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我有以下方法来上传文件。当我inputStream从这MultipartFile一行file.getInputStream()得到一个 NullPointerException。

当我调试 MultipartFile 时，我得到以下信息

在此处输入图像描述

@PostMapping
public ResponseEntity<Void> fileUploadSave(@RequestPart(value = "file", required = true) MultipartFile file) {
    service.fileUploadSave(file);
    return new ResponseEntity<>(HttpStatus.OK);
}

private void fileUploadSave(MultipartFile file) {
    try {
        Path rootLocation = Paths.get(directory);
        if (!Files.exists(rootLocation)) {
            try {
                Files.createDirectories(Paths.get(directory));
            } catch (IOException e) {
                throw new RuntimeException("Could not create upload folder!");
            }
        }
        
        Path destinationFile = rootLocation.resolve(Paths.get(file.getOriginalFilename())).normalize().toAbsolutePath();
        if (!destinationFile.getParent().equals(rootLocation.toAbsolutePath())) {
            // This is a security check
            throw new RuntimeException("Cannot store file outside current directory.");
        }
        try (InputStream inputStream = file.getInputStream()) {
            Files.copy(inputStream, destinationFile, StandardCopyOption.REPLACE_EXISTING);
        }
        
    } catch (Exception e) {
        throw new RuntimeException("Failed to store file.", e);
    }
}

堆栈跟踪

Caused by: java.lang.NullPointerException: null
    at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.isInMemory(DiskFileItem.java:259)
    at org.apache.tomcat.util.http.fileupload.disk.DiskFileItem.getInputStream(DiskFileItem.java:193)
    at org.apache.catalina.core.ApplicationPart.getInputStream(ApplicationPart.java:100)
    at org.springframework.web.multipart.support.StandardMultipartHttpServletRequest$StandardMultipartFile.getInputStream(StandardMultipartHttpServletRequest.java:251)
    at com.entities.handlers.EstablishmentEntityManager.fileUploadSave(EstablishmentEntityManager.java:648)
    ... 24 common frames omitted
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