java实现断点续传

     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    <pre class="brush:java; toolbar: true; auto-links: false;">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");  } }</pre>转自：    <a href="/misc/goto?guid=4959220970133937754" target="_blank">http://xuehanxin.iteye.com/blog/1284272</a>