Service的使用

首先说一下Service（服务）是什么，服务是Android的四大组件，运行在后台的没有界面的Activity,后台是不依赖UI就可以独立存在的，服务一般在内存不够用的情况下才会被杀死，不然只能手动关闭，如果你发现你的应用很耗电，看看后台Service多不多，关掉一些没有用的Service.

给大家贴上简单代码，明天给大家上传一个多线程上传断电续传的demo

package com.xiaojie.com.xiaojie.service;

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

/**
* 创建Service服务
* Created by Administrator on 2015/10/20.
*/
public class DownloadService extends Service {

public static final String tag = "DownloadService";
public MyBinder binder = new MyBinder();

@Override
public void onCreate() {
super.onCreate();
Log.e(tag, "onCreate()");
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.e(tag, "onStartCommand()");

new Thread(){
@Override
public void run() {
//开始后台执行任务
}
}.start();
return super.onStartCommand(intent, flags, startId);
}

@Override
public IBinder onBind(Intent intent) {

return binder;
}

@Override
public void onDestroy() {
super.onDestroy();
Log.e(tag, "onDestroy()");
}

public class MyBinder extends Binder {

public void startDownLoad() {
Log.e(tag, "downLoad()");
new Thread(){
@Override
public void run() {
//开始后台执行任务
}
}.start();
}
}
}

package com.xiaojie.com.xiaojie.ui;

import android.app.Activity;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.Button;

import com.xiaojie.com.xiaojie.R;
import com.xiaojie.com.xiaojie.service.DownloadService;

/**
* Created by Administrator on 2015/10/20.
*/
public class ServiceActivity extends Activity implements View.OnClickListener {
private Button bt_start_server;
private Button bt_stop_server;
private Button bt_bind_server;
private Button bt_unbind_server;
private DownloadService.MyBinder binder;
ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName componentName, IBinder iBinder) {
binder = (DownloadService.MyBinder) iBinder;
binder.startDownLoad();
}

@Override
public void onServiceDisconnected(ComponentName componentName) {

}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.atv_service);
bt_start_server = (Button) findViewById(R.id.bt_start_server);
bt_stop_server = (Button) findViewById(R.id.bt_stop_server);
bt_bind_server = (Button) findViewById(R.id.bt_bind_server);
bt_unbind_server = (Button) findViewById(R.id.bt_unbind_server);

bt_bind_server.setOnClickListener(this);
bt_stop_server.setOnClickListener(this);
bt_start_server.setOnClickListener(this);
bt_unbind_server.setOnClickListener(this);

}

@Override
public void onClick(View view) {
Intent intent = null;
switch (view.getId()) {
case R.id.bt_start_server:
intent = new Intent(ServiceActivity.this, DownloadService.class);
startService(intent);
break;
case R.id.bt_stop_server:
intent = new Intent(ServiceActivity.this, DownloadService.class);
stopService(intent);
break;
case R.id.bt_bind_server:
intent = new Intent(ServiceActivity.this, DownloadService.class);
bindService(intent, serviceConnection, BIND_AUTO_CREATE);
break;
case R.id.bt_unbind_server:
unbindService(serviceConnection);
break;
}
}
}

 
大家可以运行看下效果。多点点

大家可以发现，Service在第一次启动时会先执行onCreate,然后执行onStartCommand方法,之后添加再次调用只会执行onStartCommand方法。

启动服务分为两种方式，一种是startServer,一种是bindServer.

当一个Service被startServer后，只能被StopServer,服务被startServer后，并且还可以被bind,

bindServer方便与Activity进行交互，把Server的binder对象控制权交给Activity.

如果是startServer只能在onstartCommand方法中通过Handler然后发送广播在Activity中接收

Server分为两种，一种是本地服务，和远程服务