response实现文件下载

 package cn.itcast.response;

 import java.io.FileInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;

 import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 public class ResponseDemo extends HttpServlet {

     public void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

         String path = this.getServletContext().getRealPath("/download/日本妞.jpg");
         String filename = path.substring(path.lastIndexOf("\\") + 1);

         //如果下载文件是中文文件，则文件名需要经过URL编码
         response.setHeader("content-disposition", "attachment;filename="
                 + URLEncoder.encode(filename,"UTF-8"));

         InputStream in = null;
         OutputStream out = null;

         in = new FileInputStream(path);
         int len = 0;
         byte buffer[] = new byte[1024];

         out = response.getOutputStream();
         while ((len = in.read(buffer)) > 0) {
             out.write(buffer, 0, len);
         }

         in.close();
         out.close();

     }

     public void doPost(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {

     }

 }