java Spring 3.0 MultipartFile 上传

Spring 3.0 MultipartFile upload

提问by Gary

I am converting Java web application to Spring framework and appreciate some advice on the issues I am facing with the file upload. Original code was written using org.apache.commons.fileupload.

我正在将 Java Web 应用程序转换为 Spring 框架，并感谢有关我在上传文件时遇到的问题的一些建议。原始代码是使用 org.apache.commons.fileupload 编写的。

1. Does Spring MultipartFile wraps org.apache.commons.fileupload or I can exclude this dependency from my POM file?

2. I have seen following example:

   @RequestMapping(value = "/form", method = RequestMethod.POST)
   public String handleFormUpload(@RequestParam("file") MultipartFile file) {
   
       if (!file.isEmpty()) {
           byte[] bytes = file.getBytes();
           // store the bytes somewhere
          return "redirect:uploadSuccess";
       } else {
           return "redirect:uploadFailure";
       }
   }
   

   Originally I tried to follow this example but was always getting an error as it couldn't find this request param. So, in my controller I have done the following:

   @RequestMapping(value = "/upload", method = RequestMethod.POST)
   public @ResponseBody
   ExtResponse upload(HttpServletRequest request, HttpServletResponse response)
   {
      // Create a JSON response object.
      ExtResponse extResponse = new ExtResponse();
      try {
          if (request instanceof MultipartHttpServletRequest)
          {
              MultipartHttpServletRequest multipartRequest =
                           (MultipartHttpServletRequest) request;
              MultipartFile file = multipartRequest.getFiles("file");
              InputStream input = file.getInputStream();
              // do the input processing
              extResponse.setSuccess(true);
           }
       } catch (Exception e) {
           extResponse.setSuccess(false);
           extResponse.setMessage(e.getMessage());
       }
       return extResponse;
   }
   

1. Spring MultipartFile 是否包装 org.apache.commons.fileupload 或者我可以从我的 POM 文件中排除这个依赖项？

2. 我见过以下例子：

   @RequestMapping(value = "/form", method = RequestMethod.POST)
   public String handleFormUpload(@RequestParam("file") MultipartFile file) {
   
       if (!file.isEmpty()) {
           byte[] bytes = file.getBytes();
           // store the bytes somewhere
          return "redirect:uploadSuccess";
       } else {
           return "redirect:uploadFailure";
       }
   }
   

   最初我试图遵循这个例子，但总是收到错误，因为它找不到这个请求参数。因此，在我的控制器中，我完成了以下操作：

   @RequestMapping(value = "/upload", method = RequestMethod.POST)
   public @ResponseBody
   ExtResponse upload(HttpServletRequest request, HttpServletResponse response)
   {
      // Create a JSON response object.
      ExtResponse extResponse = new ExtResponse();
      try {
          if (request instanceof MultipartHttpServletRequest)
          {
              MultipartHttpServletRequest multipartRequest =
                           (MultipartHttpServletRequest) request;
              MultipartFile file = multipartRequest.getFiles("file");
              InputStream input = file.getInputStream();
              // do the input processing
              extResponse.setSuccess(true);
           }
       } catch (Exception e) {
           extResponse.setSuccess(false);
           extResponse.setMessage(e.getMessage());
       }
       return extResponse;
   }
   

and it is working. If someone can tell me why @RequestParam did not work for me, I will appreciate. BTW I do have

它正在工作。如果有人能告诉我为什么@RequestParam 对我不起作用，我将不胜感激。顺便说一句，我确实有

    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="maxUploadSize" value="2097152"/>
    </bean>

in my servlet context file.

在我的 servlet 上下文文件中。

回答by Bozho

1. spring does not have a dependency on commons-fileupload, so you'll need it. If it's not there spring will use its internal mechanism
2. You should pass a MultipartFileas a method parameter, rather than @RequestParam(..)

1. spring 不依赖于 commons-fileupload，因此您需要它。如果它不存在，弹簧将使用其内部机制
2. 您应该将 aMultipartFile作为方法参数传递，而不是@RequestParam(..)

回答by Surekha

I had to

我不得不

1. add commons-fileupload dependency to my pom,
2. add multipartResolver bean (mentioned in the question),
3. use @RequestParam("file") MultipartFile file in the handleFormUpload method and
4. add enctype in my jsp : <form:form method="POST" action="/form" enctype="multipart/form-data" >

1. 将 commons-fileupload 依赖项添加到我的 pom，
2. 添加 multipartResolver bean（在问题中提到），
3. 在 handleFormUpload 方法中使用 @RequestParam("file") MultipartFile 文件和
4. 在我的 jsp 中添加 enctype ： <form:form method="POST" action="/form" enctype="multipart/form-data" >

to get it to work.

让它工作。

回答by bobmanc

This works for me.

这对我有用。

@RequestMapping(value = "upload.spr", method = RequestMethod.POST)
public ModelAndView upload(@RequestParam("file") MultipartFile file, HttpServletResponse response)
{
    //  handle file here
}

回答by viquar

The General sysntax for request param is this @RequestParam(value="Your value", required=true), mode over request param is used to get a value frm the Url.

请求参数的通用 sysntax 是这个 @RequestParam(value="Your value", required=true)，请求参数的模式用于从 Url 获取值。

回答by killjoy

In a POST you will only send the params in the request body, not in the URL (for which you use @RequestParams)

在 POST 中，您只会在请求正文中发送参数，而不是在 URL 中（为此您使用 @RequestParams）

Thats why your second method worked.

这就是你的第二种方法奏效的原因。

回答by Mladen Uzelac

In Spring MVC 3.2 support for Servet 3.0 was introduced. So you need to include commons-file upload if you use earlier versions of Spring.

在 Spring MVC 3.2 中引入了对 Servet 3.0 的支持。因此，如果您使用 Spring 的早期版本，则需要包含 commons-file upload。