http://opensourcesoftwareandme.blogspot.hk/2012/12/demystifying-apache-cxf-restful-hello.html
The
first post of this how-to series showed you what it takes to expose a Hello World application as a SOAP over HTTP Web Service using CXF. For this post, I'll show you how to expose the same
app as a RESTful service.
In the Java world, we use JAX-RS for mapping a class to a RESTful service. Giving a RESTful interface to our Hello World app is just a matter of adding JAX-RS annotations to
HelloWorldImpl:
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package org.opensourcesoftwareandme;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
@Path("/helloWorld")
public class HelloWorldImpl {
@GET
@Produces("text/html")
@Path("sayHi/{text}")
public String sayHi(@PathParam("text") String text) {
return "Hello " + text;
}
}
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In the class, I tell the JAX-RS provider (i.e., CXF):
- HelloWorldImpl is a resource available on the URL relative path "/helloWorld" (@Path("/helloWorld")).
- the HTTP reply sent back to the client should have the Content-Type set to "text/hml" (@Produces).
- sayHi is to be called when the HTTP request is a GET and the relative path is "/helloWorld/sayHi/" + [variable] (@Path("sayHi/{text}")).
- to bind the URL parameter with the method argument text (@PathParam).
As in the previous how-to, I'm going to deploy the app onto an embedded Jetty server instead of deploying it onto a standalone web container:
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package org.opensourcesoftwareandme;
import org.apache.cxf.jaxrs.JAXRSServerFactoryBean;
import javax.ws.rs.ext.RuntimeDelegate;
public class Server {
public static void main(String args[]) throws Exception {
JAXRSServerFactoryBean jaxrsServerFactory = RuntimeDelegate.getInstance().createEndpoint(new HelloWorldApp(), JAXRSServerFactoryBean.class);
jaxrsServerFactory.setAddress("http://localhost:9000");
org.apache.cxf.endpoint.Server server = jaxrsServerFactory.create();
server.start();
System.out.println("Server started...");
Thread.sleep(5 * 60 * 1000);
System.out.println("Server stopping...");
server.stop();
System.exit(0);
}
}
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RuntimeDelegate.getInstance().createEndpoint(...) is a JAX-RS method that returns an unpublished endpoint. It takes in:
- a class responsible for configuring and launching the web server. This class differs across JAX-RS providers. CXF expects this class to be JAXRSServerFactoryBean.
- an object that extends Application. This user-defined class must return JAX-RS annotated classes responsible for processing client requests. For us, this means returning HelloWorldImpl:
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package org.opensourcesoftwareandme;
import javax.ws.rs.core.Application;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
public class HelloWorldApp extends Application {
public Set<Class<?>> getClasses() {
Set<Class<?>> classes = new HashSet<Class<?>>();
classes.add(HelloWorldImpl.class);
return classes;
}
}
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Before testing the service, I add the required CXF libraries to the Java classpath by declaring them as dependencies in project's POM :
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...
<dependencies>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-frontend-jaxrs</artifactId>
<version>${cxf.version}</version>
</dependency>
<dependency>
<groupId>org.apache.cxf</groupId>
<artifactId>cxf-rt-transports-http-jetty</artifactId>
<version>${cxf.version}</version>
</dependency>
</dependencies>
...
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If you compare this POM with the
POM of the first how-to, you'll note that now I've swapped the JAX-WS frontend with the JAX-RS one.
All that is left is to run the server with the following Maven commands:
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mvn package; mvn exec:java -Dexec.mainClass="org.opensourcesoftwareandme.Server"
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Once the server is up, accessing via your browser the URL http://localhost:9000/helloWorld/sayHi/Ricston should give you "Hello Ricston".