带有多部分文件上传的 Spring REST API 不适用于可选参数

Question

我正在使用 Spring 框架，但对它不太熟悉。我正在编写一个 REST API，特别是一个处理文件上传的 POST 方法，其中文件是可选的。

我已尝试简化方法，但仍有问题。这是我所拥有的

@RequestMapping(method = RequestMethod.POST, value="/items")
public String create(@RequestParam(value="file", required=false) MultipartFile file) {
    return "Create";
}

当我在表单请求中包含文件时，该方法可以正常工作，但是当我没有文件时（因为我希望它是可选的）。我尝试用HttpServletRequest 参数替换@RequestParam，得到相同的结果。

我收到以下堆栈跟踪的 500 错误：

java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: Stream ended unexpectedly
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre></p><p><b>root cause</b> <pre>org.springframework.web.multipart.MultipartException: Could not parse multipart servlet request; nested exception is java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: Stream ended unexpectedly
    org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.parseRequest(StandardMultipartHttpServletRequest.java:99)
    org.springframework.web.multipart.support.StandardMultipartHttpServletRequest.&lt;init&gt;(StandardMultipartHttpServletRequest.java:77)
    org.springframework.web.multipart.support.StandardServletMultipartResolver.resolveMultipart(StandardServletMultipartResolver.java:76)
    org.springframework.web.servlet.DispatcherServlet.checkMultipart(DispatcherServlet.java:1067)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:906)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:863)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre></p><p><b>root cause</b> <pre>java.io.IOException: org.apache.tomcat.util.http.fileupload.FileUploadException: Stream ended unexpectedly
    org.apache.catalina.connector.Request.parseParts(Request.java:2806)
    org.apache.catalina.connector.Request.parseParameters(Request.java:3096)
    org.apache.catalina.connector.Request.getParameter(Request.java:1145)
    org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:382)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre></p><p><b>root cause</b> <pre>org.apache.tomcat.util.http.fileupload.FileUploadException: Stream ended unexpectedly
    org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:311)
    org.apache.catalina.connector.Request.parseParts(Request.java:2737)
    org.apache.catalina.connector.Request.parseParameters(Request.java:3096)
    org.apache.catalina.connector.Request.getParameter(Request.java:1145)
    org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:382)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
</pre></p><p><b>root cause</b> <pre>org.apache.tomcat.util.http.fileupload.MultipartStream$MalformedStreamException: Stream ended unexpectedly
    org.apache.tomcat.util.http.fileupload.MultipartStream.readHeaders(MultipartStream.java:480)
    org.apache.tomcat.util.http.fileupload.FileUploadBase$FileItemIteratorImpl.findNextItem(FileUploadBase.java:889)
    org.apache.tomcat.util.http.fileupload.FileUploadBase$FileItemIteratorImpl.&lt;init&gt;(FileUploadBase.java:854)
    org.apache.tomcat.util.http.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:259)
    org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:283)
    org.apache.catalina.connector.Request.parseParts(Request.java:2737)
    org.apache.catalina.connector.Request.parseParameters(Request.java:3096)
    org.apache.catalina.connector.Request.getParameter(Request.java:1145)
    org.apache.catalina.connector.RequestFacade.getParameter(RequestFacade.java:382)
    org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:70)
    org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)

我在网络上的搜索中只找到了一篇文章，它谈到这可能是 Spring 中的一个错误。我已经被这个问题困扰了一段时间，非常感谢一些帮助。

谢谢

Answer 1

这是我最终得到的解决方案。

@RequestMapping(method = RequestMethod.POST, value = "/object")
ResponseEntity<Object> create(@RequestParam("is_file") boolean isFile, HttpServletRequest request) {
    if(isFile) {
      MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
      MultipartFile file = multipartRequest.getFile("file");
    } else{
      // You can add other parameters (as long as it isn't a multipart parameter) and do other stuff here
    }

}

Answer 2

我可以看到问题有点老了，但我把我的答案放在这里，因为上传文件主题总是存在的。 我在这个问题的上下文中测试了 Spring Boot 1.3.5.RELEASE。 我如下定义了休息服务，当文件未附加到多部分/表单数据时它可以工作。 我用 RestTemplate 客户端测试了服务。

@RequestMapping(method = RequestMethod.POST)
public ResponseEntity<String> upload(@RequestPart(value = "name", required = false) String name,
                                     @RequestPart(value = "file", required = false) MultipartFile file) 

Answer 3

我遇到了同样的问题，只是添加 required=false 对我有用。请在下面找到示例代码，

@RequestMapping(method = RequestMethod.POST, value="/items")
public String create(@RequestParam(value ="file", required=false) MultipartFile file) {
    return "Create";
}