Setting up Gradle web project in Eclipse (on Tomcat Server)

In this post I’ll focus on the most annoying part of the software project — configuration. I’m going to show you how I had set up basic environment to code, build, deploy and run my Spring MVC project — Library Portal. I ‘ll go thru each step of the whole process, from brand new web project to first ‘Hello World!’ that will show up on the test page. Let’s get hands dirty!

Step 1. Installing Java SE Development Kit (JDK) and Eclipse IDE #

First things first, I needed to to have both of these to run any Java application (including Spring project). JDK is a neccessary toolkit for any Java project and Eclipse IDE is a really practical tool to make coding more comfortable and more efficient.

I don’t want go into details with installation of both these things, as they are pretty straightforward. Here are the links, where can be found their latest releases to download:

Java SE Development Kit - Java SE - Downloads | Oracle Technology Network | Oracle *Java SE downloads including: Java Development Kit (JDK), Server Java Runtime Environment (Server JRE), and Java Runtime…*www.oracle.com

Eclipse IDE - Eclipse desktop & web IDEs *Eclipse is probably best known as a Java IDE, but it is more: it is an IDE framework, a tools framework, an open source…*www.eclipse.org

In this project I’ve been interested in Java EE edition of the Eclipse. When I was writing this post the latest release version was Oxygen and could be downloaded from here: Eclipse IDE for Java EE Developers | Packages *Tools for Java developers creating Java EE and Web applications, including a Java IDE, tools for Java EE, JPA, JSF…*www.eclipse.org

Step 2. Installing Gradle plugin into Eclipse #

In short, Gradle is very useful tool for automating build task of the application and standarization project structure. The main reason that I am using it is for this cool feauture called dependency management. Thanks to ti I don’t need to wonder how to download external libraries to my project. It skips the exhausitng process of finding it on the internet, downloading and then adding it to the project. Instead you need to type single — YES, SINGLE!- line into a build.gradle file and refresh project. That’s it!

Gradle also support other features like creating own task that can be included during build script of the project, e.g. before running application Gradle can copy some resources into your project, or maybe create database and populate with some basic input that can be used for testing. There are many options to go (for more information, please see the Reference section at the end of my post).

Installing it in Eclipse is also rather straightforward. Here is a video of how to do it:

Step 3. Building Gradle web project in Eclipse #

Once I had all tools set up I’ve moved to the part which was creating basic Gradle project and converting it into Java Web application.

First, I’ve created new standard Gradle project with all defaults parameters in Eclipse. Next I’ve added Dynamic Web Module facet into this project. To do that I’ve right clicked on the project name in the Project Explorer window and then chose Properties. A new window showed up. On the left there was option tree, from which I’ve picked Project Facets. From the list on the right side of the window I’ve selected Dynamic Web Module,then Apply and OK button (below is the screenshot of Project Properties window).

Ok, so now a tricky part. One of the outcomes of previous step was that Eclipse created new folder and subfolders where should be stored all frontend files of the application (HTML, JSP, CSS, etc.) — WebContent. To make it work with Gradle I would needed to make some configuration in a build.gradle file, but because I am lazy and most of web tutorials have different folder structure I’ve went with standard Gradle config. So in my case I’ve deleted hole *WebContent folder and *create webapp folder and its subfolder WEB-INF under *src/main. *Also a resource folder was created— it will be used for some other features which I will talk further in my next stories. After thatmy file structure looked like this:

library-spring/
    src/
        main/
            java/
            resources/
            webapp/
                    WEB-INF/
        test/
            java/

Last task was to tell Gradle that my project is a web application. Thus to convert java project into it I’ve modified build.gradle by adding apply plugin: ‘war’ line into it. I’ve also cleared all comments that were automatically generated by the Eclipse so the I had following code:

apply plugin: 'java-library'
apply plugin: 'war'

repositories {
          jcenter()
}

dependencies {
         api 'org.apache.commons:commons-math3:3.6.1'
         implementation 'com.google.guava:guava:21.0'
         testImplementation 'junit:junit:4.12'
}

To apply this change I’ve right clicked on the build.gradle file in Project Explorer, found Gradle on the list and clicked Refresh Gradle Project.

