Question

我正在下载一组图片。所以我有一个带静态方法的静态类，我用它来启动新的主线程。在主线程中，我创建了新的工作线程，为我下载图像，这在主线程的run方法中发生。在工作线程完成其任务后，它将被删除。

经过一段时间后，我正在导航到我的应用程序中的其他页面，该页面调用相同的静态方法，再次调用相同的进程。我将请求添加到此主线程类中的向量队列，但是run方法已经完成。

如何让它再次运行？

这是接近线程的正确方法吗？

静态类的静态方法

public class ImageLoader {
    private static Vector requestQueue = new Vector();  
    static ImageDownloader  mThread ;   

    public static void loadImage(String url,ImageDownloadListener _listner){         
         CustomWorkerThread thread = new CustomWorkerThread(url, _listner);
         if(mThread==null){
             mThread = new ImageDownloader();
             if(!mThread.isAlive()){
                 mThread.start();
               }

        }
         ImageDownloader.loadImageThread(thread);
    }   
    public static void closeThreads(){
        ImageDownloader.stopAllThreads();
    }
}

主线程类

public static ImageDownloadListener listner;

static ImageDownloader mainThread;

ImageDownloader(){
    mainThread = this;
    this.start();       
}

public void run(){
    System.out.println("Within the Run Method Of Main Thread size>>>>>"+requestQueue.size());   
    while (true) {
        if(_stop)
            return ;
        if(requestQueue.size()>1){          
            while(count<2){
                CustomWorkerThread threader = (CustomWorkerThread)requestQueue.elementAt(0);
                requestinProgressQueue.addElement(threader);
                Thread th = new Thread(threader);
                th.start();
                count++;
                requestQueue.removeElementAt(0);
            }
        }else{
            //mainThread.run();
            synchronized (requestQueue) {
                try {
                    requestQueue.wait(1000);
                } catch (InterruptedException e) {
                }
            }
        }
    }
}   

public static void loadImageThread(CustomWorkerThread thread){
    System.out.println("Simple Counter>>>"+simplecount);
    synchronized (requestQueue) {
            requestQueue.addElement(thread);
            requestQueue.notify();
    }

    simplecount++;          
}

public synchronized void stop(){        
    _stop = true;               
}

public  static void Reload(){
    if(requestQueue.size()>=1){         
        while(count<2){
            CustomWorkerThread threader = (CustomWorkerThread)requestQueue.elementAt(0);
            requestinProgressQueue.addElement(threader);
            Thread th = new Thread(threader);
            th.start();
            count++;
            requestQueue.removeElementAt(0);
        }
    }

}

public synchronized static void stopAllThreads(){
    if(requestQueue.size()>=1){
        for(int i=0;i<requestinProgressQueue.size();i++){
            CustomWorkerThread threaderinProgress = (CustomWorkerThread)requestQueue.elementAt(i);
            threaderinProgress.stop = true;
            threaderinProgress = null;
        }
        _stop = true;
        requestQueue.removeAllElements();
    }

}

}

自定义工作线程类

public class CustomWorkerThread implements Runnable{

    public String url;
    private boolean _stop;
    HttpConnection connection;
    ImageDownloadListener listener;
    public boolean stop = false;

    CustomWorkerThread(String _url, ImageDownloadListener _listener){
        System.out.println("On Creating CustomWorkerThread >>>>>>>>"+_url);
        url = _url ;
        listener = _listener;
    }

    public byte[] getBytesData(){
        try{
            MyConnectionFactory _factory = new MyConnectionFactory();
            ConnectionDescriptor con=_factory.getConnection(url); 
            connection=(HttpConnection) con.getConnection();
            System.out.println("connectionUrl:"+connection.getURL());
            byte [] _data=null;
            InputStream is=null;
            ByteArrayOutputStream byteArray=new ByteArrayOutputStream();            
            try {           
                int rc = connection.getResponseCode();
                if(rc == HttpConnection.HTTP_OK) {          
                    is =  connection.openInputStream();
                    _data = new byte[10240*5];
                    int bytesRead=0;
                    while ((bytesRead = is.read(_data))!= -1){
                        byteArray.write(_data,0,bytesRead);
                    }
                    byte[] bData=byteArray.toByteArray();                    
                    return bData;

                }
            }catch (IOException e1) {
                System.out.println("Exception in Reading Data"+e1);
                stop = true;
            }finally {
                try {
                      if (is != null) is.close();        
                      if (connection != null) connection.close();
                    } catch (Exception e) {
                        stop = true;
                    }
           }
        }catch(Exception e){
            System.out.println("Exception in getting Server Data"+e);
            stop = true;
        }
        return null;
    }

    public void run(){
        if(stop)
            return;
        byte[] image = this.getBytesData();
        listener.imageDownloaded(image);
        System.out.println("Response Recieved From :>>>>>>>>"+url);
        this.stop();
    }

    public synchronized void stop(){
        stop = true;
        ImageDownloader.count--;
        ImageDownloader.requestinProgressQueue.removeElement(this);
        ImageDownloader.Reload();
        System.out.println("On Stop CustomWorkerThread >>>>>>>>"+url);
    }                       
}

Answer 1

在退出应用程序之前，请勿致电ImageDownloader.stop()。这将使run方法保持运行/等待。

如何处理线程

1 个答案: