<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-mongodb</artifactId>
</dependency>

#文件上傳下載配置
spring.servlet.multipart.max-file-size=1024MB
spring.servlet.multipart.max-request-size=1024MB

package com.example.tryRedis.controller;
import static org.springframework.data.mongodb.core.query.Query.*;
import static org.springframework.data.mongodb.gridfs.GridFsCriteria.*;
import com.mongodb.client.gridfs.model.GridFSFile;
import io.swagger.v3.oas.annotations.Parameter;
import org.bson.types.ObjectId;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.mongodb.gridfs.GridFsOperations;
import org.springframework.data.mongodb.gridfs.GridFsResource;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.util.HashMap;
import java.util.Map;
@RestController
@RequestMapping("/file")
public class FileController {
    @Autowired
    GridFsOperations gridFsOperations;
    //上傳文件
    @PostMapping(value = "/upload",consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
    public Map<String , ObjectId> upload(@Parameter @RequestPart(value = "file") MultipartFile file){
        //開(kāi)始時(shí)間
        long begin = System.nanoTime();
        Map<String,ObjectId> map = new HashMap<>();
        try{
            InputStream streamForUpload = file.getInputStream();
            ObjectId objectId = gridFsOperations.store(streamForUpload,file.getOriginalFilename(),file.getContentType());
            //上傳結(jié)束
            long end = System.nanoTime();
            long time = end-begin;
            System.out.println("本次上傳共耗時(shí): "+ time);
            System.out.println("上傳成功！文件名: "+file.getOriginalFilename()+". 文件ID: "+objectId);
            map.put(file.getOriginalFilename(),objectId);
        }catch (Exception e){
            e.printStackTrace();
        }
        return map;
    }
    //查詢并下載文件
    @GetMapping("/download")
    public String download(String filename, HttpServletResponse response) throws IOException {
        //開(kāi)始時(shí)間
        long begin = System.nanoTime();
        //查詢文件
        GridFSFile result  = gridFsOperations.findOne(query(whereFilename().is(filename)));
        GridFsResource gridFsResource= gridFsOperations.getResource(result);
        String contentType = gridFsResource.getContentType();
        System.out.println("contentType: "+contentType);
        System.out.println("filename: "+gridFsResource.getFilename());
        response.reset();
        response.setContentType(contentType);
        //注意: 如果沒(méi)有下面這行設(shè)置header, 結(jié)果會(huì)將文件的內(nèi)容作為響應(yīng)的 body 直接輸出在頁(yè)面上, 而不是下載文件
        response.setHeader("Content-Disposition","attachment;filename="+filename);  //指定下載文件名
        ServletOutputStream outputStream = response.getOutputStream();
        InputStream is = gridFsResource.getInputStream();
        byte[] bytes = new byte[1024];
        int len = 0;
        while ((len=is.read(bytes))!=-1){
            outputStream.write(bytes,0,len);
        }
        is.close();
        outputStream.close();
        //下載結(jié)束
        long end = System.nanoTime();
        long time = end-begin;
        System.out.println("本次下載共耗時(shí): "+ time);
        return contentType;
    }
    @DeleteMapping("/delete")
    public String deleteFile(@Parameter @RequestParam("filename") String filename){
        gridFsOperations.delete(query(whereFilename().is(filename)));
        return "delete success";
    }
}