文件下载功能

import java.io.FileInputStream;  
    import java.io.IOException;  
    import java.io.OutputStream;  
      
    import javax.servlet.ServletException;  
    import javax.servlet.http.HttpServlet;  
    import javax.servlet.http.HttpServletRequest;  
    import javax.servlet.http.HttpServletResponse;  
      
    public class ResponseDownload extends HttpServlet {  
        public void doGet(HttpServletRequest request, HttpServletResponse response)  
                throws ServletException, IOException {  
            //String realpath = this.getServletContext().getRealPath("/2.jpg");//获得下载图片路径  
            String realpath = this.getServletContext().getRealPath("/图片.jpg");//中文名称文件  
     　　　　String filename = realpath.substring(realpath.lastIndexOf("\\") + 1);//截取路径获得下载文件名  
   　　　　　response.setHeader("content-disposition", "attachment;filename="+URLEncoder.encode(filename, "UTF-8"));//中文名称文件的下载  
    　　　　 //response.setHeader("content-disposition", "attachment;filename="+filename);//response 响应头响应下载请求  
    　　　　 FileInputStream in =new FileInputStream(realpath); //将图片文件以流写入  

            int len=0;   
            byte buffer[]=new byte[1024];  
            OutputStream out = response.getOutputStream();  

           while((len=in.read(buffer))>0){ //读取文件模板代码 ,需记住  
    　    　out.write(buffer, 0, len);
　　　      }
　　　　    in.close();
   }　　
   public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
　　　　　　　　doGet(request, response);
　　}
}