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    1   /*
    2    * Licensed to the Apache Software Foundation (ASF) under one or more
    3    * contributor license agreements. See the NOTICE file distributed with
    4    * this work for additional information regarding copyright ownership.
    5    * The ASF licenses this file to You under the Apache license, Version 2.0
    6    * (the "License"); you may not use this file except in compliance with
    7    * the License. You may obtain a copy of the License at
    8    *
    9    *      http://www.apache.org/licenses/LICENSE-2.0
    10   *
    11   * Unless required by applicable law or agreed to in writing, software
    12   * distributed under the License is distributed on an "AS IS" BASIS,
    13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    14   * See the license for the specific language governing permissions and
    15   * limitations under the license.
    16   */
    17  package org.apache.logging.log4j.core.pattern;
    18
    19  import java.io.PrintWriter;
    20  import java.io.StringWriter;
    21
    22  import org.apache.logging.log4j.core.LogEvent;
    23  import org.apache.logging.log4j.core.config.plugins.Plugin;
    24  import org.apache.logging.log4j.core.impl.ThrowableFormatOptions;
    25  import org.apache.logging.log4j.core.util.Constants;
    26  import org.apache.logging.log4j.util.Strings;
    27
    28
    29  /**
    30   * Outputs the Throwable portion of the LoggingEvent as a full stack trace
    31   * unless this converter's option is 'short', where it just outputs the first line of the trace, or if
    32   * the number of lines to print is explicitly specified.
    33   */
    34  @Plugin(name = "ThrowablePatternConverter", category = PatternConverter.CATEGORY)
    35  @ConverterKeys({ "ex", "throwable", "exception" })
    36  public class ThrowablePatternConverter extends LogEventPatternConverter {
    37
    38      private String rawOption;
    39
    40      /**
    41       * The number of lines to write.
    42       */
    43      protected final ThrowableFormatOptions options;
    44
    45      /**
    46       * Constructor.
    47       * @param name Name of converter.
    48       * @param style CSS style for output.
    49       * @param options options, may be null.
    50       */
    51      protected ThrowablePatternConverter(final String name, final String style, final String[] options) {
    52          super(name, style);
    53          this.options = ThrowableFormatOptions.newInstance(options);
    54          if (options != null && options.length > 0) {
    55              rawOption = options[0];
    56          }
    57      }
    58
    59      /**
    60       * Gets an instance of the class.
    61       *
    62       * @param options pattern options, may be null.  If first element is "short",
    63       *                only the first line of the throwable will be formatted.
    64       * @return instance of class.
    65       */
    66      public static ThrowablePatternConverter newInstance(final String[] options) {
    67          return new ThrowablePatternConverter("Throwable", "throwable", options);
    68      }
    69
    70      /**
    71       * {@inheritDoc}
    72       */
    73      @Override
    74      public void format(final LogEvent event, final StringBuilder buffer) {
    75          final Throwable t = event.getThrown();
    76
    77          if (isSubShortOption()) {
    78              formatSubShortOption(t, buffer);
    79          }
    80          else if (t != null && options.anyLines()) {
    81              formatOption(t, buffer);
    82          }
    83      }
    84
    85      private boolean isSubShortOption() {
    86          return ThrowableFormatOptions.MESSAGE.equalsIgnoreCase(rawOption) ||
    87                  ThrowableFormatOptions.LOCALIZED_MESSAGE.equalsIgnoreCase(rawOption) ||
    88                  ThrowableFormatOptions.FILE_NAME.equalsIgnoreCase(rawOption) ||
    89                  ThrowableFormatOptions.LINE_NUMBER.equalsIgnoreCase(rawOption) ||
    90                  ThrowableFormatOptions.METHOD_NAME.equalsIgnoreCase(rawOption) ||
    91                  ThrowableFormatOptions.CLASS_NAME.equalsIgnoreCase(rawOption);
    92      }
    93
    94      private void formatSubShortOption(final Throwable t, final StringBuilder buffer) {
    95          StackTraceElement[] trace;
    96          StackTraceElement throwingMethod = null;
    97          int len;
    98
    99          if (t != null) {
    100             trace = t.getStackTrace();
    101             if (trace !=null && trace.length > 0) {
    102                 throwingMethod = trace[0];
    103             }
    104         }
    105
    106         if (t != null && throwingMethod != null) {
    107             String toAppend = Strings.EMPTY;
    108
    109             if (ThrowableFormatOptions.CLASS_NAME.equalsIgnoreCase(rawOption)) {
    110                 toAppend = throwingMethod.getClassName();
    111             }
    112             else if (ThrowableFormatOptions.METHOD_NAME.equalsIgnoreCase(rawOption)) {
    113                 toAppend = throwingMethod.getMethodName();
    114             }
    115             else if (ThrowableFormatOptions.LINE_NUMBER.equalsIgnoreCase(rawOption)) {
    116                 toAppend = String.valueOf(throwingMethod.getLineNumber());
    117             }
    118             else if (ThrowableFormatOptions.MESSAGE.equalsIgnoreCase(rawOption)) {
    119                 toAppend = t.getMessage();
    120             }
    121             else if (ThrowableFormatOptions.LOCALIZED_MESSAGE.equalsIgnoreCase(rawOption)) {
    122                 toAppend = t.getLocalizedMessage();
    123             }
    124             else if (ThrowableFormatOptions.FILE_NAME.equalsIgnoreCase(rawOption)) {
    125                 toAppend = throwingMethod.getFileName();
    126             }
    127
    128             len = buffer.length();
    129             if (len > 0 && !Character.isWhitespace(buffer.charAt(len - 1))) {
    130                 buffer.append(' ');
    131             }
    132             buffer.append(toAppend);
    133         }
    134     }
    135
    136     private void formatOption(final Throwable throwable, final StringBuilder buffer) {
    137         final StringWriter w = new StringWriter();
    138
    139         throwable.printStackTrace(new PrintWriter(w));
    140         final int len = buffer.length();
    141         if (len > 0 && !Character.isWhitespace(buffer.charAt(len - 1))) {
    142             buffer.append(' ');
    143         }
    144         if (!options.allLines() || !Constants.LINE_SEPARATOR.equals(options.getSeparator())) {
    145             final StringBuilder sb = new StringBuilder();
    146             final String[] array = w.toString().split(Constants.LINE_SEPARATOR);
    147             final int limit = options.minLines(array.length) - 1;
    148             for (int i = 0; i <= limit; ++i) {
    149                 sb.append(array[i]);
    150                 if (i < limit) {
    151                     sb.append(options.getSeparator());
    152                 }
    153             }
    154             buffer.append(sb.toString());
    155
    156         } else {
    157             buffer.append(w.toString());
    158         }
    159     }
    160
    161     /**
    162      * This converter obviously handles throwables.
    163      *
    164      * @return true.
    165      */
    166     @Override
    167     public boolean handlesThrowable() {
    168         return true;
    169     }
    170 }