Android四大应用组件之Service篇

总结自Android四大应用组件之Service篇
Android四大应用组件之Activity篇https://www.jianshu.com/p/d22981a8ad0e
Android四大应用组件之Service篇https://www.jianshu.com/p/f7d57803b86e
Android四大应用组件之ContentProvider篇https://www.jianshu.com/p/5f783f3db22d
Android四大应用组件之BroadcastReceiver篇https://www.jianshu.com/p/e6283dec21c7

理论概述

Service是一个应用组件，它用来在后台完成一个时间跨度比较大的工作且没有关联任何界面

默认运行在主线程（UI线程）。耗时工作放在子线程中执行。
即使应用退出，服务也不会停止。

功能：访问网络、播放音乐、文件IO、大数据量的数据库操作

本地服务Local Service：Service对象与Service启动者在同一个进程
远程服务Remoe Service：Service对象与Service启动者不在同一个进程

启动与停止Service

方式一：一般启动
context.startService(Intent intent)
context.stopService(Intent intent)

2.png 1.png

Intent intent = new Intent(this,MyService.class);
startService(intent);
Log.d("TAG","启动");

Intent intent = new Intent(this,MyService.class);
stopService(intent);
Log.d("TAG","销毁");

//目前先省略其他生命周期方法
点击启动---》
MyService()
MyService onCreate()
点击销毁---》
MyService destroy()

方式二：绑定启动
context.bindService(Intent intent,ServiceConnection con)
context.unbindService(ServiceConnection con)

startService只负责启动并不绑定（产生连接）

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

if(conn == null){
  conn = new ServiceConnection(){
    @Override
    public void onServiceDisconnected(ConponentName name){
      Log.d("TAG","onServiceDisconnected");
    }
    @Override
    public void onServiceConnected(ConponentName   name,IBinder service){
      Log.d("TAG","onServiceConnected");
    }
  }
  bindService(intent,conn,Context.BIND_AUTO_CREATE);
  Log.d("TAG","bindService");
}else{
  Log.d("TAG","已经绑定");
}

if(conn!=null){
  unbindService(conn );
  conn=null;
  Log.d("TAG","unbindService");
}else{
  Log.d("TAG","还未绑定");
}

点击bind---》

    MyService()
    MyService onCreate()
    MyService onBind()
    MyService onServiceConnected

点击unbind---》

    unbindService
    MyService destroy()//最后一个client unbind后会自动onUnbind()-->onDestroy()

在Activity退出之前（onDestroy）要调用unbind,否则会泄漏

Service生命周期

3.png

1、startService()只有第一次会调用onCreate之后启动会直接走onStartcommand()
2、所有的Clients调用unBindService后，Service会调用onUnbind()-->onDestroy()!!

点击startService()--->

MyService  构造方法
MyService  onCreate()
MyService  onStartCommand()

再次点击startService()--->

 MyService onStartCommand()

点击stopService()--->

 MyService onDestroy()

2点击bindService(intent,conn)--->

 MyService 构造方法
 MyService onCreate()
 MyService onBind()
 onServiceConnected()

点击unbindService(conn)//当前只有1个相连--->

MyService onUnBind()
MyService onDestroy()

远程服务

4.png

另一个应用的服务端：

5.png

<service android:name="com.xxx1.MyRemoteService">
  <intent-filter>
    <action android:name="com.xxx1.MyRemoteService.Action">
  </intent-filter>
</service>

public class MyRemoteService extends Service{
  @Override
  public IBinder onBind(Intent intent){
    return new StudentService();
  }
    //处理Student相关的业务逻辑类
  class StudentServece extend IStudentService.Stub{
    @Override
    public student getStudentById(int id) throws RemoteException{
      return new Student(id,"TOM",10000);
    }
  }
}

服务端定义AIDL接口+Student类

服务端创建IStudentService.aidl(改名为aidl)

package....xxx1...;
import com.xxx1.Student;//必须导包

intenrface IStudentService{
  Student getStudentById(int id);
}

public class Student implements Parcelable{
  private int id;
  private  String name;
  private double price;
  public Student (int id,String name,double price){
    super();
    this.id=id;
    this.name=name;
    rhis.price = price;
  }
  ...//  get/set /toString 方法略
  // Parcelable方法
  @Override
  public void writeToParcel(Parcel dest,int flags){
    dest.wrteInt(id);
    dest.wrteString(name);
    dest.wrteDouble(price);
  }
  //
  public static final Parcelable.Creator<Student> CREATOR = new Parcelable.Creator<Student>(){
    //解包
   @Override
   public Student createFromParcel(Parcel source){
      //必须按照写的顺序读（先int 后string 、float）
      int id = source.readInt();
      String name=source.readString();
      double price = source.readDouble();
      return new Student(id,name,price);
    }
    //返回一个指定大小的对象容器
  @Override
   public Student[] newArray(int size){
      return new Student[size];
    }
 }
}

服务端创建Student.aidl

package com.xxx1...;
parcelable Student;

另一个应用的客户端：
绑定远程服务---》调用远程服务方法---》unbind

复制Student.java、IStudentService.aidl、Student.aidl而且包名不能改

6.png

ServiceConnection conn;
IStudentService studentService;

public void bindR(){
 Intent intent = new Intent("com.xxx1.MyRemoteService.Action");
 if(conn == null){
  conn = new ServiceConnection(){
   @Override
   public void onServiceDisconnected(ConponentName name){
    Log.d("TAG","onServiceDisconnected");
   }
   @Override
   public void onServiceConnected(ConponentName   name,IBinder service){
    Log.d("TAG","onServiceConnected");
    studentService=IStudentService.Stub.asInterface(service);
 
   }
  }
  bindService(intent,conn,Context.BIND_AUTO_CREATE);
  Log.d("TAG","bindService");
 }else{
  Log.d("TAG","已经绑定");
 }
}

public void useR(){
  if(studentService!=null){
      Student st = studentService.getStudentById(1);
  }
}

public void unbindR(){
 if(conn!=null){
   unbindService(conn);
   conn=null;
   studentService=null;
   Log.d("TAG","unbindService");
 }else{
  Log.d("TAG","还未绑定");
 }
}