急急急！我用servlet來打開一個excel文件，但為何只讓我下載呀，請教啦各位，源碼如下：

[bellfeel]

我想用servlet來在ie里打開excel文件，但我一調用此servlet時，它就讓我下載此文件，何解呀，

public void performTask(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)
throws ServletException, IOException

{
response.setContentType( "application/vnd.ms-excel" ); // MIME type
String fileURL = "http://david/gmims/chinese/test/book1.xls";
response.setHeader("Content-disposition",
"attachment; filename=book1.xls" );
BufferedInputStream bis = null;
BufferedOutputStream bos = null;

try {
ServletOutputStream out = response.getOutputStream ();

URL url = new URL( "http", "david", 80, fileURL );

// Use Buffered Stream for reading/writing.
bis = new BufferedInputStream(url.openStream());
bos = new BufferedOutputStream(out);

byte[] buff = new byte[2048];
int bytesRead;

// Simple read/write loop.
while(-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
bos.write(buff, 0, bytesRead);
}
System.out.println("test excel");

} catch(Exception e) {
System.out.println ( "excel error."+e.toString() );

} finally {
if (bis != null)
bis.close();
if (bos != null)
bos.close();
}
}