The page Directive in JSP

By: Sathya Narayana Viewed: 177 times  Printer Friendly Format    


The page directive specifies attributes for the page; all the attributes are optional, and the essential ones have default values, shown in bold:

<%@ page language="java"
          extends="package.class"
          import="package.class, package.*, ..."
          session="true|false"
          buffer="none|default|sizekb"
          autoFlush="true|false"
          isThreadSafe="true|false"
          info="Sample JSP to show tags"
          isErrorPage="true|false "
          errorPage="ErrorPage.jsp"
          contentType="TYPE|
                        TYPE; charset=CHARSET|
                        text/html; charset=ISO-8859-1"
          pageEncoding="default"
          isELIgnored="true|false"
%>

Bear the following in mind when using this directive:

  • The default buffer size is defined to be at least 8 kilobytes (KB).

  • The errorPage attribute contains the relative URL for the error page to which this page should go if there's an unhandled error on this page.

  • The specified error page file must declare isErrorPage="true" to have access to the Exception object.

  • The contentType attribute sets the MIME type and the character set for the response. The default value is "text/html" for standard JSP pages and "text/xml" when implementing JSP documents in Extensible Markup Language (XML) format.

  • The pageEncoding attribute defines the character encoding for the JSP page. The default is that specified in the contentType attribute or "ISO-8859-1" if none was specified there.

This is an example of the code that may be used for an error page:

<%@ page language="java"
          isErrorPage="true" %>

<html>
  <body>
    <!-- This displays the fully-qualified name of the exception
         and its message-->
    <%= exception.toString() %>
    <br>

    <!-- This displays the exception's descriptive message -->
    <%= exception.getMessage() %>
  </body>
</html>

The page will print the error message received.

This directive can also switch on support for scripting and EL in the JSP document, using the isELIgnored attribute, which sets Expression Language (EL) support. Settings in web.xml may influence the behavior of this attribute. For this attribute, a value of true enables support, and false disables it. The default value is true.



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