CODEWITHSUNDEEP
javajsp
billc.cn
billc.cn

Reputation: 7317

XSLT <xsl:element> equivalent in JSP?

When writing XML-compliant JSP, it is difficult to generate different HTML tags according to the input (e.g. when outputting the different tags in a <table>).

The standard solution is to use if or choose tags, but sharing code inside the HTML tag becomes a problem. E.g.

<c:choose>
 <c:when test="${i.tag = 'th'}><th> <!-- 100 lines of code --> </th></c:when>
 <c:when test="${i.tag = 'td'}><td> <!-- 100 lines of code duplicated?! --> </td></c:when>
</c:choose>

XSLT offers an <xsl:element> tag which allows you to build a tag and its attributes with standard XML syntax. Is there such a tag in any tag library in JSP?

Upvotes: 1

Views: 251

Answers (3)

Ravi K Thapliyal
Ravi K Thapliyal

Reputation: 51711

Shouldn't you be doing this like?

<c:choose>
 <c:when test="${i.tag = 'th'}"><th></c:when>
 <c:when test="${i.tag = 'td'}"><td></c:when>
</c:choose>
 <!-- 100 lines of code --> 
<c:choose>
 <c:when test="${i.tag = 'th'}"></th></c:when>
 <c:when test="${i.tag = 'td'}"></td></c:when>
</c:choose>

If you want your markup to be valid XML; make use of a custom tag that wraps all the Java code you want to avoid duplicating. Your markup would then look something like

<c:choose>
 <c:when test="${i.tag = 'th'}">
  <th>
   <my:customTag anyAttributes="th-related-values-if-any" ... />
  </th>
 </c:when>
 <c:when test="${i.tag = 'td'}">
  <td>
   <my:customTag anyAttributes="td-related-values-if-any" ... />
  </td>
 </c:when>
</c:choose>

Alternatively, the following hack (suggested by @Uooo) can be used to pass XML validators.

<c:choose>
 <c:when test="${i.tag = 'th'}"><c:out value="&lt;th&gt%" /></c:when>
 <c:when test="${i.tag = 'td'}"><c:out value="&lt;td&gt%" /></c:when>
</c:choose>
 <!-- 100 lines of code --> 
<c:choose>
 <c:when test="${i.tag = 'th'}"><c:out value="&lt;/th&gt%" /></c:when>
 <c:when test="${i.tag = 'td'}"><c:out value="&lt;/td&gt%" /></c:when>
</c:choose>

Upvotes: 1

Uooo
Uooo

Reputation: 6344

You could create a seperate JSP containing your "100 lines of code" and include it.

Replace your <!-- 100 lines of code --> with:

<jsp:include page="hundredLines.jsp">
    <jsp:param name="beanParam" value="beanValue"/>
</jsp:include>

And in your hundredLines.jsp:

Bean can be used like ${beanParam}

Upvotes: 1

Bob Dalgleish
Bob Dalgleish

Reputation: 8227

No. JSP requires knowing the tags when it builds its trees. That makes the operation of JSP more robust

However, you can address the duplicated code by factoring it into a separate JSP file and including it, depending on the implementation of JSP you are using.

Alternatively, you can create a JSP tag that holds the 100 lines of code. It is probably not worth while to do this.

Finally, you could, instead of using th and td, use styles on td to make td look like th. That would make the element look like

<td style="${i.tag == 'th' ? '' : 'font-style: bold; text-align: center;'}">
  100 lines of code
</td>

I know I don't have the style quite right, but you could use styleClass instead and play with it in your CSS.

Upvotes: 0

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