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org.apache.struts2.views.xslt
Class XSLTResult

java.lang.Object
  extended by org.apache.struts2.views.xslt.XSLTResult
All Implemented Interfaces:
Result, Serializable
public class XSLTResult
extends Object
implements Result

XSLTResult uses XSLT to transform an action object to XML. The recent version has been specifically modified to deal with Xalan flaws. When using Xalan you may notice that even though you have a very minimal stylesheet like this one 

 <xsl:template match="/result">
   <result/>
 </xsl:template>

Xalan would still iterate through every property of your action and all its descendants.

If you had double-linked objects, Xalan would work forever analysing an infinite object tree. Even if your stylesheet was not constructed to process them all. It's because the current Xalan eagerly and extensively converts everything to its internal DTM model before further processing.

That's why there's a loop eliminator added that works by indexing every object-property combination during processing. If it notices that some object's property was already walked through, it doesn't go any deeper. Say you have two objects, x and y, with the following properties set (pseudocode): 

 x.y = y;
 and
 y.x = x;
 action.x=x;

Due to that modification, the resulting XML document based on x would be: 

 <result>
   <x>
     <y/>
   </x>
 </result>

Without it there would be endless x/y/x/y/x/y/... elements.

The XSLTResult code tries also to deal with the fact that DTM model is built in a manner that children are processed before siblings. The result is that if there is object x that is both set in action's x property, and very deeply under action's a property then it would only appear under a, not under x. That's not what we expect, and that's why XSLTResult allows objects to repeat in various places to some extent.

Sometimes the object mesh is still very dense and you may notice that even though you have a relatively simple stylesheet, execution takes a tremendous amount of time. To help you to deal with that obstacle of Xalan, you may attach regexp filters to elements paths (xpath).

Note: In your .xsl file the root match must be named result.
This example will output the username by using getUsername on your action class: 

 <xsl:template match="result">
   <html>
   <body>
   Hello <xsl:value-of select="username"/> how are you?
   </body>
   </html>
 </xsl:template>

In the following example the XSLT result would only walk through action's properties without their childs. It would also skip every property that has "hugeCollection" in their name. Element's path is first compared to excludingPattern - if it matches it's no longer processed. Then it is compared to matchingPattern and processed only if there's a match. 


 <result name="success" type="xslt">
   <param name="location">foo.xslt</param>
   <param name="matchingPattern">^/result/[^/*]$</param>
   <param name="excludingPattern">.*(hugeCollection).*</param>
 </result>

In the following example the XSLT result would use the action's user property instead of the action as it's base document and walk through it's properties. The exposedValue uses an ognl expression to derive it's value. 

 <result name="success" type="xslt">
   <param name="location">foo.xslt</param>
   <param name="exposedValue">user$</param>
 </result>
* This result type takes the following parameters:

struts.properties related configuration:

Example: 

 <result name="success" type="xslt">foo.xslt</result>

See Also:
Serialized Form

Field Summary
private  AdapterFactory adapterFactory
           
static String DEFAULT_PARAM
          'stylesheetLocation' parameter.
private  String excludingPattern
          Indicates the property name patterns which should be excluded from the xml.
private  String exposedValue
          Indicates the ognl expression respresenting the bean which is to be exposed as xml.
private static Logger LOG
          Log instance for this result.
private  String matchingPattern
          Indicates the property name patterns which should be exposed to the xml.
protected  boolean noCache
          Determines whether or not the result should allow caching.
private  boolean parse
           
private static long serialVersionUID
           
private  String stylesheetLocation
          Indicates the location of the xsl template.
private static Map<String,Templates> templatesCache
          Cache of all tempaltes.
 
