Jersey 2 injection source for multipart formdata

You need to enable MultiPart feature on your application. Enabling this feature injects necessary message body readers, writers to your Jersey 2 application. Here is how you register them:

On the server-side (http-server):

final ResourceConfig resourceConfig = new ResourceConfig(MultiPartResource.class);
resourceConfig.register(MultiPartFeature.class);

On the server-side (servlet deployment):

import org.glassfish.jersey.filter.LoggingFilter;
import org.glassfish.jersey.media.multipart.MultiPartFeature;

import javax.ws.rs.core.Application;
import java.util.HashSet;
import java.util.Set;

public class MyApplication extends Application {
    @Override
    public Set<Class<?>> getClasses() {
        final Set<Class<?>> classes = new HashSet<Class<?>>();
        // register resources and features
        classes.add(MultiPartFeature.class);
        classes.add(MultiPartResource.class);
        classes.add(LoggingFilter.class);
        return classes;
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
    <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <servlet>
        <servlet-name>Jersey Servlet</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
        <init-param>
            <param-name>javax.ws.rs.Application</param-name>
            <param-value>com.aruld.jersey.multipart.MyApplication</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Jersey Servlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

On the client-side:

final ClientConfig clientConfig = new ClientConfig();
clientConfig.register(MultiPartFeature.class);
Client client = ClientFactory.newClient(clientConfig);

I put together an end-to-end Jersey 2 MultiPart sample in Github here.