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EJB 3.0 |
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The classes needed by the client are declared
using a JSP page directive (enclosed within the <%@ %> characters). Because locating the
business interface and creating the enterprise
bean are performed only once, this code appears
in a JSP declaration (enclosed within the <%!
%> characters) that contains the initialization
method, jspInit, of the JSP page. A scriptlet
(enclosed within the <% %> characters)
retrieves the parameters from the request and
converts it to a Float object. Finally, a JSP
scriptlet invokes the enterprise bean’s business
methods, and JSP expressions (enclosed within
the <%= %> characters) insert the results
into the stream of data returned to the client.
The full source code for the WebClient.jsp is
given below.
<%@ page contentType=”text/html;
charset=UTF-8" %>
<%@ page
import=”com.javajazzup.examples.ejb3.stateless.*,
javax.naming.*”%>
<%!
private CalculatorRemote calculator = null;
float result=0;
public void jspInit() {
try {
InitialContext ic = new
InitialContext();
calculator = (CalculatorRemote)
ic.lookup(“example/CalculatorBean/remote”);
System.out.println(“Loaded Calculator
Bean”);
} catch (Exception ex) {
System.out.println(“Error:”+
ex.getMessage());
}
}
public void jspDestroy() {
calculator = null;
}
%>
<%
try {
String s1 =
request.getParameter(“num1”);
String s2 = request.getParameter(“num2”);
String s3 =
request.getParameter(“group1”);
if ( s1 != null && s2 != null ) {
Float num1 = new Float(s1); |
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Float num2 = new Float(s2);
if(s3.equals(“add”))
result=calculator.add(num1.floatValue(),
num2.floatValue());
else if(s3.equals(“sub”))
result=calculator.subtract(num1.floatValue(),
num2.floatValue());
else if(s3.equals(“multi”))
result=calculator.multiply(num1.floatValue(),
num2.floatValue());
else
result=calculator.division(num1.floatValue(),
num2.floatValue());
%>
<p>
<b>The result is:</b> <%= result %>
<p>
<%
}
}// end of try
catch (Exception e) {
e.printStackTrace ();
}
%> |
The source code for the “index.jsp” is given
below that will actual call the client-design form.
<%@page language=”java” %>
<html>
<head>
<title>Ejb3 Stateless Tutorial</title>
</head>
<body bgcolor=”#FFFFCC”>
<p align=”center”><font size=”6"
color=”#800000"><b>Welcome to <br>
Ejb3-Jboss 4.2.0 Tutorial</b></font>
Click <a href=”ejb3/form.jsp”>Calculator
Example</a> to execute Calculator<br></p>
</body>
</html> |
3. Deploy calculator application on the
Application Server
To deploy the created example application we
are going to use Jboss 4.2.0 Application Server
about which you have read in the previous section of this Javajazzup issue. So you first
need to download the following tools to deploy
this application.
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Jan 2008 | Java Jazz Up | 19 |
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