

    public class MyBinder extends Binder{
        public MyService getService(){
            return MyService.this;
        }
    }

}

3. MainActivity

package com.example.ld.servicetest;

import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;

public class MainActivity extends AppCompatActivity {

    private int progress = 0;
    private MyService mService;
    private ProgressBar mProgressBar;
    private Button begin, stop;

    //跟新UI的handler
    private Handler mHandler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
            Bundle mBundle = msg.getData();
            int progress = mBundle.getInt("progress");
            mProgressBar.setProgress(progress);
        }
    };

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

        //启动后台服务
        Intent intent = new Intent(MainActivity.this,MyService.class);
        bindService(intent,conn, Context.BIND_AUTO_CREATE);

        mProgressBar = (ProgressBar)findViewById(R.id.pb);
        begin = (Button)findViewById(R.id.btn);
        stop = (Button)findViewById(R.id.stop);
        begin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mService.setStop(false);
                mService.startDownLoad();
                updateProgress();
            }
        });
        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mService.setStop(true);
            }
        });
    }

    public void updateProgress(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                while(progress<100 && !mService.getStop()){
                    progress = mService.getProgress();
                    Message msg = new Message();
                    Bundle temp = new Bundle();
                    temp.putInt("progress",progress);
                    msg.what = 1;
                    msg.setData(temp);
                    mHandler.sendMessage(msg);
                }
            }
        }).start();
    }

    //获取mService实例
    ServiceConnection conn = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
            mService = ((MyService.MyBinder)iBinder).getService();
        }

        @Override
        public void onServiceDisconnected(ComponentName componentName) {


        }
    };

    //关掉服务并退出
    protected void onDestroy(){
        unbindService(conn);
        super.onDestroy();
    }

}

整个代码比较简单，注释也比较清晰，不再赘述。本人博客里也介绍过handler的使用和Service的启动，不明白的可以看看另外两篇文章

还有其他的通信方式，由于还没有代码实现，后期会持续更新。。。。。