jsp下載文件

package baza;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class Download extends HttpServlet {

        public void doGet(HttpServletRequest sreq,
                          HttpServletResponse sres){

                          OutputStream out;
                          String file;
                          String content;
                          file=sreq.getParameter("file");

                          try {
                                File f=new File(file);
                                String contentType;
                                long filesize=f.length();
                                byte b;
                                int i=0;
                                FileInputStream fin=new FileInputStream(f);

                                        contentType="application/octet-stream";
                                if(file.endsWith(".au")) contentType="audio/basic";
                                if(file.endsWith(".avi")) contentType="video/x-msvideo";
                                if(file.endsWith(".bmp")) contentType="image/bmp";
                                if(file.endsWith(".css")) contentType="text/css";
                                if(file.endsWith(".doc")) contentType="application/msword";
                                if(file.endsWith(".dll")) contentType="application/x-msdownload";
                                if(file.endsWith(".exe")) contentType="application/x-msdownload";
                                if(file.endsWith(".gif")) contentType="image/gif";
                                if(file.endsWith(".jpg")) contentType="image/jpeg";
                                if(file.endsWith(".jpeg")) contentType="image/jpeg";
                                if(file.endsWith(".jpg")) contentType="image/jpeg";
                                if(file.endsWith(".js")) contentType="application/x-javascript";
                                if(file.endsWith(".mid")) contentType="audio/midi";
                                if(file.endsWith(".midi")) contentType="audio/midi";
                                if(file.endsWith(".mov")) contentType="video/quicktime";
                                if(file.endsWith(".htm")) contentType="text/html";
                                if(file.endsWith(".html")) contentType="text/html";
                                if(file.endsWith(".zip")) contentType="application/x-zip-compressed";

                                sres.setContentType(contentType);
                                sres.setContentLength((int)filesize);
                                sres.setHeader("Content-Disposition","attachment;file=/""+f.getName()+"/"");

                                        out=sres.getOutputStream();

                                while(i!=filesize) {
                                        if(!f.exists()) {
                                                fin.close();
                                                sres.sendRedirect("udError.html");
                                                }
                                        b=(byte)fin.read();
                                        out.write(b);
                                        i++;}

 

}
catch(IOException ioe) {}

 

}
}