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Java Enterprise Best Practices
book

Java Enterprise Best Practices

by O'Reilly Java Authors
December 2002
Intermediate to advanced content levelIntermediate to advanced
288 pages
9h 46m
English
O'Reilly Media, Inc.
Content preview from Java Enterprise Best Practices

Consider Using Filters to Simplify URLs

One drawback with the simple templating solution implemented by a layout page is that all links to the JSP pages must include the layout page name plus a query string—e.g., layout.jsp?page=page1. Example 9-6 shows parts of the navigation menu page with this type of link.

Example 9-6. Navigation page with links to layout page
<%@ taglib prefix="c" uri="http://java.sun.com/jstl/core" %>
   
<table bgcolor="lightblue">
  <tr>
    <td>
      <c:choose>
        <c:when test="${param.page =  = 'page1'}">
          <b>Page 1</b>
        </c:when>
        <c:otherwise>
          <a href="<c:url value="layout.jsp?page=page1" />">Page 1</a>
        </c:otherwise>
      </c:choose>
    </td>
  </tr>
   . . . 
</table>

If you want to be able to use more traditional URLs instead, you can use a filter. The filter component type was introduced in the Servlet 2.3 specification. A filter is invoked before a request is delivered to the target servlet or JSP page and is a powerful tool for applying request and response processing to a group of web application resources. The filter shown in Example 9-7 converts URLs of the form pageName.jsp to URLs of the form layout.jsp?page=pageName, which are behind the scenes at runtime.

Example 9-7. Filter that allows the layout page to be invoked with regular URLs
package com.ora.j2eebp.jsp; import java.io.*; import java.net.*; import javax.servlet.*; import javax.servlet.http.*; public class URLConversionFilter implements Filter { private static final String LAYOUT_PAGE = "/layout.jsp"; private static final ...
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Publisher Resources

ISBN: 0596003846Supplemental ContentErrata Page