Spring Boot - File Handling

在这个章节，我们将学习如何通过web服务上传以及下载文件。

File Upload

为了上传文件，你可以使用MultipartFile作为请求参数，并且此API应该使用Multi-part form数据。
代码如下：

package com.restfulapio.demo.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

@RestController
public class FileUploadController {
    @RequestMapping(value = "/upload",method = RequestMethod.POST)
    public String fileUpload(@RequestParam("file") MultipartFile file) throws IOException {
        File convertFile = new File("D:\\tmp\\"+file.getOriginalFilename());
        convertFile.createNewFile();
        FileOutputStream fout = new FileOutputStream(convertFile);
        fout.write(file.getBytes());
        fout.close();
        return "File is upload successfully";
    }
}

File Download

我们需要使用InputStreamResource来下载文件，并且设置响应头信息Content-Disposition以及指定响应Media Type
代码如下：

package com.restfulapio.demo.controller;

import org.springframework.core.io.InputStreamResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

@RestController
public class FileDownloadController {

    @RequestMapping(value = "/download",method = RequestMethod.GET)
    public ResponseEntity<Object> downloadFile() throws IOException  {
        String filename = "D:\\tmp\\test.txt";
        File file = new File(filename);
        InputStreamResource resource = new InputStreamResource(new FileInputStream(file));
        HttpHeaders headers = new HttpHeaders();

        headers.add("Content-Disposition", String.format("attachment; filename=\"%s\"", file.getName()));
        headers.add("Cache-Control", "no-cache, no-store, must-revalidate");
        headers.add("Pragma", "no-cache");
        headers.add("Expires", "0");

        ResponseEntity<Object>
                responseEntity = ResponseEntity.ok().headers(headers).contentLength(
                file.length()).contentType(MediaType.parseMediaType("application/txt")).body(resource);

        return responseEntity;
    }
}

测试