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my tailor uses Custom tag

Custom tags to avoid placing java code inside the JSP page "scripting", so that the JSP page is able to concentrate only on the presentation logic.

  • old "classic" where a developer has to adjust the flow, from start go to ?? , will evaluate the body or not, all done depending on the return value of overridden methods .
    • instance of tag handler is reused, can't rely on constructor to do initialization, better to use setPageContext( ).
  • now everything is done overriding just one method.
    • simple tag model never reuse tag handler instances.

body content:
  • in practice content is not processed at all
    • JspWriter out=getJspContext().getOut();
    • out.print(" ... ");
    • getJSPBody.invoke(null);
    • out.print(" ... ");
  • Modify to process body content
    • StringWriter writer=new StringWriter();
    • getJSPBody.invoke( writer );
    • String bodyContent=writer.toString();
.tld addresses to custom tag, so how to know about
  1. explicit "within web.xml"
  2. implicit "must contain the optional uri element"
    1. place the .tld in /WEB-INF or within one of its sub directory 
    2. use a packaged file, which is placed in /WEB-INF/lib
with Java-based tags tag handler is a java class, where as with Jsp based tags the tag handler is a Jsp page.

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