This small post describes the process for upgrading xalan-java version to 2.7.1 to work compatible with Java 1.6.
Xalan-Java is an XSLT processor for transforming XML documents into HTML, text, or other XML document types.
The issues that needs to fix while upgrade XSL to work with Java JDK 1.6 and Xalan 2.7.1 will be discussed here and in this post we will look in to sample examples that help us to create XSL’s to work compatible with these new version.
Please note that the problems identified here work well with Java JDK 1.5. Therefore, these changes require only, if we want our XSL to parse successfully with Java JDK 1.6.
xsl:import
This element must appear as the first child node of xsl:stylesheet or xsl:transform. It should not appear in the end or middle of the stylesheet. Otherwise it throws exception
“Error! xsl:import is not allowed in this position in the stylesheet!”
xsl:template
xsl:template must either have name or match attribute. If the name attribute is omitted then there must be a match attribute. For example, the code
<xsl:template >
<xsl:text>
-- </xsl:text>
</xsl:template>
throw exceptions“Fatal Error! java.lang.RuntimeException: ElemTemplateElement error: xsl:template requires either a name or a match attribute.”
The below code will execute successfully.
<xsl:template name="main">
<xsl:text>
-- </xsl:text>
</xsl:template>
xsl:value-of
xsl:value-of cannot be enclosed under xsl:text.For example, the code
<xsl:text>
<xsl:value-of select="@name"/>
</xsl:text>
will throw exception
“Error! xsl:value-of is not allowed in this position in the stylesheet!”
The code
stream.Use StringBuffer/StringBuilder in XSL
XSL Code such as
<xsl:variable name="allTableNames" select="java:java.lang.StringBuffer.new()" />
<xsl:variable name="void0" select="java:append($allTableNames, concat('', $toAppend))" />
throw exception
java.lang.IllegalArgumentException: argument type mismatch
and java.lang.NullPointerException
The reason is that the
org.apache.xalan.extensions.MethodResolver picks a method whose argument types are not converted properly. This was noticed in the new versions of JVM due to the order at which they return all methods available for a given class and the issue is still not resolved yet.
Further information can be refer to
https://issues.apache.org/jira/browse/XALANJ-2374
https://issues.apache.org/jira/browse/XALANJ-2315
I have replaced
StringBuilder with Map to correctly transform the XSL.
XSL DTMNodeIterator
Consider the following XSL.
<xsl:variable name="temp_core_alias_value">
<xsl:choose>
<xsl:when test="'true'">
<xsl:text>, CASE WHEN </xsl:text><xsl:text>.
</xsl:text>
<xsl:text> IS NULL THEN </xsl:text>
</xsl:when>
<xsl:otherwise>
<xsl:text>,</xsl:text>
<xsl:text>.</xsl:text>
</xsl:otherwise>
</xsl:choose>
</xsl:variable>
<xsl:variable name="temp_core_alias" select="java:put($processedMap,
$temp_core_alias_value, 'Test Value')"/>
<xsl:variable name="hasValue"
select="java:containsKey($processedMap, $temp_core_alias_value)"/>
<xsl:if test="$hasValue = 'true'">
<xsl:text>Value exist in Map = </xsl:text>
<xsl:value-of select="java:get($processedMap, $temp_core_alias_value)"/>
</xsl:if>
</xsl:variable>
</xsl:variable>
At this point, we might expect java:containsKey($processedMap,$temp_core_alias_value) to return true and the output of the above as “Value exist in Map = Test Value” But when transform using Xalan-Java 2.7.1, the Map return false and therefore no output appear.
The reason is that the evaluating expression for the temp_core_alias_value variable would return
org.apache.xml.dtm.ref.DTMNodeIterator@e020c9 and therefore, the
contains method of the Map would always return false regardless of the key present.
We can transform
DTMNodeIterator to normal String form by concatenate an empty string with temp_core_alias_value variable like the following
<xsl:variable name="temp_core_alias_value" select="concat('', $temp_core_alias_value)" />
Adding this line right before put in to the Map would result in the normal expected output.
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