Friday, 1 March 2013

JSP (Web Applicattion)

Konsep dari Exception Handling serta pemodelan dari Try, Throw, Catch dan Finally dijelaskan.

An exception is an event that occurs during the execution of a program and it disrupts the normal working of the instructions in the program. An exception can occur if you trying to connect to a database which doesn't exists or the database server is down, it may be thrown if you are requesting for a file which is unavailable, then the exception will be thrown to you.

We can handle the exceptions in jsp by specifying errorPage in the page directive, <%@ page errorPage = "errorPage.jsp">. If any exception will be thrown then the control to handle the exception will be passed to that error page where we can display a information to the user about what's the reason behind throwing the exception.

In this example we are going to handle the run- time exception. To make a program on this we are using three pages.

A Html Form: It is used to display a form to the user where he will enter the first and second number.

Controller class: This class is a jsp page which recieves the values entered by the user and prints it on the user screen. If any exceptions exception occurs then it will forward it other page which will handle the exception.

Exceptional Handler: This jsp page is actually an error page to which the control will be passed by the controller when the exception is thrown.


Code of the program is given below: (Baca form.txt) dan Bab 5 - Java Beans



 <html>
<head>
    <style>
    body, input { font-family:Tahoma; font-size:8pt; }
    </style>
</head>
<body>
<table align="center" border=1>

<form action="formHandler.jsp" method="post">
    <tr><td>Enter your first Number: </td>
    <td><input type="text" name="fno" /></td></tr>
    <tr><td>Enter your Second Number: </td>
    <td><input type="text" name="sno" /></td></tr>
    <tr ><td colspan="2"><input ty
     pe="submit" value="Submit" /></td></tr>
</form>
</table>
</body>
</html>
SCRIPT SELANJUTNYA

<%@ page errorPage="exceptionHandler.jsp" %>
<html>
<head>
    <style>
    body, p { font-family:Tahoma; font-size:10pt; }
    </style>
</head>
<body>

<%
    int fno;
    int sno;

        fno = Integer.parseInt(request.getParameter("fno"));

        sno = Integer.parseInt(request.getParameter("sno"));
       

        int div=fno/sno;

%>

<p>Division is : <%= div %></p>

<p><a href="form.html">Back</a>.</p>

</body>
</html>
AND NEXT SCRIPT



 <%@ page isErrorPage="true" import="java.io.*" %>
<html>
<head>
    <title>Exceptional Even Occurred!</title>
    <style>
    body, p { font-family:Tahoma; font-size:10pt;
        padding-left:30; }
    pre { font-size:8pt; }
    </style>
</head>
<body>

<%-- Exception Handler --%>
<font color="red">
<%= exception.toString() %><br>
</font>

<%
out.println("<!--");
StringWriter sw = new StringWriter();
PrintWriter pw = new PrintWriter(sw);
exception.printStackTrace(pw);
out.print(sw);
sw.close();
pw.close();
out.println("-->");
%>

</body>
</html>

























































































Posted By: brema bastanta

JSP (Web Applicattion)

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