Spring Boot 文件處理

Spring Boot 文件處理

對於文件上傳或者下載，我們需要關注是Request Headers 或 Response Headers 中的Content-type 屬性

文件上傳

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對於文件上傳，必須使用 MultipartFile 作爲請求參數並且api中consume屬性要爲 MULTIPART_FORM_DATA_VALUE 。代碼如下

@RequestMapping(value = "/upload", method = RequestMethod.POST, consumes = MediaType.MULTIPART_FORM_DATA_VALUE)

public String fileUpload(@RequestParam("file") MultipartFile file) {
   return null;
}

完整的代碼如下

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

通過PostMan來測試，需要主要的是：設置請求頭head的Content-Type:multipart/form-data；填寫body選擇form-data，然後選擇文件。詳細步驟可以參考：這裏

文件下載

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文件下載

對於文件下載，要InputStreamResource類來下載文件。我們需要設置響應頭的Content-Disposition的key並且還要明確響應是多媒體類型。

public ResponseEntity<Object> downloadFile() throws IOException{
    String filename = "/var/tmp/mysql.png";
    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");
    header.add("Prama", "no-cache");
    header.add("Expires", "0");
}

完整代碼如下

    @RequestMapping(value = "/download", method = RequestMethod.GET)
    public ResponseEntity<Object> downFile() throws FileNotFoundException {
        String filename = "/var/tmp/aa.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 responseEntity = ResponseEntity.ok().headers(headers).contentLength(file.length()).
                contentType(MediaType.parseMediaType("application/txt")).body(resource);

        return responseEntity;
    }

關於更多Content-type的內容，請參考：這裏
也可以查看 org.springframework.util.MimeTypeUtils 類的常量

參考

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Spring Boot-File Handing