Gradle easily supports Java web applications through the “war” and “jetty” plugins. This tutorial will show you how to quickly make a simple Java Servlet web application.
Our basic project structure will be:
basic-web
src
main
java
com
codetutr
HelloWorldServlet.java
webapp
WEB-INF
web.xmlFirst, create a folder called basic-web, and then let’s create the Gradle build file inside the folder: build.gradle
apply plugin: 'java'
apply plugin: 'war'
apply plugin: 'jetty'
apply plugin: 'eclipse-wtp'
repositories {
mavenCentral()
}
dependencies {
providedCompile 'javax.servlet:servlet-api:2.5'
runtime 'javax.servlet:jstl:1.1.2'
}The eclipse-wtp plugin allows us to import the project into Eclipse as a Dynamic Web Project to be run from Eclipse if desired. The war plugin extends the java plugin and adds support for packaging the WAR file. The jetty plugin adds tasks to support running our Gradle project in an embedded Jetty instance from our build-file. Notice that we are including the servlet-api as a “providedCompile” dependency. This means we do not want it to be packaged in the WAR, because it will be included in the application server in which it will run. Now, let’s create the web.xml descriptor file in src/main/webapp/WEB-INF: web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<display-name>HelloWorldServlet</display-name>
<servlet-name>HelloWorldServlet</servlet-name>
<servlet-class>com.codetutr.HelloWorldServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>We set up a simple servlet backed by com.codetutr.HelloWorldServlet and mapped to “/”. Finally, let’s create the servlet in src/main/java package com.codetutr: HelloWorldServlet.java
package com.codetutr;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorldServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.getOutputStream().write("Hello World.".getBytes());
}
}That’s all. We can now launch the jetty server and see our web application in action:
$ gradle jettyRunWar :compileJava UP-TO-DATE :processResources UP-TO-DATE :classes UP-TO-DATE :war :jettyRunWar
Now go to http://localhost:8080/basic-web to access your servlet. You should see “Hello, World.” on the screen. Full source: basic-web.zip Unpack the archive. Open command prompt at unarchived root. Type gradle jettyRunWar. Go to http://localhost:8080/basic-web.
Excellent one…really a good starting point for me