MultipartForm handling with Spring

问题:

This code is a RestEasy code for handling upload:

@Path("/fileupload")
public class UploadService {
    @POST
    @Path("/upload")
    @Consumes("multipart/form-data")
    public Response create(@MultipartForm FileUploadForm form) 
    {
       // Handle form
    }
}

Is there anything similar using Spring that can handle MultipartForm just like this?

回答1:

Spring includes has a multipartresolver that relies on commons-fileupload, so to use it you have to include it in your build.

In your applicationContext.xml

<bean id="multipartResolver"
    class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- one of the properties available; the maximum file size in bytes -->
    <property name="maxUploadSize" value="<max file size>"/>
</bean>

In your controller, use org.springframework.web.multipart.MultipartFile.

@RequestMapping(method=RequestMethod.POST, value="/multipartexample")
public String examplePost(@RequestParam("fileUpload") MultipartFile file){
    // Handle form upload and return a view
    // ...
}

回答2:

Here is an example showing how you could use MVC Annotations to achieve something similar in Spring:

@RequestMapping(method=RequestMethod.POST, value="/multipartexample")
public String examplePost(@ModelAttribute("fileUpload") FileUpload fileUpload){
    // Handle form upload and return a view
    // ...
}

@InitBinder
public void initBinder(ServletRequestDataBinder binder) {
    binder.registerCustomEditor(byte[].class, new ByteArrayMultipartFileEditor());
}

public class FileUpload implements Serializable {
    private MultipartFile myFile;

    public MultipartFile getMyFile() {
        return myFile;
    }

    public void setMyFile(MultipartFile myFile) {
        this.myFile = myFile;
    }
}

You should be able to post to this endpoint from the html form, assuming the name of the file element is 'myFile'. Your form could look like the following:

<form:form commandName="fileUpload" id="fileUploadForm" enctype="multipart/form-data">
    <form:input type="file" path="myFile" id="myFile"/>
</form:form>

The @InitBinder code is important because it instructs Spring to convert the files to a byte array, which can then be turned into the MultipartFile