Java+XSL, calling Java code from within template
https://stackoverflow.com/questions/4486773
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I'm working with XSL templates in Java, and I'm trying to build a custom tag that will call some Java code, then put a result inside the template. I'm using XOM as my XML engine. I'm kind of new with both XOM and XSL, so I'm not even sure if this is a smart idea.
A very simple example of something I want to do is this, where my_ns is a custom namespace with 'custom_tag' that the method custom tag
<xsl:template name="foo">
<my_ns:custom_tag />
</xsl:template>
public Node custom_tag() {
return Node("<a/>");
}
#result of calling the template foo
<a/>
I'm open to suggestions for involve alternate ways of calling Java from a XSL template.
Solution
This is more a question about if your XSLT processor can execute/call java code from within the template more than your XML engine/parser/api. The default XSLT processor for java is Xalan-C or Xalan-J (can't remember which) from the Apache Software Foundation. I do believe both of them allow for extension functions to execute java code inside the method. I've done JDBC sql queries inside a XSL stylesheet before using a xalan-j extension function. I also recall reading that the Saxon XSLT processor also allows this functionality. You'll have search your XSLT processor to get the specifics on to implement this.
The question on whether this is a good idea or not really depends on the problem. Even though I used the SQL extension function mentioned above and it fit the bill in that case, I felt really dirty about it afterwards. The reason I say this is because you lose portability between XSLT processors when you add in the vendor-specific extension functions.
Your example shows you are just simply creating a new node in the output and if that is the case, I don't see the need to have java do this when that is one of the main functions of XSLT: creating nodes. I suspect your real problem is more complex than simply creating a node so I'll suggest you may want to look into doing all the work in java to get the results you are looking for OR doing some of the work in java and passing a parameter (name/value pair using the xsl:param element) to your XSL stylesheet a runtime.
Here's some quick sites to get you started:
