Developing Web applications with Tomcat and Eclipse
Apache Tomcat & Eclipse Platform make a great Web development platform
Required components
The Eclipse V3.2 Callisto integrated development environment (IDE) includes tools for doing Web development and integrating with servers. So, aside from the software development kit (SDK), you need only Eclipse and Apache Tomcat installed. The versions featured in this article are listed below.
Table 1. Components and versions used
| Component | Version used in this article |
|---|---|
| Eclipse Platform | 3.2.2 |
| Java™ EE 5 SDK | 1.5.0_09 |
| Apache Tomcat | 5.5.20 |
The Eclipse IDE is an open source IDE used as the development environment for your JavaServer Pages (JSPs) and Java files. With the Web and Java 2 Platform, Enterprise Edition (J2EE) Development tools installed, Eclipse is great tool for creating HTML, JSPs, and servlets.
You need the Java SDK to run servlets on your machine. Finally, Apache Tomcat is an open source Web and servlet container, used in the official reference implementations for Java Servlet and Java Server Pages.
Installation
Installation of Eclipse and Tomcat is similar — both are extracted from the archive file format into a folder on your hard disk. If you ever want to uninstall either, it's as simple as deleting the directory in which you extracted the files.
Install Eclipse
To install the Eclipse IDE, unpack the compressed (.zip or .tar.gz) file you downloaded from Eclipse, then move the unpacked folder into a convenient location. I try to install it in a location that follows the conventions of whatever operating system I'm using. If I'm installing Eclipse on a Macintosh, I put the Eclipse folder in the Applications folder. If I'm using Microsoft® Windows®, I put the unpacked folder into the C:\Program Files directory.
Once you've downloaded and installed Eclipse, start it up. Before you can create a Web project, you need to install the J2EE and Web Development plug-ins. Fortunately, it's easy to install the plug-in using the Callisto Discovery Site.
Install the Web tools
With the Eclipse IDE running, select Help > Software Updates > Find and Install. This option lets you download and install the Web tools without going to a Web site.
Select Search for New Features to Install, as shown below, then click Next.
Figure 1. Install/Update window
Select Callisto Discovery Site, as shown below, then click Next.
Figure 2. Select the Callisto Discovery Site
Under Callisto Discovery Site, check the Web and J2EE Development box. The wizard immediately warns you that you're missing dependencies. Click Select Required, and these warnings should disappear. Some or all of the components in the Graphical Editors and Frameworks and Models and Model Development categories are selected (as shown in Figure 3) because they're required for the installation of the Web and J2EE plug-ins.
Figure 3. Select features for installation
Click Next to continue, and license agreements appear for each feature you've selected. If you agree with the licenses, accept them and follow the wizard through the rest of the process. When the IDE is finished installing the plug-ins, it asks you to restart Eclipse in order for the changes to take effect. Be sure you restart the IDE before continuing.
After you restart the IDE, the new features are available to begin developing dynamic Web projects.
Install Tomcat
To install Apache Tomcat, extract the files from the downloaded archive and place them into a directory. I put them in my C:\apps directory to make them easy to locate later. That's it for now; use Eclipse as shown later to start Tomcat.
Create a new Web project
From the Eclipse IDE, select File > New > Project to
view the project wizards. Type Web in the Wizards box, and
the New Project window filters the wizards to show the ones that match.
This is an easy way to locate the wizard you want instead of going through
each item.
Choose Dynamic Web Project from the list. You use the Standard Web Project Wizard to make static HTML Web projects. You can technically use Tomcat to run static Web sites, although a Web server such as Apache Web Server may be a better choice for static content. Web servers built specifically for serving up static pages tend to have less overhead and are tuned for that purpose.
Target a runtime
Under Target Runtime, you see <None>, as shown in Figure 4, because you haven't created a runtime yet for Apache Tomcat. Click New to open the New Target Runtime Wizard. Select Apache Tomcat V5.5 from the Apache folder, as shown in Figure 5, then click Next.
