listingerrorhandler.java

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/*
 * Copyright 2000-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: ListingErrorHandler.java,v 1.2.4.1 2005/09/15 08:15:46 suresh_emailid Exp $
 */

package com.sun.org.apache.xml.internal.utils;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.URL;
import java.net.URLConnection;

import javax.xml.transform.ErrorListener;
import javax.xml.transform.SourceLocator;
import javax.xml.transform.TransformerException;

import com.sun.org.apache.xml.internal.res.XMLErrorResources;
import com.sun.org.apache.xml.internal.res.XMLMessages;

import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;


/**
 * Sample implementation of similar SAX ErrorHandler and JAXP ErrorListener.  
 *
 * <p>This implementation is suitable for various use cases, and 
 * provides some basic configuration API's as well to control 
 * when we re-throw errors, etc.</p>
 *
 * @author [e-mail]
 * @version $Id: ListingErrorHandler.java,v 1.2.4.1 2005/09/15 08:15:46 suresh_emailid Exp $
 * @xsl.usage general
 */
public class ListingErrorHandler implements ErrorHandler, ErrorListener
{
    protected PrintWriter m_pw = null;
  

    /**
     * Constructor ListingErrorHandler; user-supplied PrintWriter.  
     */
    public ListingErrorHandler(PrintWriter pw)
    {
        if (null == pw)
            throw new NullPointerException(XMLMessages.createXMLMessage(XMLErrorResources.ER_ERRORHANDLER_CREATED_WITH_NULL_PRINTWRITER, null));
            // "ListingErrorHandler created with null PrintWriter!");
            
        m_pw = pw;
    }

    /**
     * Constructor ListingErrorHandler; uses System.err.  
     */
    public ListingErrorHandler()
    {
        m_pw = new PrintWriter(System.err, true);
    }


    /* ======== Implement org.xml.sax.ErrorHandler ======== */
    /**
     * Receive notification of a warning.
     *
     * <p>SAX parsers will use this method to report conditions that
     * are not errors or fatal errors as defined by the XML 1.0
     * recommendation.  The default behaviour is to take no action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing events
     * after invoking this method: it should still be possible for the
     * application to process the document through to the end.</p>
     *
     * <p>Filters may use this method to report other, non-XML warnings
     * as well.</p>
     *
     * @param exception The warning information encapsulated in a
     *                  SAX parse exception.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     * wrapping another exception; only if setThrowOnWarning is true.
     * @see org.xml.sax.SAXParseException 
     */
    public void warning (SAXParseException exception)
    	throws SAXException
    {
    	logExceptionLocation(m_pw, exception);
        // Note: should we really call .toString() below, since 
        //  sometimes the message is not properly set?
        m_pw.println("warning: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnWarning())
            throw exception;
    }
    
    
    /**
     * Receive notification of a recoverable error.
     *
     * <p>This corresponds to the definition of "error" in section 1.2
     * of the W3C XML 1.0 Recommendation.  For example, a validating
     * parser would use this callback to report the violation of a
     * validity constraint.  The default behaviour is to take no
     * action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing events
     * after invoking this method: it should still be possible for the
     * application to process the document through to the end.  If the
     * application cannot do so, then the parser should report a fatal
     * error even if the XML 1.0 recommendation does not require it to
     * do so.</p>
     *
     * <p>Filters may use this method to report other, non-XML errors
     * as well.</p>
     *
     * @param exception The error information encapsulated in a
     *                  SAX parse exception.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     * wrapping another exception; only if setThrowOnErroris true.
     * @see org.xml.sax.SAXParseException 
     */
    public void error (SAXParseException exception)
    	throws SAXException
    {
    	logExceptionLocation(m_pw, exception);
        m_pw.println("error: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnError())
            throw exception;
    }
    
    
    /**
     * Receive notification of a non-recoverable error.
     *
     * <p>This corresponds to the definition of "fatal error" in
     * section 1.2 of the W3C XML 1.0 Recommendation.  For example, a
     * parser would use this callback to report the violation of a
     * well-formedness constraint.</p>
     *
     * <p>The application must assume that the document is unusable
     * after the parser has invoked this method, and should continue
     * (if at all) only for the sake of collecting addition error
     * messages: in fact, SAX parsers are free to stop reporting any
     * other events once this method has been invoked.</p>
     *
     * @param exception The error information encapsulated in a
     *                  SAX parse exception.  
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     * wrapping another exception; only if setThrowOnFatalError is true.
     * @see org.xml.sax.SAXParseException
     */
    public void fatalError (SAXParseException exception)
    	throws SAXException
    {
    	logExceptionLocation(m_pw, exception);
        m_pw.println("fatalError: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnFatalError())
            throw exception;
    }


    /* ======== Implement javax.xml.transform.ErrorListener ======== */

    /**
     * Receive notification of a warning.
     *
     * <p>{@link javax.xml.transform.Transformer} can use this method to report
     * conditions that are not errors or fatal errors.  The default behaviour
     * is to take no action.</p>
     *
     * <p>After invoking this method, the Transformer must continue with
     * the transformation. It should still be possible for the
     * application to process the document through to the end.</p>
     *
     * @param exception The warning information encapsulated in a
     *                  transformer exception.
     *
     * @throws javax.xml.transform.TransformerException  only if 
     * setThrowOnWarning is true.
     *
     * @see javax.xml.transform.TransformerException
     */
    public void warning(TransformerException exception)
        throws TransformerException
    {
    	logExceptionLocation(m_pw, exception);
        m_pw.println("warning: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnWarning())
            throw exception;
    }

    /**
     * Receive notification of a recoverable error.
     *
     * <p>The transformer must continue to try and provide normal transformation
     * after invoking this method.  It should still be possible for the
     * application to process the document through to the end if no other errors
     * are encountered.</p>
     *
     * @param exception The error information encapsulated in a
     *                  transformer exception.
     *
     * @throws javax.xml.transform.TransformerException  only if 
     * setThrowOnError is true.
     *
     * @see javax.xml.transform.TransformerException
     */
    public void error(TransformerException exception)
        throws TransformerException
    {
    	logExceptionLocation(m_pw, exception);
        m_pw.println("error: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnError())
            throw exception;
    }

    /**
     * Receive notification of a non-recoverable error.
     *
     * <p>The transformer must continue to try and provide normal transformation
     * after invoking this method.  It should still be possible for the
     * application to process the document through to the end if no other errors
     * are encountered, but there is no guarantee that the output will be
     * useable.</p>
     *
     * @param exception The error information encapsulated in a
     *                  transformer exception.
     *
     * @throws javax.xml.transform.TransformerException  only if 
     * setThrowOnError is true.
     *
     * @see javax.xml.transform.TransformerException
     */
    public void fatalError(TransformerException exception)
        throws TransformerException
    {
    	logExceptionLocation(m_pw, exception);
        m_pw.println("error: " + exception.getMessage());
        m_pw.flush();

        if (getThrowOnError())
            throw exception;
    }



    /* ======== Implement worker methods ======== */


    /**
     * Print out location information about the exception.  
     *
     * Cribbed from DefaultErrorHandler.printLocation() 
     * @param pw PrintWriter to send output to
     * @param exception TransformerException or SAXParseException
     * to log information about
     */
    public static void logExceptionLocation(PrintWriter pw, Throwable exception)
    {