Spring configuration for a JSON/XML REST service in Java

In Creating a CXF service that responds with JSON or XML and Creating a CXF client which can get JSON or XML we created a service and a client application for interacting with REST requests using XML or JSON as the body for the messages.

The Java guys love spring and beans, my code was all in Java source. So I’m going to show how to convert both the server and client into spring configurations.

In your client/server code add a resources folder to /src/main and within that add a new xml file, named whatever you like, mine’s spring-client.xml and spring-server.xml (for the client and server respectively).

Changes to the server

Let’s concentrate on the server first – our code looked like this

JAXRSServerFactoryBean factoryBean = new JAXRSServerFactoryBean();
factoryBean.setResourceClasses(SampleServiceImpl.class);
factoryBean.setResourceProvider(new SingletonResourceProvider(new SampleServiceImpl()));

Map<Object, Object> extensionMappings = new HashMap<Object, Object>();
extensionMappings.put("xml", MediaType.APPLICATION_XML);
extensionMappings.put("json", MediaType.APPLICATION_JSON);
factoryBean.setExtensionMappings(extensionMappings);

List<Object> providers = new ArrayList<Object>();
providers.add(new JAXBElementProvider());
providers.add(new JacksonJsonProvider());
factoryBean.setProviders(providers);

factoryBean.setAddress("http://localhost:9000/");
Server server = factoryBean.create();

The first thing we need to do is update our pom.xml to import spring, so add the following to the properties section

<spring.version>2.5.6</spring.version>

and then these dependencies

<dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-context</artifactId>
   <version>${spring.version}</version>
</dependency>

<dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-core</artifactId>
   <version>${spring.version}</version>
</dependency>

Now change the Java code in our main method, replacing all the code which is listed above, to 

ApplicationContext context = new ClassPathXmlApplicationContext("spring-server.xml");

Now we need to add the following to our spring-server.xml file

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:jaxrs="http://cxf.apache.org/jaxrs"
       xsi:schemaLocation="
         http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
         http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd">

    <jaxrs:server address="http://localhost:9000">
        <jaxrs:serviceBeans>
            <bean class="SampleServiceImpl" />
        </jaxrs:serviceBeans>
        <jaxrs:extensionMappings>
            <entry key="json" value="application/json"/>
            <entry key="xml" value="application/xml"/>
        </jaxrs:extensionMappings>
        <jaxrs:providers>
            <bean class="org.apache.cxf.jaxrs.provider.JAXBElementProvider" />
            <bean class="org.codehaus.jackson.jaxrs.JacksonJsonProvider" />
        </jaxrs:providers>
    </jaxrs:server>
</beans>

We’re using the jaxrs configuration to create our service beans which means the server is automatically created for us.

That’s it for the server.

Changes to the client

Let’s look at the existing client code

List<Object> providers = new ArrayList<Object>();
providers.add(new JAXBElementProvider());
providers.add(new JacksonJsonProvider());

SampleService service = JAXRSClientFactory.create(
   "http://localhost:9000", SampleService.class, providers);

WebClient.client(service)
   .type(MediaType.APPLICATION_JSON_TYPE)
   .accept(MediaType.APPLICATION_JSON_TYPE);

First off, we need to add spring to the pom.xml as we needed for the server, so duplicate the steps for updating the pom.xml as already outlined.

Next we replace our client code (above) with the following

ApplicationContext context = new ClassPathXmlApplicationContext("spring-client.xml");
SampleService service = (SampleService)context.getBean("client");

and finally put the following into the spring-client.xml file

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:jaxrs="http://cxf.apache.org/jaxrs"
       xsi:schemaLocation="
         http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
         http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd">

    <jaxrs:client id="client" address="http://localhost:9000" serviceClass="SampleService">
        <jaxrs:providers>
            <bean class="org.apache.cxf.jaxrs.provider.JAXBElementProvider" />
            <bean class="org.codehaus.jackson.jaxrs.JacksonJsonProvider" />
        </jaxrs:providers>
        <jaxrs:headers>
            <entry key="Accept" value="application/json" />
        </jaxrs:headers>
    </jaxrs:client>
</beans>

and that’s it – run the server, then run the client and all should work.

Note: I’ll leave it to the reader to add the relevant import statements