如果把Activity比喻为前台程序，那么Service就是后台程序，Service的整个生命周期都只会在后台执行。Service跟 Activity一样也由Intent调用。在工程里想要添加一个Service，先新建继承Service的类，然后到 AndroidManifest.xml -> Application ->Application Nodes中的Service标签中添加。
Service要由Activity通过startService 或者 bindService来启动，Intent负责传递参数。
startService与bindService都可以启动Service，那么它们之间有什么区别呢?它们两者的区别就是使Service的周期改变。由 startService启动的Service必须要有stopService来结束Service，不调用stopService则会造成 Activity结束了而Service还运行着。bindService启动的Service可以由unbindService来结束，也可以在 Activity结束之后(onDestroy)自动结束。
程序运行截图
[代码] main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"android:id="@+id/btnStartMyService"
android:text="StartMyService"></Button>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"android:id="@+id/btnStopMyService"
android:text="StopMyService"></Button>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"android:id="@+id/btnBindMyService"
android:text="BindMyService"></Button>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content"android:id="@+id/btnUnbindMyService"
android:text="UnbindMyService"></Button>
<Button android:layout_width="wrap_content"
android:layout_height="wrap_content" android:id="@+id/btnExit"
android:text="退出程序"></Button>
</LinearLayout>
[代码] TestService.java
package com.testService;
import android.app.Activity;
import android.app.Service;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class TestService extends Activity {
Button btnStartMyService,btnStopMyService,btnBindMyService,btnUnbindMyService,btnExit;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
btnStartMyService=(Button)this.findViewById(R.id.btnStartMyService);
btnStartMyService.setOnClickListener(new ClickEvent());
btnStopMyService=(Button)this.findViewById(R.id.btnStopMyService);
btnStopMyService.setOnClickListener(new ClickEvent());
btnBindMyService=(Button)this.findViewById(R.id.btnBindMyService);
btnBindMyService.setOnClickListener(new ClickEvent());
btnUnbindMyService=(Button)this.findViewById(R.id.btnUnbindMyService);
btnUnbindMyService.setOnClickListener(new ClickEvent());
btnExit=(Button)this.findViewById(R.id.btnExit);
btnExit.setOnClickListener(new ClickEvent());
}
@Override
public void onDestroy()
{
super.onDestroy();
Log.e("Activity","onDestroy");
}
private ServiceConnection _connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName arg0, IBinder arg1) {
// TODO Auto-generated method stub
}
@Override
public void onServiceDisconnected(ComponentName name) {
// TODO Auto-generated method stub
}
};
class ClickEvent implements View.OnClickListener{
@Override
public void onClick(View v) {
Intent intent=newIntent(testService.this,MyService.class);
if(v==btnStartMyService){
testService.this.startService(intent);
}
else if(v==btnStopMyService){
testService.this.stopService(intent);
}
else if(v==btnBindMyService){
testService.this.bindService(intent, _connection, Service.BIND_AUTO_CREATE);
}
else if(v==btnUnbindMyService){
if(MyService.ServiceState=="onBind")//Service绑定了之后才能解绑
testService.this.unbindService(_connection);
}
else if(v==btnExit)
{
testService.this.finish();
}
}
}
}
[代码] MyService.java
package com.testService;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
public class MyService extends Service {
static public String ServiceState="";
@Override
public IBinder onBind(Intent arg0) {
Log.e("Service", "onBind");
ServiceState="onBind";
return null;
}
@Override
public boolean onUnbind(Intent intent){
super.onUnbind(intent);
Log.e("Service", "onUnbind");
ServiceState="onUnbind";
return false;
}
@Override
public void onCreate(){
super.onCreate();
Log.e("Service", "onCreate");
ServiceState="onCreate";
}
@Override
public void onDestroy(){
super.onDestroy();
Log.e("Service", "onDestroy");
ServiceState="onDestroy";
}
@Override
public void onStart(Intent intent,int startid){
super.onStart(intent, startid);
Log.e("Service", "onStart");
ServiceState="onStart";
}
}
