JAX-RS @PathParam Example

Published by Mukesh Kumar

In JAX-RS @Path is used on method level to determinate the URI path to which the method responds.@PathParam is used to retrieve the value of an URI path variable. In other words you can use @PathParem to inject the value of URI parameter that defined in @Path expression, into method input parameters.

In this example, we will see how to use @PathParam in method arguments of a JAX-RS RESTful webservices.

1. Technologies used

• Maven
• Jersey 1.9
• Tomcat
• Eclipse
• JDK

Follow the steps mentioned below to develop the project.

Step 1 : Create Web Application Project using Maven Template

Create a Java web application project from maven-archetype-webapp template.

mvn archetype:generate -DgroupId=com.jwt.rest -DartifactId=RESTPathParamDemo -DarchetypeArtifactId=maven-archetype-webapp -DinteractiveMode=false

Step 2 : Eclipse IDE integration

Convert this project to Eclipse web project with Maven command "mvn eclipse:eclipse -Dwtpversion=1.5".Open command prompt and navigate to generated "RESTPathParamDemo" project and issue following command.

mvn eclipse:eclipse -Dwtpversion=1.5

Step 3 : Import the Project into eclipse

Import the project into eclipse IDE.

Step 4 : Update pom.xml file

Add the jersey dependencies in pom.xml.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.jwt.rest</groupId>
	<artifactId>RESTPathParamDemo</artifactId>
	<packaging>war</packaging>
	<version>1.0-SNAPSHOT</version>
	<name>RESTPathParamDemo Maven Webapp</name>
	<url>http://maven.apache.org</url>
	<dependencies>

		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-server</artifactId>
			<version>1.9</version>
		</dependency>

		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-servlet</artifactId>
			<version>1.19</version>
		</dependency>

		<dependency>
			<groupId>javax.ws.rs</groupId>
			<artifactId>jsr311-api</artifactId>
			<version>1.1.1</version>
		</dependency>
		<dependency>
			<groupId>com.sun.jersey</groupId>
			<artifactId>jersey-client</artifactId>
			<version>1.9</version>
		</dependency>
	</dependencies>
	<build>
		<finalName>RESTPathParamDemo</finalName>
	</build>
</project>

After updating the pom.xml again execute "mvn eclipse:eclipse -Dwtpversion=1.5". After executing this command Maven will download required libraries.

Note:- After above step refresh your project otherwise eclipse will not recognize the downloaded files.

Step 5 : Create Java directory :

Create a directory named java under main."/src/main". Right click on the project then select New ->Folder and provide the name as "java" as shown below.

Now add this directory to class path of your project.

Step 6 : Add java directory to classpath of the Project :

• Right click on Project -> Build Path -> Configure build path , a new screen will open in that screen click on Source tab and then click on Add folder as shown bellow.







• Again one new screen will open and in that screen select the java checkbox and click on OK button as shown bellow.








Now Java folder is in classpath of your project.

Step 7 : Create Web.xml configuration File

Specify Jersey framework Servlet for our application in web.xml file.In web.xml, register "com.sun.jersey.spi.container.servlet.ServletContainer", and puts your Jersey service folder under "init-param","com.sun.jersey.config.property.packages".

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_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>RESTfulExample</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.jwt.rest</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>

As you can see our servlet is mapped to /rest/ URI pattern. So the basic structure of the URIs used in this example will have the form :

http://localhost:8080/RESTPathParamDemo/rest/....

1 . Using @PathParam with single parameter

We will use @PathParam to parse a single URI parameter and retrieve the value of the name variable and set it into the name argument.

CompanyService.java

package com.jwt.rest;

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

@Path("/users")
public class UserRestService {
 
    // Single Parameter
    @GET
    @Path("{name}")
    public Response getUserByName(@PathParam("name") String name) {
        return Response.status(200).entity("getUserByName() method called, user name returned is  " + name + "]").build();
    }
 
}

In the above class ,Using @Path("{name}") we defined a new path parameter with name "name". After that we used @PathParam("name") to parse the value and push it to String "name" argument.

Run the application :

Right click on project -> run as -> run on server Select Apache tomcat and click on finish.

Access your page by typing following URL

http://localhost:8080/RESTPathParamDemo/rest/users/mukesh

Output :

2 . Using @PathParam with multiple parameters

Below is example to inject multiple parameters into Java method.

package com.jwt.rest;

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

@Path("/employee")
public class EmployeeService {
	@GET
	@Path("{empID}/{branch}/{department}")
	public Response getEmployeeList(@PathParam("empID") String empID,
			@PathParam("branch") String branchName,
			@PathParam("department") String deptName) {

		String resp = "Employee ID is  " + empID
				+ " department is " + deptName + " and Branch name is " +branchName;
		return Response.status(200).entity(resp).build();
	}
}

Now access the page by typing following URL

http://localhost:8080/RESTPathParamDemo/rest/employee/102/chennai/manufacturing

Output :

References :- JAX-RS Documentation

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