downlaod data from http with RandomAccessFile(muli Thread)

/**
 *
 * @author yw04009 Bill, Wu
 *
 */

 

public class TestDownLoad {
 
 public void testOneThread(String filePath, String url) throws IOException {
  File file = new File(filePath + getFileExtName(url));
  FileWriter fWriter = new FileWriter(file);
  URL ul = new URL(url);  
  URLConnection conn = ul.openConnection();  
  conn.setConnectTimeout(2000);
  InputStream in = conn.getInputStream();
  int temp = 0;
  while ((temp = in.read()) != -1) {
   fWriter.write(temp);
  }
  fWriter.close();
  in.close();
  
 }
 
 public String getFileExtName(String path) {  
        return path.substring(path.lastIndexOf("."));  
    }  
 
 
 public void testMoreThread(String filePath, String url, int tnum) throws IOException {
  final File file = new File(filePath + getFileExtName(url));  
  RandomAccessFile accessFile = new RandomAccessFile(file, "rwd");
  final URL ul = new URL(url);  
  HttpURLConnection conn = (HttpURLConnection) ul.openConnection();  
  conn.setConnectTimeout(2000);
  conn.setRequestMethod("GET");
  int len = conn.getContentLength();
        accessFile.setLength(len);  
        accessFile.close();
       
        final int block = (len + tnum - 1) / tnum; //the size for every thread download
        for (int i = 0; i < tnum; i++) {
         final int a = i;
         new Thread(new Runnable() {

          int start = block * a;  //start place
          int end = block * (a + 1) - 1; //end place
    public void run() {
     // TODO Auto-generated method stub
     HttpURLConnection conn2 = null;  
                    RandomAccessFile accessFile2 = null;  
                    InputStream in = null;
                    try {
                     conn2 = (HttpURLConnection) ul.openConnection();  
                     conn2.setConnectTimeout(2000);
                     conn2.setRequestMethod("GET");
                     conn2.setRequestProperty("Range", "bytes=" + start  
                                + "-" + end + "");//
                     in = conn2.getInputStream();  
                     byte[] data = new byte[1024];  
                     int len = 0;
                     accessFile2 = new RandomAccessFile(file, "rwd");  
                        accessFile2.seek(start);  
                       
                        while ((len = in.read(data)) != -1) {
                         accessFile2.write(data, 0, len);
                        }
                        System.out.println("This Thread Download is Compled .. ");

                    } catch (IOException e) {
                     
                    }
    }
          
         }).start();
        }
 }
 
 
 
 public static void main(String[] args) throws IOException {
  TestDownLoad test = new TestDownLoad();
  String path = "http://bill.com/test.txt";
  //test.testOneThread("C:\\code\\test1", path);
  //test.testMoreThread("C:\\code\\test2", path, 3); }

}