springboot上传下载文件原来这么丝滑

我使用了hutool的 FileUtil，IdUtil，所以需要引入hutool：

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
            <version>5.8.11</version>
        </dependency>

application.yml 中定义上传文件目录：

files:
  upload:
    path: D:/java_workspace/springboot_demo/upload/

上传页面：

<form action="/files/upload" method="post" enctype="multipart/form-data">
    <div><input type="file" name="file"></div>
    <div><input type="submit" value="上传"></div>
</form>

上传下载处理：

package com.example.demo.controller;

import cn.hutool.core.io.FileUtil;
import cn.hutool.core.util.IdUtil;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.net.URLEncoder;
import java.util.HashMap;

@RestController
@ResponseBody
@RequestMapping(value ="/files")
public class Files {
    @Value("${files.upload.path}")
    private String fileUploadPath;

    //上传
    @PostMapping(value ="/upload")
    public String upload(@RequestParam MultipartFile file, HttpServletRequest request, HttpServletResponse response) throws IOException {
        String originalFilename = file.getOriginalFilename(); //文件名.jpg
        String type = FileUtil.extName(originalFilename);//.jpg
        long size = file.getSize();//大小

        String uuid = IdUtil.fastSimpleUUID();
        String filename = uuid + "." + type;
        File uploadFile = new File(fileUploadPath +"/"+ filename);

        //先存储到磁盘
        if (!uploadFile.getParentFile().exists()) {
            uploadFile.getParentFile().mkdirs();
        }

        file.transferTo(uploadFile);

        request.setCharacterEncoding("utf-8");
        response.setCharacterEncoding("utf-8");
        response.setHeader("Content-Type", "text/html;charset=utf-8");
        response.setContentType("text/html;charset=utf-8");

        String str = "";
        str += "<html lang=\"zh-CN\">\n";
        str += "<head>\n";
        str += "<meta charset=\"utf-8\">\n";
        str += "<meta http-equiv=\"content-type\" content=\"text/html; charset=utf-8\">\n";
        str += "</head>\n";
        str += "<body>\n";
        str += "file: "+originalFilename+" upload success, <br /><a href='/files/download/"+filename+"' target" +
                "='_blank'>download" +
                "</a" +
                ">\n";
        str += "</body>\n";
        str += "</html>\n";

        return str;
    }

    //下载
    @GetMapping("/download/{filename}")
    public void download(@PathVariable String filename, HttpServletResponse response) throws IOException {
        File uploadFile = new File(fileUploadPath +"/"+ filename);
        ServletOutputStream os = response.getOutputStream();
        response.addHeader("Contene-Disposition","attachment;filename="+ URLEncoder.encode(filename,"UTF-8"));
        response.setContentType("application/octet-stream");

        os.write(FileUtil.readBytes(uploadFile));
        os.flush();
        os.close();
    }
}