src/java/org/apache/log4j/xml/XMLLayout.java

/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software
 * License version 1.1, a copy of which has been included with this
 * distribution in the LICENSE.txt file.  */

// Contributors:   Mathias Bogaert

package org.apache.log4j.xml;

import org.apache.log4j.Layout;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.LocationInfo;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.helpers.DateLayout;
import org.apache.log4j.helpers.Transform;

/**
 * The output of the XMLLayout consists of a series of log4j:event
 * elements as defined in the <a
 * href="doc-files/log4j.dtd">log4j.dtd</a>. It does not output a
 * complete well-formed XML file. The output is designed to be
 * included as an <em>external entity</em> in a separate file to form
 * a correct XML file.
 *
 * <p>For example, if <code>abc</code> is the name of the file where
 * the XMLLayout ouput goes, then a well-formed XML file would be:
 *
  <pre>
   &lt;?xml version="1.0" ?&gt;
 
  &lt;!DOCTYPE log4j:eventSet SYSTEM "log4j.dtd" [&lt;!ENTITY data SYSTEM "abc"&gt;]&gt;
 
  &lt;log4j:eventSet version="1.2" xmlns:log4j="http://jakarta.apache.org/log4j/"&gt;
 	&nbsp;&nbsp;&data;
  &lt;/log4j:eventSet&gt;
  </pre>
 
 * <p>This approach enforces the independence of the XMLLayout and the
 * appender where it is embedded.
 *
 * <p>The <code>version</code> attribute helps components to correctly
 * intrepret output generated by XMLLayout. The value of this
 * attribute should be "1.1" for output generated by log4j versions
 * prior to log4j 1.2 (final release) and "1.2" for relase 1.2 and
 * later.
 *
 * @author Ceki  G&uuml;lc&uuml;
 * @since 0.9.0 
 * */
public class XMLLayout extends Layout {

  private  final int DEFAULT_SIZE = 256;
  private final int UPPER_LIMIT = 2048;

  private StringBuffer buf = new StringBuffer(DEFAULT_SIZE);
  private boolean locationInfo = false;
 
  /**
   * The <b>LocationInfo</b> option takes a boolean value. By default,
   * it is set to false which means there will be no location
   * information output by this layout. If the the option is set to
   * true, then the file name and line number of the statement at the
   * origin of the log statement will be output.
   *
   * <p>If you are embedding this layout within an {@link
   * org.apache.log4j.net.SMTPAppender} then make sure to set the
   * <b>LocationInfo</b> option of that appender as well.
   * */
  public void setLocationInfo(boolean flag) {
    locationInfo = flag;
  }
  
  /**
     Returns the current value of the <b>LocationInfo</b> option.
   */
  public boolean getLocationInfo() {
    return locationInfo;
  }
  
  /** No options to activate. */
  public void activateOptions() {
  }


  /**
   * Formats a {@link LoggingEvent} in conformance with the log4j.dtd.
   * */
  public String format(LoggingEvent event) {

    // Reset working buffer. If the buffer is too large, then we need a new
    // one in order to avoid the penalty of creating a large array.
    if(buf.capacity() > UPPER_LIMIT) {
      buf = new StringBuffer(DEFAULT_SIZE);
    } else {
      buf.setLength(0);
    }
    
    // We yield to the \r\n heresy.

    buf.append("<log4j:event logger=\"");
    buf.append(event.getLoggerName());
    buf.append("\" timestamp=\"");
    buf.append(event.timeStamp);
    buf.append("\" level=\"");
    buf.append(event.getLevel());
    buf.append("\" thread=\"");
    buf.append(event.getThreadName());
    buf.append("\">\r\n");

    buf.append("<log4j:message><![CDATA[");
    // Append the rendered message. Also make sure to escape any
    // existing CDATA sections.
    Transform.appendEscapingCDATA(buf, event.getRenderedMessage());
    buf.append("]]></log4j:message>\r\n");       
    
    String ndc = event.getNDC();
    if(ndc != null) {
      buf.append("<log4j:NDC><![CDATA[");
      buf.append(ndc);
      buf.append("]]></log4j:NDC>\r\n");       
    }
    
    String[] s = event.getThrowableStrRep();
    if(s != null) {
      buf.append("<log4j:throwable><![CDATA[");
      for(int i = 0; i < s.length; i++) {
	buf.append(s[i]);
	buf.append("\r\n");
      }
      buf.append("]]></log4j:throwable>\r\n");
    }
    
    if(locationInfo) { 
      LocationInfo locationInfo = event.getLocationInformation();	
      buf.append("<log4j:locationInfo class=\"");
      buf.append(locationInfo.getClassName());
      buf.append("\" method=\"");
      buf.append(Transform.escapeTags(locationInfo.getMethodName()));
      buf.append("\" file=\"");
      buf.append(locationInfo.getFileName());
      buf.append("\" line=\"");
      buf.append(locationInfo.getLineNumber());
      buf.append("\"/>\r\n");
    }
    
    buf.append("</log4j:event>\r\n\r\n");
    
    return buf.toString();
  }
  
  /**
     The XMLLayout prints and does not ignore exceptions. Hence the
     return value <code>false</code>.
  */
  public boolean ignoresThrowable() {
    return false;
  }
}