Step 4. Installing Gradle Tomcat plugin #

So far my project has been created as a web application, but if I want to deploy it on a server each time I would need to convert it to war file and then manually run it on server, which is highly inconvieniet. That’s why I have ended up with installing a Tomcat plugin to Eclipse so, when I build a project via Gradle task it will be automatically deployed on a Tomcat server.

I’ve added following lines to build.gradle file and refreshed it:

apply plugin: 'com.bmuschko.tomcat'
apply plugin: 'eclipse-wtp'


buildscript {
       repositories {
             jcenter()
       }
       dependencies {
             classpath 'com.bmuschko:gradle-tomcat-plugin:2.4.1'
       }
}


dependencies {
         def tomcatVersion = '8.0.46'
         tomcat "org.apache.tomcat.embed:tomcat-embed-core:${tomcatVersion}",
         "org.apache.tomcat.embed:tomcat-embed-logging-juli:${tomcatVersion}",
         "org.apache.tomcat.embed:tomcat-embed-jasper:${tomcatVersion}"
         api 'org.apache.commons:commons-math3:3.6.1'
}


tomcat {
         httpPort = 8080
         enableSSL = true
         contextPath = '/library-spring'
}

Now everything was set up, so in order to deploy the application I need to run it via Gradle task — tomcatRun. To make it easier in future, so I would only need to click the Run button in Eclipse to deploy the app I’ve created new run task.

I’ve found Run/Run Configurations… and after entering it, in the new window picked Gradle Project folder and clicked New icon. In the form I have entered following input:

• Name: Library Spring — Run

• Gradle Task: tomcatRun

• Working Directory: ${workspace_loc:/library-spring}

To finalize I’ve clicked Apply button and Run it to test it.

Step 5. Testing simple Java EE application #

Finally, let’s find out if all that effort was worth it. To test it I’ve created a simple web project, without any Spring framework code. To achieve it I’ve added two things — JSP and web.xml file. The purpose of the first one is pretty straightforward, it is the page that will be displayed in a browser after deploying the app on a server. The latter is more complex. It is so called Web Application Deployment Descriptor (what a scary name!), and it provides some initial parameters (like servlets, welcome files, filters and other components) that a server needs to know.

In my case I’ve created a really simple JSP page (index.jsp, it is located in a folder src/main/webapp) that has only ‘Home page’ in its body.

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
  <head>
  <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
  <title>Home page</title>
  </head>
  <body>
    Home page
  </body>
</html>

Next I’ve created the web.xml file (located in src/main/webapp/WEB-INF folder) that included only one tag: <welcome-file-list>. It contains all the files that server will be looking for to display, if no particular file/path will be specified. Important note, the file name on the list must be the same as I have provided above, otherwise file will be skipped and you get HTTP 404 error message.

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

<web-app version="3.0" 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_3_0.xsd">

	<welcome-file-list>
		<welcome-file>index.jsp</welcome-file>
		<welcome-file>index.html</welcome-file>
	</welcome-file-list>

</web-app>

At last, the configuration was over! Once I had run the Gradle deploy task and typed localhost:8080/library-spring on my browser I have ended up with sweet text printed — ‘Home page’!

And that’s it! It doesn’t looks so scary now, but believe me, I was looking for this outcome for quite some time. Here is the link to my GitHub repository, where you can find the whole project that I have created for this entry post:

wkrzywiec/Library-Spring | GitHub.com

References #

I wouldn’t never manage to achieve this without first searching thru the internet looking for some answers, so here is a list of some resources that I have found really useful:

• Eclipse IDE - Tutorial | vogella.com
• Gradle Build Tool | gradle.org
• Building Java Web Applications | guides.gradle.org
• Create a Gradle Java Web Application and run on Gradle Tomcat Plugin | Plugino7planning.org