ECLIPSE WEB TOOLS PLATFORM developing java web applications PHẦN 2 doc

Iteration 1: J2EE Web Applications 49

3. Click the Next button to display the Tomcat Server page. Click the Browse

button to select the directory where you installed Tomcat (see the Getting

Tomcat sidebar), for example,

E:\jakarta-tomcat-5.0.28

The Tomcat installation directory field should now show the selected

directory (see Figure 3.4).

Figure 3.4 Tomcat Server

4. The JRE field is initialized to the Workbench default JRE, which is the JVM

you used to launch Eclipse.

JDK Required for JSP Development

Part of the server runtime environment setup process involves specifying the JRE to

use for launching Tomcat. Be sure to specify a full JDK instead of just a JRE because

you’ll be doing JSP development. If you do not currently have a JDK defined to Eclipse,

add the one you previously installed (see the Getting a JDK sidebar). JSP development

requires a Java compiler, which is included in the JDK but not the JRE. JSP compilation

will fail if you specify a JRE. Note that you can precompile your JSPs in order to use a

JRE in your production server environment.

Click the Installed JREs button to open the Installed JREs wizard. This wizard

lets you define additional JREs to Eclipse. Click the Add button and select

the directory where you installed the JDK (see the Getting a JDK sidebar),

for example,

E:\ibm-java2-142

The JDK is added to the Installed JREs page. Select its checkbox to make it

the default JRE (see Figure 3.5), and click the OK button to return to the

Tomcat Server page.

50 CHAPTER 3 • Quick Tour

Figure 3.5 Installed JREs

5. Select the JDK from the drop-down list of the JRE field (see Figure 3.4).

When WTP launches Tomcat later, it will use the specified JDK. Click the

Finish button to complete the definition.

Tomcat is now listed on the Installed Server Runtime Environments page (see

Figure 3.6). You have now extended Eclipse with a J2EE servlet container

and are ready to create your first Java Web application development

project.

Create a Dynamic Web Project

We assume you are familiar with the Eclipse concepts of workspace, project, and

builder. Recall that an Eclipse workspace contains a set of projects. You typically

put projects that are related to each other in the same workspace. For example, in

J2EE development, you would put related Web, EJB, and utility projects in the

same workspace. Each project has a set of builders associated with it. Builders are

what give the project its intelligence. Builders know how to process the artifacts in

a project. The most common example of a builder is the Eclipse incremental Java

compiler, which knows how to compile your Java source files into class files.

WTP provides builders for Java Web applications. These builders know, for

example, how to package the artifacts in J2EE modules so that they can be

deployed to J2EE application servers.

In general, a J2EE application will contain several modules. For example, you

might want to use a Web module for the presentation logic and an EJB module

for the business logic. Here you’ll just develop a Web module. Do the following to

add a Web module to your workspace:

Iteration 1: J2EE Web Applications 51

Figure 3.6 Installed Server Runtime Environments with Tomcat Added

1. To begin development, create a new dynamic Web project by invoking the

File
New
Project menu command to open the New Project wizard.

Select Web
Dynamic Web Project as the project type (see Figure 3.7).

52 CHAPTER 3 • Quick Tour

Figure 3.7 New Project

2. Click the Next button. The Dynamic Web Project page is displayed (see

Figure 3.8). Enter Web1 in the Project Name field. Note that Apache Tomcat

is selected as the Target Runtime since it is the only server runtime environ￾ment you have defined. The Configurations field lets you select a predefined

configuration of project facets. Leave the setting as <custom> for now. You

can also ignore the checkbox to add the Web module to an EAR project

since Tomcat is just a servlet container and doesn’t support EARs.

3. Click the Next button to advance to the Project Facets page (see Figure 3.9). A

facet is part of the runtime configuration of a project, such as the version of

Java or J2EE. Facets will be discussed in more detail in Chapter 6. For now,

simply accept the selections.

4. Click the Next button to advance to the Web Module page (see Figure 3.10).

You can change some of the project settings here. For example, the Context

Root of the Web application defaults to its project name, Web1. Accept the

defaults for now.

Iteration 1: J2EE Web Applications 53

Figure 3.8 Dynamic Web Project

Figure 3.9 Project Facets

54 CHAPTER 3 • Quick Tour

5. Click the Finish button to create the Web project. Since this is the first

time you have created a Web project, you are prompted to accept the

J2EE license from Sun (see Figure 3.11). WTP will next attempt to down￾load the J2EE schemas from the Sun Web site, so you must accept the

license before WTP proceeds. Products built on top of WTP may have

obtained the right to redistribute the J2EE schemas, in which case you

won’t see this dialog.

6. Click the I Agree button to accept the license. Note that if you

do not accept the license, then WTP will be unable to validate the

J2EE XML artifacts, such as the deployment descriptors (e.g., web.xml),

you create.

WTP has a special J2EE perspective and will attempt to switch to

it when you create any J2EE project, such as a dynamic Web project

or an EJB project. One of the user interface design guidelines of Eclipse is

to not switch perspectives without asking the user if they want to.

You are therefore prompted to switch perspectives (see Figure 3.12).

Figure 3.10 Web Module

7. Click the Yes button to agree to the switch. The wizard opens the J2EE

perspective for you so you can see the logical structure of your modules.

The J2EE Project Explorer view (see Figure 3.13) now shows the project

structure after Web1 has been created. Note that the wizard created some

folders and files under the Web1 module. These items are defined by the

J2EE specification. For example, the WebContent folder is the root of the

Web application and is where the normal Web content, such as HTML

Iteration 1: J2EE Web Applications 55

Figure 3.12 Open Associated Perspective

Figure 3.11 License Agreement