SAXLoggingErrorHandler.java

/*
 * Copyright (c) 2011, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
 *
 * 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.
 */

package org.wso2.carbon.humantask.core.utils;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

/**
 * An <code>ErrorHandler</code> implementation that dumps all of the error
 * messages onto a logging channel at the debug level.
 */
public class SAXLoggingErrorHandler implements ErrorHandler {

    private static final Log defaultLog = LogFactory.getLog(SAXLoggingErrorHandler.class);
    private Log log;

    private static final String WARNING = "WARNING";
    private static final String ERROR = "ERROR";
    private static final String FATAL = "FATAL";

    /**
     * Construct a new instance that dumps messages onto the default logging
     * channel defined by this class.
     */
    public SAXLoggingErrorHandler() {
        log = defaultLog;
    }

    /**
     * Construct a new instance that dumps messages onto a specific logging
     * channel.
     *
     * @param log the <code>Log</code> on which to dump messages.
     */
    public SAXLoggingErrorHandler(Log log) {
        this.log = log;
    }

    /**
     * @see org.xml.sax.ErrorHandler#warning(org.xml.sax.SAXParseException)
     */
    public void warning(SAXParseException exception) throws SAXException {
        if (log.isDebugEnabled()) {
            log.debug(formatMessage(WARNING, exception));
        }
    }

    /**
     * @see org.xml.sax.ErrorHandler#error(org.xml.sax.SAXParseException)
     */
    public void error(SAXParseException exception) throws SAXException {
        if (log.isDebugEnabled()) {
            log.debug(formatMessage(ERROR, exception));
        }
    }

    /**
     * @see org.xml.sax.ErrorHandler#fatalError(org.xml.sax.SAXParseException)
     */
    public void fatalError(SAXParseException exception) throws SAXException {
        if (log.isDebugEnabled()) {
            log.debug(formatMessage(FATAL, exception));
        }
    }

    private String formatMessage(String level, SAXParseException spe) {
        StringBuffer sb = new StringBuffer(64);

        if (spe.getSystemId() != null) {
            sb.append(spe.getSystemId());
        }

        sb.append(':');
        sb.append(spe.getLineNumber());
        sb.append(':');
        sb.append(spe.getColumnNumber());
        sb.append(':');
        sb.append(level);
        sb.append(':');
        sb.append(spe.getMessage());

        return sb.toString();
    }

}