HttpServletResponse下载文件

简称Response类

常见应用

1. 向浏览器输出消息
2. 下载文件
   1. 要获取下载文件的路径
   2. 下载文件的名称
   3. 设置想办法让浏览器能够支持下载我们需要的东西
   4. 获取下载文件的输入流
   5. 创建缓冲区
   6. 获取OutputStream对象
   7. 将FileOutputStream流写入到debuffer缓冲区
   8. 使用OutputStream将缓冲区的数据输出到客户端！

 

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package com.yin;   import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.FileInputStream; import java.io.IOException; import java.net.URLEncoder;   public class servlet1 extends HttpServlet {     @Override     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         //要获取下载文件的路径         //String realPath=this.getServletContext().getRealPath("/1.png");         String realPath="E:\\code\\maven0\\response1\\src\\main\\resources\\1.png";           System.out.println("下载文件的路径:"+realPath);         //下载文件的名称         String filename=realPath.substring(realPath.lastIndexOf("\\")+1);         //设置想办法让浏览器能够支持下载我们需要的东西         //resp.setHeader("Content-Disposition", "attachment; filename="+ URLEncoder.encode(filename,"utf-8"));//可解决中文名乱码         resp.setHeader("Content-Disposition", "attachment; filename="+filename);         //获取下载文件的输入流         FileInputStream in= new FileInputStream(realPath);         //创建缓冲区         int len=0;         byte[] buffer=new byte[1024];         //获取OutputStream对象         ServletOutputStream out =resp.getOutputStream();           //将FileOutputStream流写入到buffer缓冲区//使用OutputStream将缓冲区的数据输出到客户端！         while( (len=in.read(buffer))>0)             out.write(buffer,0,len);           in.close();         out.close();       }       @Override     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         super.doGet(req, resp);     } }