001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.log4j;
018
019import org.apache.log4j.spi.ThrowableRenderer;
020
021import java.io.StringWriter;
022import java.io.PrintWriter;
023import java.io.LineNumberReader;
024import java.io.StringReader;
025import java.io.IOException;
026import java.io.InterruptedIOException;
027import java.util.ArrayList;
028
029/**
030 * Default implementation of ThrowableRenderer using
031 * Throwable.printStackTrace.
032 *
033 * @since 1.2.16
034 */
035public final class DefaultThrowableRenderer implements ThrowableRenderer {
036    /**
037     * Construct new instance.
038     */
039    public DefaultThrowableRenderer() {
040
041    }
042
043
044    /**
045     * {@inheritDoc}
046     */
047    public String[] doRender(final Throwable throwable) {
048        return render(throwable);
049    }
050
051    /**
052     * Render throwable using Throwable.printStackTrace.
053     * @param throwable throwable, may not be null.
054     * @return string representation.
055     */
056    public static String[] render(final Throwable throwable) {
057        StringWriter sw = new StringWriter();
058        PrintWriter pw = new PrintWriter(sw);
059        try {
060            throwable.printStackTrace(pw);
061        } catch(RuntimeException ex) {
062        }
063        pw.flush();
064        LineNumberReader reader = new LineNumberReader(
065                new StringReader(sw.toString()));
066        ArrayList lines = new ArrayList();
067        try {
068          String line = reader.readLine();
069          while(line != null) {
070            lines.add(line);
071            line = reader.readLine();
072          }
073        } catch(IOException ex) {
074            if (ex instanceof InterruptedIOException) {
075                Thread.currentThread().interrupt();
076            }
077            lines.add(ex.toString());
078        }
079        String[] tempRep = new String[lines.size()];
080        lines.toArray(tempRep);
081        return tempRep;
082    }
083}