log4j-core/src/main/java/org/apache/logging/log4j/core/pattern/ExtendedThrowablePatternConverter.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.logging.log4j.core.pattern;

import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.plugins.Plugin;
import org.apache.logging.log4j.core.impl.ThrowableProxy;

/**
 * Outputs the Throwable portion of the LoggingEvent as a full stack trace
 * unless this converter's option is 'short', where it just outputs the first line of the trace, or if
 * the number of lines to print is explicitly specified.
 * <p>
 * The extended stack trace will also include the location of where the class was loaded from and the
 * version of the jar if available.
 */
@Plugin(name = "ExtendedThrowablePatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys({ "xEx", "xThrowable", "xException" })
public final class ExtendedThrowablePatternConverter extends ThrowablePatternConverter {

    /**
     * Private constructor.
     *
     * @param config
     * @param options options, may be null.
     */
    private ExtendedThrowablePatternConverter(final Configuration config, final String[] options) {
        super("ExtendedThrowable", "throwable", options, config);
    }

    /**
     * Gets an instance of the class.
     *
     * @param config The current Configuration.
     * @param options pattern options, may be null.  If first element is "short",
     *                only the first line of the throwable will be formatted.
     * @return instance of class.
     */
    public static ExtendedThrowablePatternConverter newInstance(final Configuration config, final String[] options) {
        return new ExtendedThrowablePatternConverter(config, options);
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void format(final LogEvent event, final StringBuilder toAppendTo) {
        final ThrowableProxy proxy = event.getThrownProxy();
        final Throwable throwable = event.getThrown();
        if ((throwable != null || proxy != null) && options.anyLines()) {
            if (proxy == null) {
                super.format(event, toAppendTo);
                return;
            }
            final int len = toAppendTo.length();
            if (len > 0 && !Character.isWhitespace(toAppendTo.charAt(len - 1))) {
                toAppendTo.append(' ');
            }
            proxy.formatExtendedStackTraceTo(toAppendTo, options.getIgnorePackages(),
                    options.getTextRenderer(), getSuffix(event), options.getSeparator());
        }
    }

}