android学习笔记(13) intent Services多线程初步

﹏ヽ暗。殇╰゛Y 2022-08-04 14:54 209阅读 0赞

**IntentService是Service类的子类,用来处理异步请求,客户端通过startService(intent)方法传递请求给IntentService,IntentService通过worher thread处理每个Intent对象,执行完所有工作后自动停止Service.**

**IntentService执行如下操作:  
\*创建一个与应用程序线程分开的worker thread 用来处理所有通过学习onstartcommand()传递过来的Intent请求  
\*创建一个work queue,一次只传递一个intent到onHandleIntent()方法中,从而不用担心多线程带来的问题  
\*当处理完所有请求后自动停止服务,而不需要我们自己调用stopSelf()方法.  
\*默认实现了onBind()方法,返回值为null  
\*默认实现了onStartCommand()方法,这个方法将会把我们的intent放到work queue中,然后在onHandleIntent()中执行.  
:  
写构造方法**

**复写onHandleIntent()方法**

**源码对一般的多线程服务和intent service多线程对比:**

**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 {
    	protected static final String TAG = "MainActivity";
    	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.btnstartnormalservice);
            btnButton2 = (Button)findViewById(R.id.btnstartintentservice);
            btnButton.setOnClickListener(listener);
            btnButton2.setOnClickListener(listener);
        }
    private OnClickListener listener = new OnClickListener() {
    	
    	@Override
    	public void onClick(View v) {
    		switch (v.getId()) {
    		case R.id.btnstartnormalservice:
    			Intent intent = new Intent(MainActivity.this,ExampleService.class);
    			Log.i(TAG,"主线程ID："+Thread.currentThread().getId());//输出当前线程ID
    			startService(intent);
    			break;
    		case R.id.btnstartintentservice:
    			Intent intent2 = new Intent(MainActivity.this,ExampleIntentService.class);
    			Log.i(TAG,"主线程ID："+Thread.currentThread().getId());//输出当前线程ID
    			startService(intent);
    			break;
    		default:
    			break;
    		}
    		
    	}
    };
        
    }

**ExampleIntentService.java**

package com.example1.servicedemo;
    
    import android.app.IntentService;
    import android.content.Intent;
    
    public class ExampleIntentService extends IntentService {
    
    	private static final String tag = "ExampleIntentService";
    
    	public ExampleIntentService(String name) {
    		super("ExampleIntentService");
    		
    	}
    
    	@Override
    	protected void onHandleIntent(Intent arg0) {
    		try {
    			android.util.Log.i(tag,"Exampleservice线程ID："+Thread.currentThread().getId());
    			android.util.Log.i(tag,"文件下载...");
    			Thread.sleep(2000);            
    		} catch (InterruptedException e) {
    			
    			e.printStackTrace();
    		}
    
    	}
    
    }

**记得在XML中声明服务!!： <service android:name=".ExampleIntentService"/>**

**结果:**

**多次点击startnormalservice按键:**

**主线程ID：1**

**Exampleservice线程ID：9**

文件下载...

主线程ID：1

Exampleservice线程ID：10

文件下载...

主线程ID：1

Exampleservice线程ID：11

文件下载...