JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Restful web services using RESTEasy hello world example.


In this page we are giving simple hello world restful web service example using RESTEasy framework. RESTEasy is JBOSS provided implementation of JAX-RS specification to build java based restful web service.

Here is the directory structure:

We need resteasy related jar files, here is the pom.xml file:

<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>RestfulWebServices</groupId>
  <artifactId>RestfulWebServices</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <dependencies>
  	<dependency>
  		<groupId>org.jboss.resteasy</groupId>
  		<artifactId>resteasy-jaxrs</artifactId>
  		<version>2.3.7.Final</version>
  	</dependency>
  </dependencies>
</project>

Simple service class with @Path annotations, you will get more details about these annotations going ahead in this site.

package com.java2novice.restful;

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

@Path("/publish")
public class RestEasyExample {

	@GET
	@Path("/{message}")
	public Response publishMessage(@PathParam("message") String msgStr){
		
		String responseStr = "Received message: "+msgStr;
		return Response.status(200).entity(responseStr).build();
	}
}

We need to configure resteasy within our web.xml file. We should set “resteasy.scan” to true, so that RESTEasy will find and register your REST service by default. Here is the web.xml file for your reference:

<web-app id="WebApp_ID" version="2.4"
	xmlns="http://java.sun.com/xml/ns/j2ee" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
	http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	
    <!-- Auto scan REST service -->
    <context-param>
        <param-name>resteasy.scan</param-name>
        <param-value>true</param-value>
    </context-param>
    
    <listener>
		<listener-class>
			org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
		</listener-class>
	</listener>
    
    <servlet>
        <servlet-name>resteasy-servlet</servlet-name>
        <servlet-class>
            org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
        </servlet-class>
    </servlet>
  
    <servlet-mapping>
        <servlet-name>resteasy-servlet</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
</web-app>

Now create war file and deploy it either in tomcat or jboss. Run the server and open link http://localhost:8080/RestfulWebServices/publish/{user-input} in the browser. Here {user-input} value can be dynamic, this value will be received by the rest service and returns as a response:

 Next Program >>

Restful Web Services Examples

  1. Restful web services using RESTEasy hello world example.
  2. Restful web services using Jersey hello world example.
  3. JAX-RS @Path annotation example
  4. JAX-RS @Path annotation with regular expression match example
  5. JAX-RS @PathParam annotation example
  6. JAX-RS @QueryParam and @DefaultValue annotations example
  7. JAX-RS @MatrixParam annotation example
  8. How to read multiple values of a query paramter in JAX-RS restful web services?
  9. How to pass header parameters as method inputs in JAX-RS restful web services?
  10. How to read header parameters in JAX-RS restful web services?
  11. JAX-RS @FormParam annotation example
  12. How to upload file using Jersey restful web services?
  13. How to download file using java restful web services?
  14. XML based Restful web service with RESTEasy and JAXB.
  15. XML based Restful web service with Jersey and JAXB.
  16. Json based Restful web service with RESTEasy, Jettison and JAXB
  17. Json based Restful web service with RESTEasy and Jackson
  18. Json based Restful web service with Jersey and Jackson
  19. How to input json request with Jersey and Jackson?
  20. Java client for restful web service using java.net package
  21. Java client for restful web service using Jersey API
  22. Java restful webservices with HTTP basic authentication.
Knowledge Centre
When to use LinkedList or ArrayList?
Accessing elements are faster with ArrayList, because it is index based. But accessing is difficult with LinkedList. It is slow access. This is to access any element, you need to navigate through the elements one by one. But insertion and deletion is much faster with LinkedList, because if you know the node, just change the pointers before or after nodes. Insertion and deletion is slow with ArrayList, this is because, during these operations ArrayList need to adjust the indexes according to deletion or insetion if you are performing on middle indexes. Means, an ArrayList having 10 elements, if you are inserting at index 5, then you need to shift the indexes above 5 to one more.
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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