用java的URL实现了一个简单的断点续传的列子，不为别的，假如你对断点续传不了解一看就明白了呵呵，算不上高深啊
package test;import java.io.FileNotFoundException;import java.io.IOException;import java.io.InputStream;import java.io.RandomAccessFile;import java.net.MalformedURLException;import java.net.URL;import java.net.URLConnection;/* @className:TestDown.java * @classDescription: 简单的java断点续传 * @author:jiangmianyue * @createTime:2011-11-29 */public class TestDown { public static void main(String[] args) { URL url = null; try { url = new URL("http://172.16.1.33/newfile/e358beb5367341929614332e1a390dfb.apk"); } catch (MalformedURLException e) { e.printStackTrace(); } URLConnection httpConnection = null; try { // 建立连接 httpConnection = url.openConnection(); } catch (IOException e) { e.printStackTrace(); } // 设置ua httpConnection.setRequestProperty("User-Agent","NetFox"); // 设置断点续传的开始位置 从100k开始 httpConnection.setRequestProperty("RANGE","bytes=102400-"); // 获得输入流 InputStream input = null; try { input = httpConnection.getInputStream(); } catch (IOException e) { e.printStackTrace(); } // 可以从多少字节开始写的文件类 RandomAccessFile oSavedFile = null; try { oSavedFile = new RandomAccessFile("d://down.apk","rw"); } catch (FileNotFoundException e) { e.printStackTrace(); } // 从第100K开始写 long nPos = 102400; // 定位文件指针到 nPos 位置 try { // 文件指针移动到那个位置 oSavedFile.seek(nPos); } catch (IOException e) { e.printStackTrace(); } byte[] b = new byte[1024]; int nRead; // 从输入流中读入字节流，然后写到文件中 try { // int n =0; while((nRead=input.read(b,0,1024)) > 0) { oSavedFile.write(b,0,nRead); /** * 第一次的时设置n的值到100的时候断开 * if(100 == n){ * break; * } */ } } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } // 下面是一些请求头信息可以根据需要添加 private static void setHeader(URLConnection con) { con.setRequestProperty("User-Agent", "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.0.3) Gecko/2008092510 Ubuntu/8.04 (hardy) Firefox/3.0.3"); con.setRequestProperty("Accept-Language", "en-us,en;q=0.7,zh-cn;q=0.3"); con.setRequestProperty("Accept-Encoding", "aa"); con.setRequestProperty("Accept-Charset", "ISO-8859-1,utf-8;q=0.7,*;q=0.7"); con.setRequestProperty("Keep-Alive", "300"); con.setRequestProperty("Connection", "keep-alive"); con.setRequestProperty("If-Modified-Since", "Fri, 02 Jan 2009 17:00:05 GMT"); con.setRequestProperty("If-None-Match", "\"1261d8-4290-df64d224\""); con.setRequestProperty("Cache-Control", "max-age=0"); con.setRequestProperty("Referer", "http://www.dianping.com"); }}