Jersey – RESTful service

原文地址：http://techannotation.wordpress.com/2012/05/30/jersey-restful-service/

In one of my project, I used a Jersey framework to build a REST application. In this post I’ll introduce this lightweight framework that implements JAX-RS (JSR 311) references. If you are familiar with Spring MVC Rest you’ll find it very similar (obviously
because both implement JAX-RS ).

First, we need the Jersey libraries to include.

We can include it inside 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"> <context-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:spring-easyrec.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>Jersey</servlet-name>
<servlet-class>com.sun.jersey.spi.spring.container.servlet.SpringServlet</servlet-class>
<init-param>
<param-name>com.sun.jersey.config.property.packages</param-name>
<param-value>it.sample.rest</param-value>
</init-param>
<init-param>
<param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
<param-value>it.sample.filter.UserExtractionFilter</param-value>
</init-param>
<init-param>
<param-name>com.sun.jersey.spi.container.ContainerResponseFilters</param-name>
<param-value>it.sample.filter.UserSetFilter</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>Jersey</servlet-name>
<url-pattern>/*</url-pattern>
</servlet-mapping>

</web-app>

The value of “com.sun.jersey.config.property.packages” is the java package that will be scanning for the rest annotation.

The value of “com.sun.jersey.spi.container.ContainerRequestFilters” is the class that implements com.sun.jersey.spi.container.ContainerRequestFilter interface. The only method that must be override is filter. This method will be invoked as first action at
your request.

package it.sample.filter;
import com.sun.jersey.spi.container.ContainerRequest;
import com.sun.jersey.spi.container.ContainerRequestFilter;
public class UserExtractionFilter implements ContainerRequestFilter {

@Override
public ContainerRequest filter(ContainerRequest request) {
// Before Request processed
return request;
}
}

Now we have to define the controller for our path. This controller used an annotation like Spring MVC. In the follow example we can see a controller class with annotation for accept request at the url /sample/json/order/{orderid} and

package it.sample.rest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.CookieParam;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.UriInfo;
import com.sun.jersey.api.json.JSONWithPadding;
@Path("sample")
@Produces("application/javascript")
public class ToDelete {

@Context
HttpServletResponse response = null;

@CookieParam("OrderCookie")
javax.ws.rs.core.Cookie orderCookie = null;

@Context
UriInfo info = null;

@GET
@Path("/order/json/{orderid}")
public JSONWithPadding orderProcessJson(@PathParam("orderid") String orderId)
{
return new JSONWithPadding("Processed!", "callback");
}

@GET
@Path("/order/xml/{orderid}")
@Produces("application/xml")
public JaxbOrder orderProcessXml(@PathParam("orderid") String orderId)
{
JaxbOrder jax = new JaxbOrder(orderId);
return jax;
}
}

The JaxbOrder class is jaxb annotated class. When the client invoke the method “orderProcessXml” it will be serialized in xml.

In conclusion I think Jersey is a good alternative of Spring MVC and it’s still my first choice when I have to take decision how to build a RESTful service.

You can find more information at official Jersey web site http://jersey.java.net/