文件上传和下载

import com.rome.backend.common.R;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;

import java.io.IOException;
import java.util.UUID;

/**
 * 文件上传下载
 */
@RestController
@RequestMapping("/common")
public class CommonController {
    /**
     * 上传
     * @param file
     * @return
     */
    @PostMapping("/upload")
    public R<String> upload(MultipartFile file){//参数名和前端input名一样
        //file是一个临时文件，需要转存到指定位置，否则本次请求完成后临时文件会删除
        //获取当前项目路径进行拼接
       String url = System.getProperty("user.dir")+"\\backend\\src\\main\\resources\\backend\\images\\dish\\dishload\\";
       //使用uuid重新生成文件名防止文件名重复造成覆盖，uuid+原始文件名
        String uuid = UUID.randomUUID().toString();
//        uuid+原始文件名
        String fileName = uuid.concat(file.getOriginalFilename());

//        将文件转存
        try {
            file.transferTo(new File(url+fileName));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return R.success(fileName);
    }

    /**
     * 下载
     * @param name
     * @param response
     */
    @GetMapping("/download")
    public void download(String name, HttpServletResponse response){
        //图片路径
        String urlImg = System.getProperty("user.dir")+"\\backend\\src\\main\\resources\\backend\\images\\dish\\dishload\\".concat(name);
        try {
            //通过输入流读取文件内容
            FileInputStream fileInputStream = new FileInputStream(new File(urlImg));
            

            //输出流到浏览器

            ServletOutputStream outputStream = response.getOutputStream();

            //设置响应回去的是什么类型的文件
            response.setContentType("image/jpeg");

            int len = 0;
            byte[] bytes = new byte[1024];
            while ((len = fileInputStream.read(bytes)) != -1){
                outputStream.write(bytes,0,len);
                outputStream.flush();
            }
            //关闭资源
            outputStream.close();
            fileInputStream.close();

        } catch (Exception e) {
           e.printStackTrace();
        }
      
    }
}