XSLT Caching

Question

HI,
I am using JAXP Template object to cache my XSLT files. Can my code pass parameters to a cached XSLT file?
Thanks,
Java-Junkie

Answer 1

I am using the following code to handle my transforms, can you suggest how I would cache the xslt files?
import javax.xml.transform.*;
import javax.xml.transform.stream.*;
import java.util.*;
import java.io.*;
public class TransformerPool
/** Source control version number. */
public final static String SOURCE_VERSION_INFO = "%R%";
/** Minimum number of transformers per transformation. */
public final static int MIN_INSTANCES = 1;
/** Maximum number of transformers per transformation. */
public final static int MAX_INSTANCES = 5;
// class members
private static TransformerFactory tFactory;
private static TransformerPool thisTP;
// data members
private Map transformers;
private int defaultMinInstances;
private int defaultMaxInstances;
private class PoolEntry
private int minInstances;
private int maxInstances;
private int currentInstances;
private int hits;
private int waitStates;
private int waitIter;
private StreamSource xslDocument;
private boolean busy[];
private Transformer processors[];
public PoolEntry(TransformerPool source, String xslDocument)
init(source);
initTransformer(xslDocument);
public PoolEntry(TransformerPool source, StreamSource streamSource)
init(source);
initTransformer(streamSource);
public void init(TransformerPool source)
minInstances = source.defaultMinInstances;
maxInstances = source.defaultMaxInstances;
currentInstances = minInstances;
hits = 0;
waitStates = 0;
waitIter = 0;
public void initTransformer(String xslDocument)
initTransformer(new StreamSource(new StringReader(xslDocument)));
public void initTransformer(StreamSource xslDocument)
this.xslDocument = xslDocument;
busy = new boolean[maxInstances];
processors = new Transformer[maxInstances];
for ( int i=0; i<maxInstances; i++ )
busy[i] = false;
processors[i] = i < currentInstances ? newTransformer() : null;
private Transformer newTransformer()
synchronized (TransformerPool.tFactory)
try
Templates cashedXSLT = TransformerPool.tFactory.newTemplates(xslDocument);
Transformer trans = cashedXSLT.newTransformer();
return trans;
//return TransformerPool.tFactory.newTransformer(xslDocument);
catch (TransformerConfigurationException e)
return null;
public boolean transform(Source xml, Result result, Properties params)
boolean isBusy = false;
boolean allNull = false;
Transformer xform = null;
int index = -1;
do
if (isBusy)
try
Thread.currentThread().sleep(100);
catch (InterruptedException e)
synchronized (this)
allNull = true;
for ( int i=0; i<maxInstances; i++ )
if (processors[i] != null)
allNull = false;
if (processors[i] != null && busy[i] == false)
index = i;
xform = processors;
busy[i] = true;
isBusy = false;
break;
if (allNull == true) // theres nothing we can do; fail
return false;
if (index == -1)
waitIter++;
isBusy = true;
} while (isBusy);
// we should have a transformer now
try
String paramName;
xform.clearParameters();
if(params!=null){
for ( Enumeration e=params.propertyNames(); e.hasMoreElements(); )
paramName = (String)e.nextElement();
xform.setParameter(paramName, params.get(paramName));
Message.out(Message.DEBUG, "starting transform");
xform.transform(xml, result);
Message.out(Message.DEBUG, "ending transform");
catch (Exception e)
e.printStackTrace();
Message.out(Message.DEBUG, "exception? " + e.toString());
return false;
finally
if (xform != null)
synchronized (this)
busy[index] = false;
// increment counters
if (isBusy)
waitStates++;
hits++;
return true;
* Create a new {@link TransformerPool}.
private TransformerPool()
if (tFactory == null)
tFactory = TransformerFactory.newInstance();
transformers = new HashMap();
defaultMinInstances = MIN_INSTANCES;
defaultMaxInstances = MAX_INSTANCES;
* Create a new {@link TransformerPool}.
* @return A {@link TransformerPool} instance.
public static synchronized TransformerPool getInstance()
if (thisTP == null)
thisTP = new TransformerPool();
return thisTP;
private synchronized PoolEntry newEntry(StreamSource xsl)
return xsl == null ? null : new PoolEntry(this, xsl);
public synchronized void dump(PrintWriter out)
PoolEntry entry;
String key;
out.println("Default instances: " + defaultMinInstances +
" (minimum), " + defaultMaxInstances + " (maximum)");
out.println("Transfomers: " + transformers.size());
out.println();
for ( Iterator iter=transformers.keySet().iterator(); iter.hasNext(); )
key = (String)iter.next();
entry = (PoolEntry)transformers.get(key);
out.println("Transformer: " + key);
out.println(" Instances: " + entry.minInstances + " (minimum), " +
entry.maxInstances + " (maximum), " + entry.currentInstances +
" (current)");
out.println(" Hits: " + entry.hits + " (" + entry.waitStates + " busy)");
for ( int i=0; i<entry.maxInstances; i++ )
out.println(" (" + i + ") " + entry.processors[i] + " " + (entry.busy[i] ? "busy" : "not busy"));
out.println();
out.flush();
* Add a new transformation.
* @param name Transformation name as a String.
* @param xsl Transformation XSLT document as a StreamSource.
public synchronized void addTransformation(String name, StreamSource xsl)
PoolEntry entry = newEntry(xsl);
if (entry != null)
transformers.put(name, entry);
* Remove a given transformation.
* @param name Transformation name as a String.
public synchronized void removeTransformation(String name)
transformers.remove(name);
* Determines if a given transformation exists.
* @param name Transformation name as a String.
* @return <code>true</code> if there is a transformation by that
* name, otherwise <code>false</code>.
public synchronized boolean isTransformation(String name)
return transformers.containsKey(name);
* Transform an XML document using a named transformation.
* @param name Transformation name as a String.
* @param xml XML document to transform as a Source.
* @param result Transformed document as a Result.
* @return <code>true</code> if the transformation succeeded or
* <code>false</code> if the transformation couldn't be completed
* for any reason.
public synchronized boolean transform(String name, Source xml, Result result)
// find the entry
PoolEntry entry = (PoolEntry)transformers.get(name);
if (entry == null)
return false;
// transform
return entry.transform(xml, result, null);
* Transform an XML document using a named transformation.
* @param name Transformation name as a String.
* @param xml XML document to transform as a Source.
* @param result Transformed document as a Result.
* @param params Collection of transformation parameters as Properties.
* @return <code>true</code> if the transformation succeeded or
* <code>false</code> if the transformation couldn't be completed
* for any reason.
public synchronized boolean transform(String name, Source xml, Result result, Properties params)
// find the entry
PoolEntry entry = (PoolEntry)transformers.get(name);
if (entry == null)
return false;
// transform
return entry.transform(xml, result, params);