Figure 4. Create a new dynamic Web project
Figure 5. Create a new server runtime
Now you have the opportunity to name your runtime, although the default name Apache Tomcat V5.5 is fine. Click Browse to locate the base folder for your Apache Tomcat configuration (mine is C:\apps\apache-tomcat-5.5.20, as shown in Figure 6). I recommend leaving the IBM® Java Runtime Environment (JRE) version the same as the workbench default JRE, unless you have a specific reason to change it. Once you've entered a valid directory, click Finish to create the runtime configuration.
Figure 6. Define the server location
You're asked if you want to switch to the J2EE Perspective. I always answer yes because that perspective includes views like the Servers view, which help to start and stop Tomcat later. You can always open the Servers view by selecting Window > Show View.
Add the server
In the Servers view is a view that contains nothing. This view is for application and Web servers; it lets you control them and monitor their status. To control Tomcat directly from the comfort of the IDE, add a reference to Tomcat by selecting New > Server from the context-sensitive menu. The New Server wizard, as shown in Figure 7, will default to the Apache Tomcat V5.5 runtime you just created.
Figure 7. Define a new server
Click Next. You're asked whether you want to add projects to the server. Select the project you created in the previous steps, then click Add.
Figure 8. Add the projects to the server
Click Finish to close the wizard. Now the Servers view contains the Tomcat V5.5 Server with the project under it.
Figure 9. The Tomcat server in the Servers view
Create a sample page
The easiest way to test your new dynamic Web project and Tomcat server integration is to create a simple JSP and deploy it to Tomcat. You can create the new JSP file by selecting File > New > Other, or you can use the context-sensitive menu by right-clicking the project name in the Project Explorer view and selecting New > JSP.
Make sure the parent folder is WebContent and name the file index.jsp. Click Finish to create the page using the default template. If you click Next, you can choose different templates to use (such as HTML or XHTML) for the new page. The defaults are fine for this test.
The page code shown below displays a simple date so you can see it working.
Listing 1. Contents of index.jsp
<%@ 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>My Title</title>
</head>
<body>
<% java.util.Date d = new java.util.Date(); %>
<h1>
Today's date is <%= d.toString() %> and this jsp page worked!
</h1>
</body>
</html>Deploy the page
Now that the test page is complete, use Eclipse to redeploy it to Apache Tomcat. In the Servers view, notice that State is set to Republish. That is because changes have been made since the project was last deployed to the server. Right-click the server and select Publish from the menu. The state changes to Synchronized once the project has been deployed to the server.
With the project successfully deployed and the server started, open a browser and navigate to http://localhost:8080/[ProjectName]/ (where [ProjectName] is the name of the dynamic Web project you created). The new Web page you created appears, and the date should be current. If you refresh the page, the date changes.
Figure 10. Output of index.jsp in a browser
Hello World servlet
You can add Java servlets to your project and deploy them. To create a quick servlet you can use for testing purposes, use the Servlet Wizard by right-clicking your dynamic Web project in the Project Explorer view and selecting New > Other. Under the Web folder, select Servlet, then click Next.
Add the package name com.example.servlets next to Java
Package and add HelloServlet next to
Class name. Click Finish. This is an
example, so the defaults are fine. The Eclipse IDE generates a servlet
class for you. To watch the test servlet in action, add a line in the
doGet() method to print a message to the ResponseWriter. The
servlet class should look like the one shown below.
Listing 2. Contents of HelloServlet.java
package com.example.servlets;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class for Servlet: HelloServlet
*
*/
public class HelloServlet extends javax.servlet.http.HttpServlet
implements javax.servlet.Servlet {
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public HelloServlet() {
super();
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request,
HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.getWriter().write("Hello, world!");
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request,
HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
}
}After you add the servlet, the Eclipse IDE notes that your project has
changed. Look again at the Servers view; Restart now appears in the Status
column next to the Tomcat server. To restart the server, right-click the
server in the Servers view, then select Restart >
Start. Open a browser and navigate to
http://localhost:8080/[ProjectName]/HelloServlet (where [ProjectName] is
the name of your dynamic Web project). The text "Hello, world!" appears in
the browser window. You can add the date, similar to the code in the
index.jsp file, to the doGet() method, and redeploy the
servlet using the Eclipse IDE.
Summary
It's productive to develop JSPs and servlets without having to leave the IDE to start, stop, or deploy to your server. The combination of Eclipse and Apache Tomcat provides an easy integrated environment that enables you to speed up development.