hirondelle.web4j.ui.tag
Class HighlightCurrentPage

Object
  SimpleTagSupport
      hirondelle.web4j.ui.tag.TagHelper
          hirondelle.web4j.ui.tag.HighlightCurrentPage

All Implemented Interfaces:

JspTag, SimpleTag

public class HighlightCurrentPage
extends TagHelper

Suppress self-linking anchor tags (links), where a link has the current page as its destination.

Self-linking is usually considered to be poor style, since the user is simply led back to the current page.

Rendering links to the current page in a distinct manner has two benefits :

• the user is prevented from following a useless link
• the user can see 'where they are' in a menu of items

This tag provides two distinct techniques for identifying self-linking:

• the current URI ends with the link's href target. This is the default mechanism. The 'ends with' is used since the current URI (stored by the Controller in request scope) is absolute, while most HREF attributes contain relative links.
• the trimmed link text (the body of the anchor tag) matches the TTitle request parameter used by the WEB4J templating mechanism.

If these policies are inadequate, then isSelfLinkingByHref(String, String) and isSelfLinkingByTitle(String, String) may be overridden as desired.

Example use case.

<w:highlightCurrentPage styleClass="highlight">
  <a href='ShowHomePage.do'>Home</a>
  <a href='ShowSearch.do'>Search</a>
  <a href='ShowContact.do'>Contact</a>
</w:highlightCurrentPage>

If the current URI is

 http://www.blah.com/fish/main/home/ShowHomePage.do
 

then the output of this tag will be

  <span class="highlight">Home</span>
  <a href='ShowSearch.do'>Search</a>
  <a href='ShowContact.do'>Contact</a>

If the styleClass attribute is not used, then the output would simply be :

  Home
  <a href='ShowSearch.do'>Search</a>
  <a href='ShowContact.do'>Contact</a>

This final example uses the TTitle mechanism :

<w:highlightCurrentPage useTitle="true">
  <a href='ShowHomePage.do'>Home</a>
  <a href='ShowSearch.do'>Search</a>
  <a href='ShowContact.do'>Contact</a>
</w:highlightCurrentPage>

For a page with TTitle parameter as 'Home', the output of this tag would be as above:

  Home
  <a href='ShowSearch.do'>Search</a>
  <a href='ShowContact.do'>Contact</a>

Nuisance restriction : the href attribute must appear as the first attribute in the <A> tags.

Constructor Summary

HighlightCurrentPage()

Method Summary

protected String	getEmittedText(String aOriginalBody) Alter any links in the tag body which refer to the current page.
protected boolean	isSelfLinkingByHref(String aCurrentURI, String aHrefTarget) Determine if self-linking is present, using the current URI and the link's HREF target.
protected boolean	isSelfLinkingByTitle(String aLinkText, String aTTitle) Determine if self-linking is present, using the link text and the TTitle request parameter.
void	setStyleClass(String aCascadingStyleSheetClassName) Name of the Cascading Style Sheet class used for highlighting text related to the current page (optional).
void	setUseTitle(Boolean aUseTitle) Use the TTitle request parameter passed to this page.

Methods inherited from class hirondelle.web4j.ui.tag.TagHelper

checkForContent, crossCheckAttributes, doTag, getPageContext, getPageName, getRequest, getResponse

Methods inherited from class SimpleTagSupport

findAncestorWithClass, getJspBody, getJspContext, getParent, setJspBody, setJspContext, setParent

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HighlightCurrentPage

public HighlightCurrentPage()

Method Detail

setStyleClass

public final void setStyleClass(String aCascadingStyleSheetClassName)

Name of the Cascading Style Sheet class used for highlighting text related to the current page (optional).

For example, the link text could be highlighted in yellow in order to make it stand out more clearly from the other links. If this attribute is not specified, then the link text is simply presented as is, with no special styling.

Parameters:

aCascadingStyleSheetClassName - satisfies Util.textHasContent(String).

setUseTitle

public final void setUseTitle(Boolean aUseTitle)

Use the TTitle request parameter passed to this page.

Optional. Default is false. If set to true, then the default mechanism is overridden, and self-linking pages will be identified by comparing the link text to the page TTitle parameter. (The TTitle parameter is used in the WEB4J page templating mechanism).

getEmittedText

protected final String getEmittedText(String aOriginalBody)

Alter any links in the tag body which refer to the current page.

See examples in the class comment.

Specified by:

getEmittedText in class TagHelper

Parameters:

aOriginalBody - is the evaluated body of this tag. If there is no body, or if the body is present but empty, then it is null.

Returns:

the text to display in the resulting web page.

isSelfLinkingByHref

protected boolean isSelfLinkingByHref(String aCurrentURI,
                                      String aHrefTarget)

Determine if self-linking is present, using the current URI and the link's HREF target.

Overridable default implementation that simply checks if aCurrentURI ends with aHrefTarget. In addition, aCurrentURI is passed through EscapeChars.forHrefAmpersand(String) before the comparison is made. This ensures the text will match a valid HREF attribute.

isSelfLinkingByTitle

protected boolean isSelfLinkingByTitle(String aLinkText,
                                       String aTTitle)

Determine if self-linking is present, using the link text and the TTitle request parameter.

Overridable default implementation that checks if the trimmed aLinkText (the body of the <A> tag) and aTTitle are the same.