工程包文件：commons-io-1.1.jar、config.properties、download.jar、start.bat

说明：借助Apache Commons IO工具包（commons-io-1.1.jar）来简单实现文件（夹）的复制、移动、删除、获取大小等操作

config.properties 文件内容：

#远程服务器下载url

remoteUrl=http://localhost:8080/test/download/a.mp3

#下载文件保存位置如F:\download

saveFileUrl=F

#并发下载线程数

threadNums=10

start.bat文件内容：

set classpath=download.jar;commons-io-1.1.jar

java FileSave

pause

download.jar 文件主class文件源码： 

import java.io.File;

import java.net.URL;

import java.util.Random;

import org.apache.commons.io.FileUtils;

public class FileSave

{

 static String remoteUrl = "3";

 static String saveFileUrl = "D:/download/";

 public static void main(String[] args)

 {

  for (int i = 0; i < 500; i++)

  {

   new Thread(new myThread(remoteUrl, saveFileUrl)).start();

  }

 }

}

class myThread implements Runnable

{

 int NUM = 1;

 String remoteUrl = "";

 String saveFileUrl = "";

 public myThread(String remoteUrl, String saveFileUrl)

 {

  this.remoteUrl = remoteUrl;

  this.saveFileUrl = saveFileUrl;

 }

 public void run()

 {

  downloadFromUrl(remoteUrl, saveFileUrl);

 }

 /**

  * 文件下载的方法

  */

 public static String downloadFromUrl(String url, String dir)

 {

  String fileName = "";

  try

  {

   URL httpurl = new URL(url);

   String[] us = url.split("/");

   fileName = us[us.length - 1];

   String ramdom = System.currentTimeMillis() + ""

     + new Random().nextInt(100);

   fileName = ramdom + "_" + fileName;

   System.out.println("fileName:" + fileName);

   File f = new File(dir + fileName);

   FileUtils.copyURLToFile(httpurl, f);

  } catch (Exception e)

  {

   e.printStackTrace();

   return "Fault!";

  }

  return fileName;

 }

}