src/java/org/apache/log4j/HTMLLayout.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.  */

package org.apache.log4j;

import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.LocationInfo;
import org.apache.log4j.helpers.OptionConverter;
import java.io.StringWriter;
import java.io.PrintWriter;
import java.io.Writer;

/**
   This layout outputs events in a HTML table.

   @author Ceki Gülcü   
 */
public class HTMLLayout extends Layout {

  protected final int BUF_SIZE = 256;
  protected final int MAX_CAPACITY = 1024;

  static String TRACE_PREFIX = "<br>&nbsp;&nbsp;&nbsp;&nbsp;";

  // output buffer appended to when format() is invoked
  private StringBuffer sbuf = new StringBuffer(BUF_SIZE);

  /**
     A string constant used in naming the option for setting the the
     location information flag.  Current value of this string
     constant is <b>LocationInfo</b>.  

     <p>Note that all option keys are case sensitive.
     
     @deprecated Options are now handled using the JavaBeans paradigm.
     This constant is not longer needed and will be removed in the
     <em>near</em> term.

  */
  public static final String LOCATION_INFO_OPTION = "LocationInfo";

  /**
     A string constant used in naming the option for setting the the
     HTML document title.  Current value of this string
     constant is <b>Title</b>.  
  */
  public static final String TITLE_OPTION = "Title";

  // Print no location info by default
  boolean locationInfo = false;

  String title = "Log4J Log Messages";

  /**
     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;
  }

  /**
    The <b>Title</b> option takes a String value. This option sets the
    document title of the generated HTML document.
    
    <p>Defaults to 'Log4J Log Messages'.
  */
  public
  void setTitle(String title) {
    this.title = title;
  }

  /**
     Returns the current value of the <b>Title</b> option.
  */
  public
  String getTitle() {
    return title;
  }
  
 /**
     Returns the content type output by this layout, i.e "text/html".
  */
  public
  String getContentType() {
    return "text/html";
  }

  /**
     No options to activate.
  */
  public
  void activateOptions() {
  }
  
  public 
  String format(LoggingEvent event) {
    
    if(sbuf.capacity() > MAX_CAPACITY) {
      sbuf = new StringBuffer(BUF_SIZE);
    } else {
      sbuf.setLength(0);
    }
    
    sbuf.append(Layout.LINE_SEP + "<tr>" + Layout.LINE_SEP);
 
    sbuf.append("<td>");
    sbuf.append(event.timeStamp - event.getStartTime());
    sbuf.append("</td>" + Layout.LINE_SEP);

    sbuf.append("<td title=\"" + event.getThreadName() + " thread\">");
    sbuf.append(escapeHTMLTags(event.getThreadName()));
    sbuf.append("</td>" + Layout.LINE_SEP);

    sbuf.append("<td title=\"Level\">");
    if (event.level.equals(Level.DEBUG)) {
      sbuf.append("<font color=\"#339933\">");
      sbuf.append(event.level);      
      sbuf.append("</font>");
    }
    else if(event.level.isGreaterOrEqual(Level.WARN)) {
      sbuf.append("<font color=\"#993300\"><strong>");
      sbuf.append(event.level);      
      sbuf.append("</strong></font>");
    } else {
      sbuf.append(event.level);      
    }
    sbuf.append("</td>" + Layout.LINE_SEP);

    sbuf.append("<td title=\"" + event.categoryName + " category\">");
    sbuf.append(escapeHTMLTags(event.categoryName));
    sbuf.append("</td>" + Layout.LINE_SEP);

    if(locationInfo) {
      LocationInfo locInfo = event.getLocationInformation();
      sbuf.append("<td>");
      sbuf.append(escapeHTMLTags(locInfo.getFileName()));
      sbuf.append(':');
      sbuf.append(locInfo.getLineNumber());
      sbuf.append("</td>" + Layout.LINE_SEP);
    }

    sbuf.append("<td title=\"Message\">");
    sbuf.append(escapeHTMLTags(event.getRenderedMessage()));
    sbuf.append("</td>" + Layout.LINE_SEP);
    sbuf.append("</tr>" + Layout.LINE_SEP);

    if (event.getNDC() != null) {
      sbuf.append("<tr><td bgcolor=\"#EEEEEE\" style=\"font-size : xx-small;\" colspan=\"6\" title=\"Nested Diagnostic Context\">");
      sbuf.append("NDC: " + escapeHTMLTags(event.getNDC()));
      sbuf.append("</td></tr>" + Layout.LINE_SEP);
    }

