take_out/src/main/java/cn/edu/hactcm/cotroller/CommonController.java

package cn.edu.hactcm.cotroller;

import cn.edu.hactcm.common.R;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import javax.print.DocFlavor;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.UUID;

@RestController
@Slf4j
@RequestMapping("/common")
public class CommonController {
    @Value("${takeout.path}")
    private String basePath;

    /**
     * 文件上传
     * @param file
     * @param request
     * @return
     */
    @RequestMapping("/upload")
    public R<String> upload(MultipartFile file, HttpServletRequest request){
        //获取文件的格式后缀
        String originalFilename = file.getOriginalFilename();
        String suffix = originalFilename.substring(originalFilename.lastIndexOf("."));

        //uuid
        String fileName = UUID.randomUUID().toString()+suffix;

        //如果路径不存在创建路径
        File dir = new File(basePath);
        if (!dir.exists()) {
            dir.mkdir();
        }

        //转存
        try {
            file.transferTo(new File(basePath+fileName));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        //将文件名返回浏览器，后面用户新增信息时随表单数据提交到服务器，写入数据库
        return R.success(fileName);
    }

    /**
     * 文件下载
     * @param name
     * @param response
     */
    @GetMapping("/download")
    public void download(String name, HttpServletResponse response){

        try {
            //输入流，通过输入流读取文件内容
            FileInputStream fileInputStream = new FileInputStream(new File(basePath + name));

            //输出流，通过输出流将文件写回浏览器
            ServletOutputStream outputStream = response.getOutputStream();

            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();
        }

    }
}