Hello World with Java Servlet and JSP (Easy web server startup with Maven + Jetty)

Overview

--Run Java Servlet and JSP in local environment --Use Jetty for Servlet container --Launch Jetty with Maven plugin

environment

macOS Mojave
OpenJDK 11.0.2
Apache Maven 3.6.1
Jetty 9.4.19.v20190610 (Servlet API 3.1, JSP 2.3)

Source code

Source code list

--pom.xml: Build config file for Maven --MyServlet.java: Java Servlet source code --index.jsp: JSP source code --web.xml: Web application configuration file

├── pom.xml
└── src
    └── main
        ├── java
        │   └── com
        │       └── example
        │           └── MyServlet.java
        └── webapp
            ├── WEB-INF
            │   └── web.xml
            └── index.jsp

pom.xml: Build config file for Maven

--Add javax.servlet-api to dependency to use Java Servlet API 3.1. --Add jetty-maven-plugin so that you can easily start Jetty from Maven and check the operation.

<?xml version="1.0" encoding="UTF-8"?>

<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>my-servlet</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>war</packaging>
  <name>my-servlet</name>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>11</maven.compiler.source>
    <maven.compiler.target>11</maven.compiler.target>
    <jetty.version>9.4.19.v20190610</jetty.version>
  </properties>

  <dependencies>
    <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <!-- https://www.eclipse.org/jetty/documentation/current/jetty-maven-plugin.html -->
      <plugin>
        <groupId>org.eclipse.jetty</groupId>
        <artifactId>jetty-maven-plugin</artifactId>
        <version>${jetty.version}</version>
      </plugin>
    </plugins>
  </build>

</project>

MyServlet.java: Java Servlet source code

package com.example;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;

public class MyServlet extends HttpServlet {

  @Override
  protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    resp.setContentType("text/html; charset=utf-8");
    PrintWriter out = resp.getWriter();
    out.println("<html><body>Hello, Servlet World!</body></html>");
    out.flush();
    out.close();
  }
}

index.jsp: JSP source code

<html><body>Hello JSP World!</body></html>

web.xml: web application configuration file

--Mapping the Servlet of MyServlet.java so that it can be accessed with / my-servlet / *.

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>My Servlet Web Application</display-name>

  <servlet>
    <servlet-name>MyServlet</servlet-name>
    <servlet-class>com.example.MyServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>MyServlet</servlet-name>
    <url-pattern>/my-servlet/*</url-pattern>
  </servlet-mapping>
</web-app>

Launch Jetty to access your web application

You can start Jetty with mvn jetty: run.

$ mvn jetty:run

When you access http: // localhost: 8080 / my-servlet /, the content output by MyServlet.java is returned.

$ curl http://localhost:8080/my-servlet/
<html><body>Hello, Servlet World!</body></html>

When you access http: // localhost: 8080 /, the content written in index.jsp is returned.

$ curl http://localhost:8080/
<html><body>Hello JSP World!</body></html>