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 */ 017 package org.apache.logging.log4j.core.pattern; 018 019 import org.apache.logging.log4j.core.LogEvent; 020 import org.apache.logging.log4j.core.config.plugins.Plugin; 021 022 import java.io.PrintWriter; 023 import java.io.StringWriter; 024 025 026 /** 027 * Outputs the Throwable portion of the LoggingEvent as a full stacktrace 028 * unless this converter's option is 'short', where it just outputs the first line of the trace, or if 029 * the number of lines to print is explicitly specified. 030 */ 031 @Plugin(name = "ThrowablePatternConverter", type = "Converter") 032 @ConverterKeys({"ex", "throwable", "exception" }) 033 public class ThrowablePatternConverter extends LogEventPatternConverter { 034 035 /** 036 * Do not format the exception. 037 */ 038 protected static final String NONE = "none"; 039 /** 040 * Format the whole stack trace. 041 */ 042 protected static final String FULL = "full"; 043 /** 044 * Format only the first line of the throwable. 045 */ 046 protected static final String SHORT = "short"; 047 /** 048 * If "short", only first line of throwable report will be formatted.<br> 049 * If "full", the whole stack trace will be formatted.<br> 050 * If "numeric" the output will be limited to the specified number of lines. 051 */ 052 protected final String option; 053 054 /** 055 * The number of lines to write. 056 */ 057 protected final int lines; 058 059 /** 060 * Constructor. 061 * @param name Name of converter. 062 * @param style CSS style for output. 063 * @param options options, may be null. 064 */ 065 protected ThrowablePatternConverter(final String name, final String style, final String[] options) { 066 super(name, style); 067 int count = Integer.MAX_VALUE; 068 if (options != null && options.length > 0) { 069 option = options[0]; 070 if (option == null) { 071 } else if (option.equalsIgnoreCase(NONE)) { 072 count = 0; 073 } else if (option.equalsIgnoreCase(SHORT)) { 074 count = 2; 075 } else if (!option.equalsIgnoreCase(FULL)) { 076 count = Integer.parseInt(option); 077 } 078 079 } else { 080 option = null; 081 } 082 lines = count; 083 } 084 085 /** 086 * Gets an instance of the class. 087 * 088 * @param options pattern options, may be null. If first element is "short", 089 * only the first line of the throwable will be formatted. 090 * @return instance of class. 091 */ 092 public static ThrowablePatternConverter newInstance(final String[] options) { 093 return new ThrowablePatternConverter("Throwable", "throwable", options); 094 } 095 096 /** 097 * {@inheritDoc} 098 */ 099 @Override 100 public void format(final LogEvent event, final StringBuilder toAppendTo) { 101 final Throwable t = event.getThrown(); 102 103 if (t != null && lines > 0) { 104 final StringWriter w = new StringWriter(); 105 t.printStackTrace(new PrintWriter(w)); 106 final int len = toAppendTo.length(); 107 if (len > 0 && !Character.isWhitespace(toAppendTo.charAt(len - 1))) { 108 toAppendTo.append(" "); 109 } 110 if (lines != Integer.MAX_VALUE) { 111 final StringBuilder sb = new StringBuilder(); 112 final String[] array = w.toString().split("\n"); 113 final int limit = lines > array.length ? array.length : lines; 114 for (int i = 0; i < limit; ++i) { 115 sb.append(array[i]).append("\n"); 116 } 117 toAppendTo.append(sb.toString()); 118 119 } else { 120 toAppendTo.append(w.toString()); 121 } 122 } 123 } 124 125 /** 126 * This converter obviously handles throwables. 127 * 128 * @return true. 129 */ 130 @Override 131 public boolean handlesThrowable() { 132 return true; 133 } 134 }