Constructor Summary
XSLTResult()
           
XSLTResult(String stylesheetLocation)
           
 
Method Summary
 void execute(ActionInvocation invocation)
          Represents a generic interface for all action execution results.
protected  AdapterFactory getAdapterFactory()
           
protected  Source getDOMSourceForStack(Object value)
           
 String getExcludingPattern()
          Deprecated. Since 2.1.1
 String getExposedValue()
           
 String getMatchingPattern()
          Deprecated. Since 2.1.1
 String getStylesheetLocation()
           
protected  Templates getTemplates(String path)
           
protected  URIResolver getURIResolver()
          Get the URI Resolver to be called by the processor when it encounters an xsl:include, xsl:import, or document() function.
protected  void setAdapterFactory(AdapterFactory adapterFactory)
           
 void setExcludingPattern(String excludingPattern)
          Deprecated. Since 2.1.1
 void setExposedValue(String exposedValue)
           
 void setLocation(String location)
          Deprecated. Use #setStylesheetLocation(String)
 void setMatchingPattern(String matchingPattern)
          Deprecated. Since 2.1.1
 void setNoCache(String val)
           
 void setParse(boolean parse)
          If true, parse the stylesheet location for OGNL expressions.
 void setStylesheetLocation(String location)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

serialVersionUID

private static final long serialVersionUID
See Also:
Constant Field Values

LOG

private static final Logger LOG
Log instance for this result.

DEFAULT_PARAM

public static final String DEFAULT_PARAM
'stylesheetLocation' parameter. Points to the xsl.

See Also:
Constant Field Values

templatesCache

private static final Map<String,Templates> templatesCache
Cache of all tempaltes.

noCache

protected boolean noCache
Determines whether or not the result should allow caching.

stylesheetLocation

private String stylesheetLocation
Indicates the location of the xsl template.

matchingPattern

private String matchingPattern
Indicates the property name patterns which should be exposed to the xml.

excludingPattern

private String excludingPattern
Indicates the property name patterns which should be excluded from the xml.

exposedValue

private String exposedValue
Indicates the ognl expression respresenting the bean which is to be exposed as xml.

parse

private boolean parse

adapterFactory

private AdapterFactory adapterFactory
Constructor Detail

XSLTResult

public XSLTResult()

XSLTResult

public XSLTResult(String stylesheetLocation)
Method Detail

setNoCache

public void setNoCache(String val)

setLocation

public void setLocation(String location)
Deprecated. Use #setStylesheetLocation(String)

setStylesheetLocation

public void setStylesheetLocation(String location)

getStylesheetLocation

public String getStylesheetLocation()

getExposedValue

public String getExposedValue()

setExposedValue

public void setExposedValue(String exposedValue)

getMatchingPattern

public String getMatchingPattern()
Deprecated. Since 2.1.1

setMatchingPattern

public void setMatchingPattern(String matchingPattern)
Deprecated. Since 2.1.1

getExcludingPattern

public String getExcludingPattern()
Deprecated. Since 2.1.1

setExcludingPattern

public void setExcludingPattern(String excludingPattern)
Deprecated. Since 2.1.1

setParse

public void setParse(boolean parse)
If true, parse the stylesheet location for OGNL expressions.

Parameters:
parse -

execute

public void execute(ActionInvocation invocation)
             throws Exception
Description copied from interface: Result
Represents a generic interface for all action execution results. Whether that be displaying a webpage, generating an email, sending a JMS message, etc.

Specified by:
execute in interface Result
Parameters:
invocation - the invocation context.
Throws:
Exception - can be thrown.

getAdapterFactory

protected AdapterFactory getAdapterFactory()

setAdapterFactory

protected void setAdapterFactory(AdapterFactory adapterFactory)

getURIResolver

protected URIResolver getURIResolver()
Get the URI Resolver to be called by the processor when it encounters an xsl:include, xsl:import, or document() function. The default is an instance of ServletURIResolver, which operates relative to the servlet context.

getTemplates

protected Templates getTemplates(String path)
                          throws TransformerException,
                                 IOException
Throws:
TransformerException
IOException

getDOMSourceForStack

protected Source getDOMSourceForStack(Object value)
                               throws IllegalAccessException,
                                      InstantiationException
Throws:
IllegalAccessException
InstantiationException
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