    String[] s = event.getThrowableStrRep(); 
    if(s != null) {
      sbuf.append("<tr><td bgcolor=\"#993300\" style=\"color:White; font-size : xx-small;\" colspan=\"6\">");
      appendThrowableAsHTML(s, sbuf);
      sbuf.append("</td></tr>" + Layout.LINE_SEP);
    }

    return sbuf.toString();
  }

  void appendThrowableAsHTML(String[] s, StringBuffer sbuf) {
    if(s != null) {
      int len = s.length;
      if(len == 0) 
	return;
      sbuf.append(escapeHTMLTags(s[0]));
      sbuf.append(Layout.LINE_SEP);
      for(int i = 1; i < len; i++) {
	sbuf.append(TRACE_PREFIX);
	sbuf.append(escapeHTMLTags(s[i]));
	sbuf.append(Layout.LINE_SEP);
      }
    }
  }

  /**
     Returns appropriate HTML headers.
  */
  public
  String getHeader() {
    StringBuffer sbuf = new StringBuffer();
    sbuf.append("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">"  + Layout.LINE_SEP);
    sbuf.append("<html>" + Layout.LINE_SEP);
    sbuf.append("<head>" + Layout.LINE_SEP);
    sbuf.append("<title>" + title + "</title>" + Layout.LINE_SEP);
    sbuf.append("<style type=\"text/css\">"  + Layout.LINE_SEP);
    sbuf.append("<!--"  + Layout.LINE_SEP);
    sbuf.append("body, table {font-family: arial,sans-serif; font-size: x-small;}" + Layout.LINE_SEP);
    sbuf.append("th {background: #336699; color: #FFFFFF; text-align: left;}" + Layout.LINE_SEP);
    sbuf.append("-->" + Layout.LINE_SEP);
    sbuf.append("</style>" + Layout.LINE_SEP);
    sbuf.append("</head>" + Layout.LINE_SEP);
    sbuf.append("<body bgcolor=\"#FFFFFF\" topmargin=\"6\" leftmargin=\"6\">" + Layout.LINE_SEP);
    sbuf.append("<hr size=\"1\" noshade>" + Layout.LINE_SEP);
    sbuf.append("Log session start time " + new java.util.Date() + "<br>" + Layout.LINE_SEP);
    sbuf.append("<br>" + Layout.LINE_SEP);
    sbuf.append("<table cellspacing=\"0\" cellpadding=\"4\" border=\"1\" bordercolor=\"#224466\" width=\"100%\">" + Layout.LINE_SEP);
    sbuf.append("<tr>" + Layout.LINE_SEP);
    sbuf.append("<th>Time</th>" + Layout.LINE_SEP);
    sbuf.append("<th>Thread</th>" + Layout.LINE_SEP);
    sbuf.append("<th>Level</th>" + Layout.LINE_SEP);
    sbuf.append("<th>Category</th>" + Layout.LINE_SEP);
    if(locationInfo) {
      sbuf.append("<th>File:Line</th>" + Layout.LINE_SEP);
    }
    sbuf.append("<th>Message</th>" + Layout.LINE_SEP);
    sbuf.append("</tr>" + Layout.LINE_SEP);
    return sbuf.toString();
  }

  /**
     Returns the appropriate HTML footers.
  */
  public
  String getFooter() {
    StringBuffer sbuf = new StringBuffer();
    sbuf.append("</table>" + Layout.LINE_SEP);
    sbuf.append("<br>" + Layout.LINE_SEP);
    sbuf.append("</body></html>");
    return sbuf.toString();
  }
 
  /**
     The HTML layout handles the throwable contained in logging
     events. Hence, this method return <code>false</code>.  */
  public
  boolean ignoresThrowable() {
    return false;
  }

  /**
   * This method takes a string which may contain HTML tags (ie, <b>, <table>,
   * etc) and converts the '<' and '>' characters to their HTML escape
   * sequences.
   *
   * @param input The text to be converted.
   * @return The input string with the characters '<' and '>' replaced with
   *  &lt; and &gt; respectively.
   */
  private String escapeHTMLTags(String input) {
    //Check if the string is null or zero length -- if so, return
    //what was sent in.
    
    if( input == null || input.length() == 0 ) {
      return input;
    }
    
    //Use a StringBuffer in lieu of String concatenation -- it is
    //much more efficient this way.
    
    StringBuffer buf = new StringBuffer(input.length() + 6);
    char ch = ' ';
    
    int len = input.length();
    for(int i=0; i < len; i++) {
      ch = input.charAt(i);
      if(ch == '<') {
	buf.append("&lt;");
      } else if(ch == '>') {
	buf.append("&gt;");
      } else {
	buf.append(ch);
      }
    }

    return buf.toString();
  }
}