Java Tutorials Corner: JAX-RS QueryParam

In this tutorial we are going to see how to pass parameters to RESTful web service via URL using @QueryParam
1. Create new Dynamic web project by choosing File –> New –> Dynamic Web Project .

2. Create the Project called RESTful-WebService

3. Add the following jar into WEF-INF/lib folder

4. Create package called com.javatutorialscorner.jaxrs.queryparam under RESTful-WebService

5. Create Java class QueryParamService under com.javatutorialscorner.jaxrs.queryparam package

QueryParamService .java

package com.javatutorialscorner.jaxrs.queryparam;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Response;

@Path("/tutorials")
public class QueryParamService {

 @GET
 @Path("/java-tutorial")
 public Response getTutorial(@QueryParam("site") String site,
   @QueryParam("tutorial") String tutorial,
   @QueryParam("rank") int rank) {
  return Response
    .status(200)
    .entity("Web Site : " + site + "  Tutorial : " + tutorial
      + " Rank : " + rank).build();
 }
}

In above class @QueryParam used to get the value of URL query parameter into Java Class.

6.Configure Jersey Servlet Dispatcher

you need to configure REST as servlet in web.xml.
web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>JAX-RS-Path</display-name>
<servlet>
  <servlet-name>jersey-serlvet</servlet-name>
  <servlet-class>
                     com.sun.jersey.spi.container.servlet.ServletContainer
                </servlet-class>
  <init-param>
       <param-name>com.sun.jersey.config.property.packages</param-name>
       <param-value>com.javatutorialscorner.jaxrs.queryparam</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
 </servlet>
 
 <servlet-mapping>
  <servlet-name>jersey-serlvet</servlet-name>
  <url-pattern>/rest/*</url-pattern>
 </servlet-mapping>
</web-app>

The servlet class available in jersey com.sun.jersey.spi.container.servlet.ServletContainer. The init param com.sun.jersey.config.property.package is used to define in which package jersey will look for the service classes.This package points to your resource class package. URL pattern is the part of base URL

Now you can run the service and access the service by calling the following URL

http://localhost:8080/RESTful-WebService/rest/tutorials/java-tutorial?site=www.javatutorialscorner.com&tutorial=RESTful%20WebService&rank=1

In above URL, the query parameter site=www.javatutorialscorner.com is access by @QueryParam("site") annotation.If you are using query param two times it will converted into list for example tutorial=java&tutorial=stuts will be converted into java.util.List

you can call the service by using web browser or from client class.

Web browser call

Create Client

Create package called com.javatutorialscorner.jaxrs.client under RESTful-WebService project
Create Client Java Class RESTfulClient under com.javatutorialscorner.jaxrs.client package

RESTfulClient .java

package com.javatutorialscorner.jaxrs.client;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.ClientResponse;
import com.sun.jersey.api.client.WebResource;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;

public class RESTfulClient {

 /**
  * @param args
  */
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  String baseURI = "http://localhost:8080/RESTful-WebService";
  ClientConfig config = new DefaultClientConfig();
  Client client = Client.create(config);
  WebResource service = client.resource(baseURI);
  System.out.println("output for path param");
  System.out.println(service.path("rest").path("tutorials/java-tutorial")
    .queryParam("site", "www.javatutorialscorner.com")
    .queryParam("tutorial", "RESTful WebService")
    .queryParam("rank", "1").get(ClientResponse.class)
    .getEntity(String.class));
 }

}