Android Service

一、简介

Service是Android的四大组件之一，它可以使应用程序保持在后台运行，它非常适合去执行那些不需要和用户交互而且长期运行的任务，服务的运行不依赖于任何用户界面，即使程序被切换到后台，或者用户打开了另外一个应用程序，服务仍然能够保持正常运行。

二、创建服务

新建一个类，继承Service

import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;

public class MyService extends Service {

    public MyService(){
        
    }

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

在配置文件中注册

        <service
            android:name=".MyService"
            android:enabled="true"
            android:exported="true" />

三、独立的服务(生命周期和进程一致)

启动服务

        Intent intent = new Intent(this,MyService.class);
        startService(intent);

关闭服务

        Intent intent = new Intent(this,MyService.class);
        stopService(intent);

        stopSelf(); //服务内部调用

四、活动与服务通信(生命周期和活动一致)

创建与活动通信的服务

import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.support.annotation.Nullable;

public class MyService extends Service {

    private MyBinder mBinder = new MyBinder();

    public MyService(){

    }

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

    class MyBinder extends Binder{
        public void start(){}
        public int getProgress(){return 0;}
        public void end(){}
    }
}

Activity中的实现

    private MyService.MyBinder mBinder;
    private ServiceConnection mServiceConnection = new ServiceConnection() {
        @Override
        public void onServiceConnected(ComponentName name, IBinder service) {
            mBinder = (MyService.MyBinder) service;
            mBinder.start(); //活动和服务通信
            mBinder.getProgress(); //活动和服务通信
        }

        @Override   
        public void onServiceDisconnected(ComponentName name) {
            mBinder.end(); //活动和服务通信
        }
    };

绑定服务

        Intent intent = new Intent(this,MyService.class);
        bindService(intent,mServiceConnection,BIND_AUTO_CREATE);

解绑服务

        unbindService(mServiceConnection);

五、前台服务

import android.app.Notification;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.v4.app.NotificationCompat;

public class MyService extends Service {

    public MyService(){
        Intent intent = new Intent(this,MainActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(this,0,intent,0);
        Notification notification =new NotificationCompat.Builder(this) 
                .setContentTitle("通知栏标题")
                .setContentText("通知栏内容")
                .setWhen(System.currentTimeMillis())
                .setSmallIcon(R.mipmap.ic_launcher)
                .setLargeIcon(BitmapFactory.decodeResource(getResources(),R.mipmap.ic_launcher))
                .setContentIntent(pendingIntent)
                .build();
        //启动前台服务
        startForeground(1,notification);  // 1是通知栏的id，每个通知的id都不一样
        //在通知栏显示通知
        //NotificationManager manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
        //manager.notify(1,notification); // 1是通知栏的id，每个通知的id都不一样
    }

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

六、自动停止的服务

import android.app.IntentService;
import android.content.Intent;
import android.support.annotation.Nullable;

public class MyIntentService extends IntentService {
    
    public MyIntentService(String name) {
        super(name);
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        //执行逻辑，完成后，会自动停止服务，用法和普通服务一样
    }
}