用java实现多线程下载

以下是代码片段：

package com.util.file;

public class Files {

    /***
     * 获取应用程序的根目录
     * @return 应用程序根目录
     */
    public static String getSysPath(){
 return  System.getProperty("user.dir");
    }

   
}

以下是代码片段：

<PRE class=csharp name="code">package com.core.crawl;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

import com.core.http.Http;

public class WebSpider implements Runnable{
   
    private Http http = new Http();

    private String webAddress = "";
    private String destFile = "";
   
    public void setWebAddress(String webAddress){
 this.webAddress = webAddress;
    }
   
    public void setDestFile (String destFile){
 this.destFile = destFile;
    }
   
    public boolean download() throws IOException, InterruptedException {

 HttpURLConnection httpConn = null;

 try {
     URL url = new URL(webAddress);
  
     httpConn = (HttpURLConnection) url.openConnection();
     httpConn.setRequestMethod("GET");
     httpConn.setRequestProperty("User-Agent", "Mozilla/5.0 (Windows; U; Windows NT 5.1; zh-CN; rv:1.8.1.14) Gecko/20080404 Firefox/2.0.0.14");
     InputStream in = httpConn.getInputStream();
     String fileType = http.fileType(httpConn.getContentType());
     System.out.println(fileType);
     FileOutputStream out = new FileOutputStream(new File(destFile + fileType));
     int chByte = in.read();
     while (chByte != -1) {
  out.write(chByte);
  //System.out.println(chByte);
  chByte = in.read();
     }
 } catch (Exception ex) {
     System.out.println(ex.toString());
 } finally {
     httpConn.disconnect();
 }
 return true;
    }

    public void run() {
 try {
     //System.out.println(Thread.currentThread().getName());
     download();   
 } catch (IOException e) {
     e.printStackTrace();
 } catch (InterruptedException e) {
     e.printStackTrace();
 }
    }
}
</PRE>

以下是代码片段：

<PRE class=csharp name="code">package com.core.crawl;

import java.io.IOException;

import com.util.file.Files;

public class Crawl {

    /**
     * @param args
     * @throws IOException
     * @throws InterruptedException
     */
    public static void main(String[] args) throws IOException, InterruptedException {

 long begin = System.currentTimeMillis();
 WebSpider spider2 = new WebSpider();
 WebSpider spider1 = new WebSpider();
 spider1.setWebAddress("http://www.163.com");
 spider1.setDestFile(Files.getSysPath() + "/"+"spider1.");
 
 spider2.setWebAddress("http://blog.csdn.net/longronglin");
 spider2.setDestFile(Files.getSysPath() + "/"+"spider2.");

 Thread t1 = new Thread(spider1);
 Thread t2 = new Thread(spider2);
 t1.start();
 t2.start();

 t1.join();
 t2.join();
 
 System.out.println("the end");
 System.out.println(System.currentTimeMillis() - begin);
    }
   

}</PRE>
<PRE class=csharp name="code">&nbsp;</PRE>
<PRE class=csharp name="code">测试通过：</PRE>
<PRE class=csharp name="code"></PRE>