使用Servlet实现下载文件的功能

import java.io.File;  
import java.io.FileInputStream;  
import java.io.IOException; 
import java.net.URLEncoder;    
import javax.servlet.ServletException; 
import javax.servlet.ServletOutputStream; 
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;    
          public class DownLoadServlet extends HttpServlet {              
                 
                  public void doGet(HttpServletRequest request, HttpServletResponse response)              
                                throws ServletException, IOException {          
                                doPost(request,response);      
                                }              
                  public void doPost(HttpServletRequest request, HttpServletResponse response)              
                                throws ServletException, IOException {          
                                //处理请求          
                                //读取要下载的文件          
                                File f = new File("E:/好久不见.mp3");          
                                if(f.exists()){              
                                  FileInputStream  fis = new FileInputStream(f);              
                                  String filename=URLEncoder.encode(f.getName(),"utf-8"); //解决中文文件名下载后乱码的问题              
                                  byte[] b = new byte[fis.available()];              
                                  fis.read(b);             
                                  response.setCharacterEncoding("utf-8");              
                                  response.setHeader("Content-Disposition","attachment; filename="+filename+"");                       //获取响应报文输出流对象              
                                    ServletOutputStream  out =response.getOutputStream();              //输出              
                                    out.write(b);              
                                    out.flush();              
                                    out.close();          
                                    }                  
                              }         
                  }    
}