Android Service详解

首先介绍一下Service的两种启动方式，

第一种是通过是startService方法启动服务，接受一个Inten的参数，首先调用service的onCreage犯法，再调用onStartCommond方法，与Activity类似

第二种是通过 bindService方法启动服务，如果服务未启动，首先会执行onCreate方法，否则只执行onStartCommond方法，在客户端调用bindService方法，服务类的onBind方法会被执行，此时该方法必须返回一个IBinder类，否则客户端的onServiceConnection因为没有参数而不会执行，当客户端的onServiceConnection执行了以后，服务类才与客户端类进行了成功的绑定，通过该binder类，客户端获得服务器的相关执行结果

启动的服务业可以与其进行绑定，绑定就是客户端与服务类共存亡。

package com.example.huanghanqing.testservice;

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

public class MainActivity extends Activity implements View.OnClickListener,ServiceConnection {

Button btnStartService,btnStopService,btnBindService,btnUnbindService,btnGetCurrentNum;
Intent i;
private int num;
MyService myService;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btnStartService = (Button)findViewById(R.id.btnStartService);
btnStopService = (Button)findViewById(R.id.btnStopService);
btnBindService = (Button)findViewById(R.id.btnBindService);
btnUnbindService = (Button)findViewById(R.id.btnUnbindService);
btnGetCurrentNum = (Button)findViewById(R.id.getCurrentNum);

i = new Intent(this,MyService.class);
btnStartService.setOnClickListener(this);
btnStopService.setOnClickListener(this);
btnBindService.setOnClickListener(this);
btnUnbindService.setOnClickListener(this);
btnGetCurrentNum.setOnClickListener(this);
}

@Override
public void onClick(View view) {
switch (view.getId()){
case R.id.btnStartService:
startService(i);//start service, and the service will not stop until onDesory is called
break;
case R.id.btnStopService:
stopService(i);//service will stoped
break;
case R.id.btnBindService:
bindService(i,this, Context.BIND_AUTO_CREATE);
break;
case R.id.btnUnbindService:
unbindService(this);
break;
case R.id.getCurrentNum:
System.out.println("当前服务的数字是"+myService.getCurrentNum());
}
}

@Override
public void onServiceConnected(ComponentName name, IBinder binder) {
System.out.println("onServiceConnected");
myService = ((MyService.MyBinder)binder).getService();
}

@Override
public void onServiceDisconnected(ComponentName name) {
System.out.println("onServiceDisConnection");//thi
4000
s method will called when the APP crashed
}
}

package com.example.huanghanqing.testservice;
import android.app.Service;

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

import java.util.Timer;
import java.util.TimerTask;

/**
* Created by huanghanqing on 2016/2/22.
*/
public class MyService extends Service {

private Timer timer = null;
private TimerTask timerTask = null;
private int i = 0;

@Nullable
@Override
public IBinder onBind(Intent intent) {

System.out.println("onBind");
return myBinder;
}
MyBinder myBinder = new MyBinder();
public class MyBinder extends Binder{
public MyService getService(){
return MyService.this;
}
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
System.out.println("onStartCommand");
return super.onStartCommand(intent, flags, startId);
}

@Override
public void onCreate() {
super.onCreate();
System.out.println("onCreate");
startTimer();
}

@Override
public void onDestroy() {
super.onDestroy();
System.out.println("onDestory");
stopTimer();
}

public  void startTimer(){
if (timer == null) {
timer = new Timer();
timerTask = new TimerTask() {
@Override
public void run() {
i++;
System.out.println(i);
}
};
timer.schedule(timerTask,1000,1000);
}
}

public void stopTimer(){
timer.cancel();;
timerTask.cancel();
}

public int getCurrentNum(){
return i;
}
}