34</body> 35</html> in Java

Drawing QR Code in Java 34</body> 35</html>

In examining the page makeup in Listing 11-1, three areas stand out as possi bilities for common content: The definitions of the taglibs between lines 1 and 5 The inserted logo in lines 12-20 The footer section in lines 26-33 You can assume that other pages in the Web application are similar in structure they include the same taglib definitions, logo graphics, and

footer information Because these code snippets are common to so many other pages, you could simplify the code a lot by removing these repeated sections and putting them into their own separate files Then the original pages that contained the snippets could reference this content using the include directive and jsp:include tag You can extract the common features and put them into three separate files, as shown in Listings 11-2, 11-3, and 11-4

Listing 11-2

prefix= c uri= /WEB-INF/ctld %> prefix= fmt uri= /WEB-INF/fmttld %> prefix= html uri= /WEB-INF/struts-html-eltld %> prefix= tiles uri= /WEB-INF/struts-tilestld %>

Listing 11-3

<table width= 100% > <tr valign= top align= center > <td> <img src= images/webLogogif name= webLogo width= 425 height= 50 border= 0 > </td> </tr> </table>

Listing 11-4

<div align= center > <hr SIZE= 1 WIDTH= 100% ><br/> Comments or Questions <a href= mailto:support@othenoscom > Email Othenos Customer Support </a><br/> ©2003 Othenos Consulting Group<br/> </div>

You can use three elements to insert outside content into a JSP page: the include directive, the jsp:include tag, and the JSTL c:import tag The JSP include directive allows the insertion of static content into the JSP page at the time the page is converted into a Java class by the JSP engine This directive has the following syntax:

Highlights of the tag follow: The tag can place only static content in a JSP file, such as an HTML or JSP file The tag is processed only when JSP is converted into a Java class, not at request time If the included file is updated, JSP containers are not required to change the converted page to include new content Listing 11-2 shows the use of the include directive to insert the taglibsjsp segment into the loggedinjsp page You must include the taglibsjsp in the page before the page is converted to the Java class because the tags that the page uses (html, c, fmt, tiles) require that you define the library before the conversion can occur The library definition is in the taglibsjsp file Inserting taglibsjsp at request time would be too late Here is how you would insert it before the page is converted:

<!-- begin the taglib definitions --> <%@ include file= taglibsjsp %> <!-- end the taglib definitions -->

To include content at request time, you can use the jsp:include tag This tag can insert both static and dynamic content into the page when the page is requested The following is the syntax for jsp:include:

Highlights of the tag are as follows: The tag can include static (for example, HTML) or dynamic (for example, JSP) content Inclusions are processed at request time You can pass parameters to the included content The JSP container is aware when an included resource changes and gen erates new content based on the new file The flush attribute defaults to false If set to true, it indicates that the page, if buffered, should be flushed (written out) before including the new resource

The logojsp and footerjsp segments (Listings 11-3 and 11-4) are candi dates for including with the jsp:include tag Here is how they would look if you included them with jsp:include:

<!-- begin the logo for the application --> <jsp:include page= logojsp flush= true /> <!-- end of logo --> <!-- begin the footer for the application --> <jsp:include page= footerjsp flush= true /> <!-- end of footer -->

You may want to use the c:import tag from the JSTL library instead of jsp: include The c:import tag claims to reduce some of the buffering inefficien cies found in the jsp:include tag Another feature of the tag is its ability to retrieve resources from any URL The jsp:include tag is limited to resources in the same context as the current page The simplest syntax for the c:import tag is