Springboot接收文件与发送文件实例教程

import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;
import javax.servlet.http.HttpServletRequest;
import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;

<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="file" name="multipartfile" accept="image/png" value="请选择文件">
    <input type="submit" value="上传">
</form>

@RestController
public class uploadcontroller {
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
    @PostMapping("/upload")
    public String upload(MultipartFile multipartfile, HttpServletRequest request){
        String realPath = request.getSession().getServletContext().getRealPath("/update/");
        String format=sdf.format(new Date());
        File folder=new File(realPath+format);
        if(!folder.isDirectory()){
            folder.mkdirs();
        }
        String oldname = multipartfile.getOriginalFilename();
        String newname = UUID.randomUUID().toString()+oldname.substring(oldname.lastIndexOf("."),oldname.length());
        try {
            multipartfile.transferTo(new File(folder, newname));
            System.out.println(new File(folder, newname).getAbsolutePath());//输出（上传文件）保存的绝对路径
            String filePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+"/update/"+format+newname;
            return filePath+"上传成功";
        }
        catch (IOException e){
            e.printStackTrace();
        }
        return "上传失败!";
    }
}

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.OutputStream;
import java.io.IOException;

<a href="/load" rel="external nofollow"  download="file">下载文件</a>

@RestController
public class loadcontroller {
    @GetMapping("/load")
    public void fileload( HttpServletResponse response) throws IOException {
        File f = new File("C:\\Users\\Java\\Desktop\\新建 文本文档.txt");
        FileInputStream ips = new FileInputStream(f);
        OutputStream ops = response.getOutputStream();
        response.setContentType("application/octet-stream; charset=UTF-8");
        byte[] a = new byte[1000];
        ips.read(a);
        ops.write(a);
    }
}
//本代码在执行结束后并没有手动关闭对应的io流，读者可自行解决