Components of JavaServer Pages JavaServer Pages are composed of standard HTML tags and JSP tags. JavaServer Pages support all HTML tags. For a listing of HTML tags, refer to your HTML manual.
The JSP components are categorized as follows:
- Directives
- Declarations
- Scriptlets
- Comments
- Expressions
Step 1 Create new Dynamic Web Project
Step 1.1 Create New Project
Go to File->New->Others… Select Dynamic Web Project under Web category then click Next. TypeServletDemo or whatever name you want in the Project name field.
Step 1.2 Configure Target Runtime
- Click New Runtime… button under Target Runtime.
- Select Apache Tomcat v7.0. Click Next.
- Click Browse button to specify Tomcat Server installation directory. The select the folder then click Ok.
- Click Installed JREs… button to add/remove or edit JRE definition. Remove existing one; then click Add button to configure new one. Select Standard VM; then click Next. Click Directory button to select the root folder ofJDK installation. Select the folder then click Ok. Click Finish.
- Check the JDK then click Ok.
- Change JRE to the JDK then click Finish.
- Click Finish the finish the project creation.
Step 2 Create New JSP File
- Right click to the project or WebContent folder, select New -> JSP File from the menu.
- You can choose any name, for example jspComponents.jsp.
- Click Finish.
- Eclipse IDE will generate some boilerplate code. We just clear all its content and replace with the followings code:
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<%@page import="java.util.Calendar"%> <h3>JSPs components</h3> <%--<%!String test = "Hello World";%> --%> <!-- get system time --> <%!private boolean isAM() { boolean am = false; if (Calendar.getInstance().get(Calendar.AM_PM) == Calendar.AM) { am = true; } return am; } String systemTime = Calendar.getInstance().getTime().toString(); %> <%if (isAM()) {%> Good morning. The time is: <%=systemTime%> <%} else {%> Good afternoon. The time is: <%=systemTime%> <%}%> |
The example above contains all JSPs components. Each of these categories is described in more detail in the next chapters.
Line 1: page directive
Lines 3, 4: comments
Lines 5-14: declarations
Lines 16, 18, 20: scriptlets
Lines 17, 19: between <%= %> are expressions
Step 3 Configure Tomcat
Select Servers window; in case it’s not there, go to Windows -> Show View-> Others… Select Server -> Servers; then click Ok.
If this is the first time you are creating a server, in the Servers area you will see a link as No servers are available click this link to create a new server. Click the link.
Define a New Server window will be opened, In Select the server type. Select Apache -> Tomcat v7.0 Server. Then click Finish.
Step 4 Deploy The Application
- Right click to the Tomcat Server select Add and Remove.
- Move the application (JSPDemo) from Available column to Configured. Then click on Finish to deploy it to tomcat server.
Step 5 Start Tomcat Server
Right click on the tomcat server and choose Start or simply click on the green start icon to start the server.
Step 6 Run The JSP
We assume that you install tomcat on default port (8080) and project name is JSPDemo. Open web browser and type:
http://localhost:8080/JspDemo/jspComponents.jsp
Output
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JSPs components Good afternoon. The time is: Tue Dec 01 15:00:37 ICT 2015 |
Note: for JSP, you don’t need to Clean & Build the project or restart the tomcat server before running. You just change the code, save the changes and run.
For java classes, you need to Clean & Build the project to re-compile the code. In case register new servlet, change settings in web.xml or server.xml… you need to Clean & Build the project and restart tomcat server.