Java Servlet Application with Maven | Generated by AI

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Here’s a complete guide to creating and deploying a simple Java Servlet application on WebSphere Liberty Profile (WLP) using Maven for building the project and the Liberty Maven plugin for deployment. This example creates a basic Servlet that returns “Hello World!” when accessed, builds it into a WAR file with Maven, and deploys it to WLP. We’ll assume you’ve already set up WLP with the servlet-4.0 feature enabled, as this provides the necessary Servlet support.

Step-by-Step Guide

1. Create the Maven Project Structure

Start by setting up a standard Maven web application structure. You can create this manually or use Maven to generate it.

2. Write the Servlet Code

Create a file named HelloServlet.java in src/main/java/com/example/ with the following content:

package com.example;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class HelloServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
        resp.setContentType("text/plain");
        resp.getWriter().write("Hello World!");
    }
}

3. Create the web.xml Deployment Descriptor

Create a file named web.xml in src/main/webapp/WEB-INF/ with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
         version="4.0">
    <servlet>
        <servlet-name>HelloServlet</servlet-name>
        <servlet-class>com.example.HelloServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>HelloServlet</servlet-name>
        <url-pattern>/hello</url-pattern>
    </servlet-mapping>
</web-app>

4. Configure the Maven pom.xml

Create or update pom.xml in the SimpleServletApp/ directory with the following content:

<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.example</groupId>
    <artifactId>simple-servlet-app</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
        <!-- Servlet API (provided by WLP) -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <!-- Maven WAR Plugin to build the WAR file -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.3.1</version>
                <configuration>
                    <finalName>myapp</finalName>
                </configuration>
            </plugin>
            <!-- Liberty Maven Plugin for deployment -->
            <plugin>
                <groupId>io.openliberty.tools</groupId>
                <artifactId>liberty-maven-plugin</artifactId>
                <version>3.3.4</version>
                <configuration>
                    <installDirectory>/opt/ibm/wlp</installDirectory>
                    <serverName>myServer</serverName>
                    <appsDirectory>dropins</appsDirectory>
                    <looseApplication>false</looseApplication>
                    <stripVersion>true</stripVersion>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

5. Build the Project

From the SimpleServletApp/ directory, build the WAR file using Maven:

mvn clean package

6. Deploy and Run on WebSphere Liberty

Ensure your Liberty server (myServer) is set up with the servlet-4.0 feature enabled. Check your server.xml for:

<featureManager>
    <feature>servlet-4.0</feature>
</featureManager>

Deploy and run the application using the Liberty Maven plugin:

mvn liberty:run

7. Access the Application

Open a browser and navigate to:

http://localhost:9080/myapp/hello

8. Stop the Server

Since mvn liberty:run runs the server in the foreground, stop it by pressing Ctrl+C in the terminal.

Notes

Summary

This guide demonstrates how to:

  1. Set up a Maven project with a simple Servlet (HelloServlet.java) and web.xml.
  2. Configure pom.xml with the Servlet API, Maven WAR plugin, and Liberty Maven plugin.
  3. Build the application into myapp.war using mvn clean package.
  4. Deploy and run it on WLP using mvn liberty:run.
  5. Access “Hello World!” at http://localhost:9080/myapp/hello.

This provides a streamlined, Maven-based approach to developing and deploying a Servlet application on WebSphere Liberty Profile.

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