JavaWeb-response 下载文件-2023-04-05

package com.feijian.servlet;

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.io.InputStream;
import java.net.URLEncoder;

public class Response extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //1、获取下载文件的路径
        String realPath = "E:\\JAVA\\JW\\javaweb\\Demo02\\src\\main\\resources\\飞剑.png";
        System.out.println("下载文件路径："+realPath);
        //2、下载文件名 精妙的做法
        String filename = realPath.substring(realPath.lastIndexOf("\\") + 1);
        //3、让浏览器支持下载的东西
        resp.setHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename,"UTF-8"));
        //4、获得下载文件的输入流
        FileInputStream in = new FileInputStream(realPath);
        //5、创建缓冲区
        int len =0;
        byte[] buffer = new byte[1024];
        //6、获取outputStream对象
        ServletOutputStream out = resp.getOutputStream();
        //7、写入缓冲区
        while((len=in.read(buffer))>0){
           out.write(buffer,0,len);
        }
        //8、缓冲区内容输出到客户端
        in.close();
        out.close();
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req, resp);
    }
}