ErrorListener Example

import javax.xml.transform.*;
import java.util.logging.*;


public class LoggingErrorListener implements ErrorListener {

  private Logger logger;
  
  public LoggingErrorListener(Logger logger) {
    this.logger = logger;
  }
  
  public void warning(TransformerException exception) {
   
    logger.log(Level.WARNING, exception.getMessage(), exception);
   
    // Don't throw an exception and stop the processor
    // just for a warning; but do log the problem
  }
  
  public void error(TransformerException exception)
   throws TransformerException {
    
    logger.log(Level.SEVERE, exception.getMessage(), exception);
    // XSLT is not as draconian as XML. There are numerous errors
    // which the processor may but does not have to recover from; 
    // e.g. multiple templates that match a node with the same
    // priority. I do not want to allow that so I throw this 
    // exception here.
    throw exception;
    
  }
  
  public void fatalError(TransformerException exception)
   throws TransformerException {
    
    logger.log(Level.SEVERE, exception.getMessage(), exception);

    // This is an error which the processor cannot recover from; 
    // e.g. a malformed stylesheet or input document
    // so I must throw this exception here.
    throw exception;
    
  }
     
}

The following two methods appear in both TransformerFactory and Transformer. They enable you to set and get the ErrorListener that the object will report problems to:

An ErrorListener registered with a Transformer will report errors with the transformation. An ErrorListener registered with a TransformerFactory will report errors with the factory’s attempts to create new Transformer objects. For example, this code fragment installs separate LoggingErrorListeners on the TransformerFactory and the Transformer object it creates that will record messages in two different logs.

TransformerFactory factory = TransformerFactory.newInstance();
Logger factoryLogger 
 = Logger.getLogger("com.macfaq.trax.factory");
ErrorListener factoryListener 
 = new LoggingErrorListener(factoryLogger);
factory.setErrorListener(factoryListener);
Source source = new StreamSource("FibonacciXMLRPC.xsl");
Transformer stylesheet = factory.newTransformer(source);
Logger transformerLogger 
 = Logger.getLogger("com.macfaq.trax.transformer");
ErrorListener transformerListener 
 = new LoggingErrorListener(transformerLogger);
stylesheet.setErrorListener(transformerListener);