springboot实现文件上传下载接口

package org.example.controller;

import jakarta.servlet.ServletOutputStream;
import jakarta.servlet.http.HttpServletResponse;
import org.example.pojo.Result;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URLEncoder;
import java.util.UUID;

/**
 * 文件处理接口
 */
@RestController
public class FileUploadController {
    private static final String FILE_PATH = System.getProperty("user.dir")+"\\src\\main\\resources\\static\\img\\upload\\";
    /**
     *上传文件
     */
    @PostMapping("/upload")
    public Result<String> upload(MultipartFile file) throws IOException
    {
        //获取文件磁盘的输入流 写入到本地磁盘文件
        String originalFilename = file.getOriginalFilename();
        //保证文件名唯一  防止文件覆盖
        String fileName = UUID.randomUUID().toString()+ originalFilename.substring(originalFilename.lastIndexOf("."));
        //把文件保存到项目文件夹中
        file.transferTo(new File(FILE_PATH + fileName));
        return Result.success(fileName);
    }
    /**
    * 文件查看
    */
    @GetMapping("/file")
    public void file(@RequestParam("url") String filename, HttpServletResponse response) throws IOException {
        //设置输出流格式
        ServletOutputStream os = response.getOutputStream();
        response.addHeader("Content-Disposition", "attachment;filename=" + URLEncoder.encode(filename, "UTF-8"));
        //设置文件类型  任意类型的二进制流数据
        response.setContentType(MediaType.APPLICATION_OCTET_STREAM_VALUE);
        //读取文件字节流
        InputStream is = new FileInputStream(FILE_PATH+filename);
        os.write(is.readAllBytes());
        //刷新输出流
        os.flush();
        //关闭输出流
        os.close();
    }
}