java中一个简单的下载示例

首先在tomcat服务器下的webapps的download项目下建一个doc文件夹,再建个test.doc.防止控指针异常

DownLoad.java代码

 package com.down;

 import java.io.IOException;
 import java.io.InputStream;

 import javax.servlet.ServletException;
 import javax.servlet.ServletOutputStream;
 import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;

 @WebServlet(
         name="download",
         urlPatterns={"/test"}
         )
 public class DownLoad extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp)
             throws ServletException, IOException {
         doGet(req, resp);
     }
     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
             throws ServletException, IOException {
         response.setContentType("application/msword");
         response.addHeader("Content-disposition","attachment;filename=test.doc");
         InputStream in=getServletContext().getResourceAsStream("/doc/test.doc");
         ServletOutputStream os=response.getOutputStream();
         byte[] bytes=new byte[1024];
         int len=-1;
         while((len=in.read(bytes))!=-1){
             os.write(bytes,0,len);
         }
         in.close();
         os.close();
     }
 }

运行结果: