The JSP Files (part 7): Bugs, Beans And Banks - Bad News (
Page 4 of 7 )
The exception-handling routine "error.jsp"
can be as simple or complex as you want to make it. If you want something
friendly and easy to understand, you could use the following:
<html>
<head>
<basefont face="Arial">
</head>
<body bgcolor="white">
<h2>Oops!</h2>
Something bad just happened. Click here to go back to the main page.
</body>
</html>
Now, if you run the example above again, JSP should
automatically divert you to this page instead of grossing you out with long and
icky error messages.
The script above simply notifies the user that an
error has occurred; it says nothing about the type of error, or the reasons for
its occurrence. If you'd like to display this as well, you need to use the
built-in Exception object to obtain information about the exception. The next
example uses a modified "error.jsp" to illustrate this:
<%@ page isErrorPage="true" %>
<html>
<head>
<basefont face="Arial">
</head>
<body bgcolor="white">
<h2>Oops!</h2>
Something bad just happened:
<br>
<b><i><%= exception.getMessage() %></i></b>
</body>
</html>
And this time, the output will be a little more
helpful.
Oops!
Something bad just happened:
/ by zero
Pay special attention to the first line of the script;
the directive
<%@ page isErrorPage="true" %>
tells JSP that this is an error page, and initializes an
instance of the Exception object for use.
The Exception object comes with
a couple of useful methods - the exception.getMessage() method is used to obtain
a description of the error, while the exception.printStackTrace() method is used
to print debugging information.
