android学习笔记(10)service初步

淡淡的烟草味﹌ 2022-08-04 14:41 176阅读 0赞

前面学习了activity,service与它不同的地方是service可以后台运行,而activity不能.

**一,service与thread**  
当后台运行不需要用户交互时用service如后台下载;当后台老板运行的程序需要用户至上交互时用thread如音乐播放.  
**二,启动方式**  
可以通过activity来启动  
1,startService() 调用者和服务之间没有联系,即使调用 者退出了,服务仍运行.  
(1)创建一个服务类.  
点New Java Class图标创建一个类,在Superclass栏点Browse搜索service-android.app确定.  
(2)复写方法:onStartCommand() onBind() onCreate() onDestroy()  
在代码中右键-->Source-->Override Implemet Methods然后勾选要复写的方法  
(3)在manifest文件中声明服务:

(4)过程:onCreate()-->startService()-->onDestory()

2,bindService() 调用者和服务绑在一起,调用者一旦退出,服务也就终止.  
过程:onCreate-->onBind()-->onUnbind()-->onDestory()  
**三,源码:**  
activity\_main.xml:

MainActivity.java:

package com.example1.servicedemo;
    
    import org.apache.commons.logging.Log;
    
    import android.net.sip.SipAudioCall.Listener;
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.view.Menu;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    
    public class MainActivity extends Activity {
    	private Button btnButton;
    	private Button btnButton2;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            btnButton = (Button)findViewById(R.id.btnservicestart);
            btnButton2 = (Button)findViewById(R.id.btnservicestop);
            btnButton.setOnClickListener(listener);
            btnButton2.setOnClickListener(listener);
        }
    private OnClickListener listener = new OnClickListener() {
    	
    	@Override
    	public void onClick(View v) {
    		switch (v.getId()) {
    		case R.id.btnservicestart:
    			Intent intent = new Intent(MainActivity.this,ExamppleService.class);
    			startService(intent);
    			break;
    		case R.id.btnservicestop:
    			Intent intent2 = new Intent(MainActivity.this,ExamppleService.class);
    			startService(intent2);
    			break;
    		default:
    			break;
    		}
    		
    	}
    };
        
    }

ExamppleService.java:

package com.example1.servicedemo;
    
    import org.apache.commons.logging.Log;
    
    import android.app.Service;
    import android.content.Intent;
    import android.os.IBinder;
    import android.util.LogPrinter;
    
    public class ExamppleService extends Service {
    private static final String tag = "ExamppleService";
    	@Override
    	
    	public IBinder onBind(Intent arg0) {
    		
    		return null;
    	}
    
    	@Override
    	public void onCreate() {
    	Log.i(tag,"ExamppleService-->onCreate");
    		super.onCreate();
    	}
    
    	@Override
    	public void onDestroy() {
    		Log.i(tag,"ExamppleService-->onDestroy");
    		super.onDestroy();
    	}
    
    }

在manifest文件中声明服务:  
<service android:name=".Service"/>  
运行后可以看到相应的日志输出,在我这个版本中Log.i();显示有错,建议是rename但没用,求教.