SpringBoot上传、下载文件

页面内容

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>单文件上传</title>
</head>
<body>
<h3>单文件上传</h3>
<form method="post" action="/file/upload" enctype="multipart/form-data">
  <input type="file" name="file">
  <input type="submit" value="提交">
</form>

<h3>多文件上传</h3>
<form method="post" action="/file/uploads" enctype="multipart/form-data">
    <input type="file" multiple name="file">
    <input type="submit" value="上传">
</form>
</body>
</html>

=========================================================================

后台逻辑

package com.cn.Controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;
import org.springframework.web.multipart.MultipartHttpServletRequest;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.util.List;
import java.util.UUID;

@Controller
@RequestMapping("/file/")
public class FileController {
    /*单文件上传*/
    @RequestMapping("upload")
    @ResponseBody
    public String upload(@RequestParam("file")MultipartFile file){
        //获取原始名字
        String fileName = file.getOriginalFilename();
        //获取后缀名
        String suffixName = fileName.substring(fileName.lastIndexOf("."));
        //文件保存路径
        String filePath = "d:/file/";
        //文件重命名，防止重复
        fileName = filePath+ UUID.randomUUID() + fileName;
        //文件对象
        File dest = new File(fileName);
        //判断路径是否存在，不存时创建
        if(!dest.getParentFile().exists()){
            dest.getParentFile().mkdir();
        }
        try {
            //将文件保存到服务器
            file.transferTo(dest);
            System.out.println("================");
            return "上传成功";
        }catch (Exception e){
            e.printStackTrace();
        }
        return"上传失败";
    }
    @RequestMapping("/uploads")
    @ResponseBody
    public String handleFileUpload(HttpServletRequest request){
        List<MultipartFile> files = ((MultipartHttpServletRequest)request).getFiles("file");
        MultipartFile file = null;
        for(int i = 0;i < files.size();i++){
            file = files.get(i);
            if(!file.isEmpty()){
                try {
                    //获取原始名字
                    String fileName = file.getOriginalFilename();
                    //文件保存路径
                    String filePath = "d:/file/";
                    //防止文件重命名
                    fileName = filePath + UUID.randomUUID()+fileName;
                    //文件对象
                    File dest = new File(fileName);
                    //保存到服务器
                    file.transferTo(dest);
                }catch (Exception e){
                    e.printStackTrace();
                    return"上传失败";
                }
            }else{
                return"上传失败";
            }
        }
        return"上传成功";
    }

    @RequestMapping("/download")
    public void download(HttpServletResponse response) throws Exception{
        //文件地址
        String fileName = "a.txt";
        String filePath = "D:/file";

        File file = new File(filePath+"/"+fileName);
    //创建输入对象
        FileInputStream fis = new FileInputStream(file);
        //设置相关格式
        response.setContentType("application/force-download");
        //设置下载后的文件名及handler
        response.setHeader("Content-Disposition","attachement;fileName =" + fileName);
        //创建输出对象
        OutputStream os = response.getOutputStream();

        //常规操作
        byte[]buf = new byte[1024];
        int len = 0;
        while ((len = fis.read(buf)) != -1){
            os.write(buf,0,len);
        }
        fis.close();
    }
}