1 //1、声明URL 2         String path="http://localhost:8080/day22_DownLoad/file/a.rmvb"; 3         URL url=new URL(path); 4         //2、设置已下载文件 5         String savePath="d:\\a.rmvb"; 6         File file=new File(savePath); 7         long size=file.length();//文件当前大小，刚开始时返回0 8         System.out.println(size); 9         //3、设置连接10         HttpURLConnection conn=  (HttpURLConnection) url.openConnection();11         //4、设置访问类型12         conn.setRequestMethod("GET");13         //5、设置下载区间14         conn.setRequestProperty("range","bytes="+size+"-");15         conn.connect();16         //6、状态码17         int code=conn.getResponseCode();//断点是20618         if(code==206)19         {20             InputStream in=conn.getInputStream();21             int serviceSize=conn.getContentLength();22             //必须使用23             RandomAccessFile out=new RandomAccessFile(file, "rw");24             //从size字节开始写25             out.seek(size);26             byte[] b=new byte[1024];27             int len=-1;28             while((len=in.read(b))!=-1)29             {30                 out.write(b,0,len);31             }32             out.close();33         }