Spring REST MultipartFile file is always null

file-upload, java, model-view-controller, rest, spring

Solution

As I remember I solved same issue by putting additional libs to my build path:

commons-fileupload-1.2.2.jar
commons-io-2.1.jar

I hope this will help you.

Edit.

Ok. At last I had time for this issue. First of all, why do you use standart java features for building rest service (annotations @POST, @Path)? Because with Spring it is better to use spring MVC futures for REST. There is a lot of information about this in internet. Here is special part in reference documentation. Also here is good article on IBM site. Also very good description on how to build REST controller with Spring MVC is in Spring in Action (last 3-d edition).

Here how I have implemented simple file uploading functionality:

Rest controller:

@Controller
@RequestMapping("/rest/files")
public class FilesController {
        ...

        @RequestMapping(value="/rest/files", method=RequestMethod.POST)
        public String uploadFile(@RequestParam("name") String name,
                @RequestParam("file") MultipartFile file) {
            try {
                if (!file.isEmpty()) {
                    byte[] bytes = file.getBytes();
                    // store the bytes somewhere
                    return "redirect:uploadSuccess";
                } else {
                    return "redirect:uploadFailure";
                }
            }
            catch (Exception ex)
            {

            }
            return "/testFileDownload";
        }
}

html:

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Test file upload</title>
</head>
<body>
    <h1>Please upload a file</h1>
    <form method="post" action="rest/files" enctype="multipart/form-data">
        <input type="text" name="name" /> <input type="file" name="file" /> <input
            type="submit" />
    </form>
</body>
</html>

View resolver configuration in dispatcher-servlet.xml:

<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
        <property name="mediaTypes">
            <map>
                <entry key="file" value="multipart/form-data"/>
                <entry key="html" value="text/html"/>
            </map>
        </property>
        <property name="viewResolvers">
            <list>
                <bean class="org.springframework.web.servlet.view.BeanNameViewResolver"/>
                <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
                    <property name="prefix" value="/WEB-INF/views/"/>
                    <property name="suffix" value=".jsp"/>
                </bean>
            </list>
        </property>
    </bean>

I hope I'm not wasted my time and this is still necessary for you. )

EDIT 2

Here is very good tutorial where described how to build RESTful web service with Spring 3.1.

Problem

I'm trying to set up a simple upload with html and Spring 3.0.6 using REST services. I've followed the tutorial online but the MultipartFile parameter is always null. Here's the config and code: application-context.xml: ``` <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <property name="maxUploadSize" value="2000000"/> </bean> ``` pom.xml: ``` <dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.1</version> </dependency> <dependency> <groupId>commons-fileupload</groupId> <artifactId>commons-fileupload</artifactId> <version>1.2.2</version> </dependency> ``` html: ``` <html> <head> <title>Upload a file please</title> </head> <body> <h1>Please upload a file</h1> <form method="post" action="/site/restServices/artworkUpload/" enctype="multipart/form-data"> <input type="text" name="name"/> <input type="file" name="file"/> <input type="submit"/> </form> </body> </html> ``` REST Controller: ``` @POST @Path("/artworkUpload") public String uploadFile(@RequestParam("name") String name, @RequestParam("file") MultipartFile file) { try { if (!file.isEmpty()) { byte[] bytes = file.getBytes(); // store the bytes somewhere return "redirect:uploadSuccess"; } else { return "redirect:uploadFailure"; } } catch (Exception ex) { } return null; } ``` I copied the example from Spring's tutorial but no matter what I change, the file parameter is always null. "name" will have the value in the text box but file will be null. I have also tried using Jersey and I receive the InputStream for the file but the FormDataContentDisposition is null so I can't determine the file type. This is running on Jetty as well. What am I missing?

Original source