RESTFul Web Service Example with Jersey 2 and Tomcat 8

Jersey RESTful Web Services framework is open source, production quality, framework for developing RESTful Web Services in Java that provides support for JAX-RS APIs and serves as a JAX-RS (JSR 311 & JSR 339) Reference Implementation.

Let’s make an RESTFul web service example with Jersey 2 and Tomcat 8. Our web service is taking a word as parameter, reverse it and return that reversed word as response.

This is how Package Explorer is going to look like:

Follow File > New > Dynamic Web Project to create project in Eclipse.

Do not forget to check box “Generate web.xml deployment descriptor” in last page of setup wizard because we need web.xml file.

Right click project > Configure > Convert to Maven Project.

Right click project > Properties > Java Build Path add

javax.ws.rs-api-2.0.1 (comes with Jersey, find in jersey/api folder)

json-20151123 (can be downloaded from here)

We also going to add dependencies in pom.xml for these two.

In web.xml we define a rule about URLs which match with “/reverser/*” pattern is routed to “com.rest.jersey2” package.

<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>RestWithJersey2</groupId>
	<artifactId>RestWithJersey2</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
	<dependencies>
		<dependency>
			<groupId>org.glassfish.jersey.containers</groupId>
			<artifactId>jersey-container-servlet</artifactId>
			<version>2.22.1</version>
		</dependency>
		<dependency>
			<groupId>org.json</groupId>
			<artifactId>json</artifactId>
			<version>20151123</version>
		</dependency>
	</dependencies>
	<build>
		<sourceDirectory>src</sourceDirectory>
		<plugins>
			<plugin>
				<artifactId>maven-compiler-plugin</artifactId>
				<version>3.3</version>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
				</configuration>
			</plugin>
			<plugin>
				<artifactId>maven-war-plugin</artifactId>
				<version>2.6</version>
				<configuration>
					<warSourceDirectory>WebContent</warSourceDirectory>
					<failOnMissingWebXml>false</failOnMissingWebXml>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 	xmlns="http://xmlns.jcp.org/xml/ns/javaee" 	xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" 	id="WebApp_ID" version="3.1">
	<display-name>RestWithJersey2</display-name>
	<welcome-file-list>
		<welcome-file>index.html</welcome-file>
		<welcome-file>index.htm</welcome-file>
		<welcome-file>index.jsp</welcome-file>
		<welcome-file>default.html</welcome-file>
		<welcome-file>default.htm</welcome-file>
		<welcome-file>default.jsp</welcome-file>
	</welcome-file-list>

	<servlet>
		<servlet-name>Rest With Jersey2</servlet-name>
		<servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
		<init-param>
			<param-name>jersey.config.server.provider.packages</param-name>
			<param-value>com.rest.jersey2</param-value>
		</init-param>
		<load-on-startup>1</load-on-startup>
	</servlet>
	<servlet-mapping>
		<servlet-name>Rest With Jersey2</servlet-name>
		<url-pattern>/reverser/*</url-pattern>
	</servlet-mapping>
</web-app>

package com.rest.jersey2;

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.Response;

import org.json.JSONException;
import org.json.JSONObject;

@Path("/jsonbasedreverser")
public class JSONBasedReverser {

	@GET
	@Produces("application/json")
	public Response defaultReverser() throws JSONException {

		StringBuilder sb = new StringBuilder();
		sb.append("ANKARA");

		JSONObject jsonObject = new JSONObject();
		jsonObject.put("original", sb.toString());
		jsonObject.put("reversed", sb.reverse().toString());

		String result = "" + jsonObject;
		return Response.status(200).entity(result).build();
	}

	@Path("{word}")
	@GET
	@Produces("application/json")
	public Response reverser(@PathParam("word") String word) throws JSONException {

		StringBuilder sb = new StringBuilder();
		sb.append(word);

		JSONObject jsonObject = new JSONObject();
		jsonObject.put("original", sb.toString());
		jsonObject.put("reversed", sb.reverse().toString());

		String result = "" + jsonObject;
		return Response.status(200).entity(result).build();
	}

}

package com.rest.jersey2;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;

@Path("/xmlbasedreverser")
public class XMLBasedReverser {
	@GET
	@Produces("application/xml")
	public String defaultReverser() {

		StringBuilder sb = new StringBuilder();
		sb.append("ANKARA");

		return "<word>" + "<original>" + sb.toString() + "</original>" + "<reversed>" + sb.reverse().toString()
				+ "</reversed>" + "</word>";
	}

	@Path("{word}")
	@GET
	@Produces("application/xml")
	public String reverser(@PathParam("word") String word) {
		StringBuilder sb = new StringBuilder();
		sb.append(word);

		return "<word>" + "<original>" + sb.toString() + "</original>" + "<reversed>" + sb.reverse().toString()
				+ "</reversed>" + "</word>";
	}

}

Ready to build and deploy.

Go to:

http://localhost:8080/RestWithJersey2-0.0.1-SNAPSHOT/reverser/jsonbasedreverser

http://localhost:8080/RestWithJersey2-0.0.1-SNAPSHOT/reverser/jsonbasedreverser/istanbul

http://localhost:8080/RestWithJersey2-0.0.1-SNAPSHOT/reverser/xmlbasedreverser

http://localhost:8080/RestWithJersey2-0.0.1-SNAPSHOT/reverser/xmlbasedreverser/istanbul

Resources:

[1] http://crunchify.com/how-to-build-restful-service-with-java-using-jax-rs-and-jersey/

[2] https://wolfpaulus.com/journal/java-journal/jersey/

[3] http://tutorial-academy.com/restful-webservice-jersey-maven/

[4] http://stackoverflow.com/questions/18086218/java-lang-classnotfoundexception-com-sun-jersey-spi-container-servlet-servletco

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