SpingMVC 九、文件上传和下载-CFANZ编程社区

1、文件下载
使用ResponseEntity实现下载文件的功能
代码：
package com.sun.mvc.contorller;

import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.MultiValueMap;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSession;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * @author sunyc
 * @create 2022-04-18 18:13
 */
@Controller
public class FileUpAndDownController {
    @RequestMapping("/testFileter")
    public String testFileter(){
        return "filter";
    }

    @RequestMapping("/testDown")
    public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws
            IOException {
        //获取ServletContext对象的工程路径
        ServletContext servletContext = session.getServletContext();
        //获取服务器中文件的真实的服务器的部署工程路径
        String realPath = servletContext.getRealPath("/static/img/1.jpg");
        System.out.println("获取服务器中文件的真实的服务器的部署工程路径:"+realPath);
        //创建输入流
        InputStream is = new FileInputStream(realPath);
        //创建字节数组
        byte[] bytes = new byte[is.available()];
        //将流读到字节数组中
        is.read(bytes);
        //创建HttpHeaders对象设置响应头信息
        MultiValueMap<String, String> headers = new HttpHeaders();
        //设置要下载方式以及下载文件的名字
        headers.add("Content-Disposition", "attachment;filename=1.jpg");
        //设置响应状态码
        HttpStatus statusCode = HttpStatus.OK;
        //创建ResponseEntity对象
        ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers,
                statusCode);
        //关闭输入流
        is.close();
        return responseEntity;

    }
}


filter.xml
<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>测试文件上传和下载</title>
</head>
<body>
<h1>filter 页面</h1>

<a th:href="@{/testDown}" >下载文件</a>
</body>
</html>