EventLog.java #2

package com.perforce.api;

import java.io.*;
import java.util.*;
import java.net.*;
import java.text.*;

/*
 * Copyright (c) 2001, Perforce Software, All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * This class controls an event log. A set number of log entries are kept in
 * memory, but all log entries are sent to a log file.
 *
 * @author <a href="mailto:david@markley.cc">David Markley</a>
 * @version $Date: 2003/12/02 $ $Revision: #2 $
 */
public class EventLog {
  private static EventLog primary = null;
  private String title = "EventLog";
  private String filename = "log.txt";
  private PrintWriter fout = null;
  private Vector events;
  private int max_events = 100;
  private DateFormat fmt;

  /**
   * Default, no-argument constructor. This initialized the Vector of
   * events and the date and time format.
   *
   * @see Vector
   */
  public EventLog() {
    this(null, null);
  }

  /**
   * Constructor that accepts the title for this. The title is used when
   * the webSend() method is invoked.
   *
   * @param title  The title for this log.
   */
  public EventLog(String title) {
    this(title, null);
  }

  /** Constructor that sets the log title and ouput filename.
   *
   * @param title  The title for this log.
   * @param filename Name for the output file.
   */
  public EventLog(String title, String filename) {
    super();

    this.title = (null == title) ? "EventLog" : title;
    this.filename = (null == filename) ? "log.txt" : filename;
    events = new Vector();
    fmt = DateFormat.getDateTimeInstance(DateFormat.SHORT,DateFormat.MEDIUM);
    if (null == primary) {
      primary = this;
    }
    try {
      fout = new PrintWriter(new FileOutputStream(filename, true));
    } catch (Exception ex) {
      fout = null;
    }
  }

  /**
   * Returns the output file name.
   */
  public String getFileName() {
    return filename;
  }
  
  /**
   * Set the writer to send events to.
   */
  public void setWriter(Writer wr) {
    fout = new PrintWriter(wr);
  }
  
  /**
   * Set the writer to send events to.
   */
  public void setOutputStream(OutputStream out) {
    fout = new PrintWriter(out);
  }
  
  /**
   * Returns the size of the event log memory. This is the maximum number of
   * lines that will be maintained in memory.
   */
  public int getSize() {
    return max_events;
  }

  /**
   * Sets the size of the log. This is the maximum number of lines that the
   * log will maintain in memory.
   *
   * @param size  The number of lines to keep in the log.
   */
  public synchronized void setSize(int size) {
    max_events = size;
  }

  /**
   * Logs an event to the common log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   * @param level  Level for the logged event.
   * @param encode Indicates that the output should be XML/HTML encoded.
   */
  public static void commonLog(String event, String level, boolean encode) {
    if (null != primary) {
      primary.log(event, level, encode);
    } else {
      System.out.println(event);
    }
  }

  /**
   * Logs an event to the common log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   * @param level  Level for the logged event.
   */
  public static void commonLog(String event, String level) {
    if (null != primary) {
      primary.log(event, level);
    } else {
      System.out.println(event);
    }
  }

  /**
   * Logs an event to the common log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   */
  public static void commonLog(String event) {
    if (null != primary) {
      primary.log(event);
    } else {
      System.out.println(event);
    }
  }

  /**
   * Logs an event to this log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   */
  public synchronized void log(String event) {
    log(event,null,true);
  }

  /**
   * Logs an event to this log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   * @param level  Level for the logged event.
   */
  public synchronized void log(String event, String level) {
    log(event,level,true);
  }

  /**
   * Logs an event to this log. The event passed in is added to the 
   * log. If the log is beyond its maximum size, then the oldest events
   * are dropped.
   *
   * @param event  The event to be logged.
   * @param level  Level for the logged event.
   * @param encode Indicates that the output should be XML/HTML encoded.
   */
  public synchronized void log(String event, String level, boolean encode) {
    StringBuffer sb = new StringBuffer("<log level=\"");
    if (null == level) {
      if (-1 == event.indexOf("ERROR")) {
	sb.append("NOMINAL");
      } else {
	sb.append("ERROR");
      }
    } else {
      sb.append(level);
    }
    sb.append("\" date=\"");
    sb.append(fmt.format(new Date()));
    sb.append("\">");
    if (encode) {
      sb.append(Utils.HTMLEncode(event));
    } else {
      sb.append(event);
    }
    sb.append("</log>");
    String msg = sb.toString();
    events.insertElementAt(msg,0);
    if (null != fout) {
      fout.println(msg);
      fout.flush();
    }
    if (max_events < events.size()) {
      events.removeElementAt(max_events);
    }
  }

  /**
   * Returns an Enumeration that contains all the events in the log.
   *
   * @return  List of Strings in the log.
   */
  public synchronized Enumeration getLog() {
    return events.elements();
  }

  /**
   * Prints this log, using the specified format. Each line is placed in
   * the format string where {0} occurs.
   *
   * @param out  Print output.
   * @param format  Format to use.
   * @see java.text.MessageFormat
   */
  public static void printLog(PrintWriter out, String format) {
    printLog(primary, out, format);
  }

  /**
   * Prints a log, using the specified format. Each line is placed in
   * the format string where {0} occurs.
   *
   * @param elog  <code>EventLog</code> to print.
   * @param out  Print output.
   * @param format  Format to use.
   * @see java.text.MessageFormat
   */
  public static void printLog(EventLog elog, PrintWriter out, String format) {
    Object[] args = { "foo" };
    synchronized (elog) {
      Enumeration en = elog.events.elements();
      while (en.hasMoreElements()) {
	args[0] = ((String)en.nextElement());
	out.println(MessageFormat.format(format, args));
      }
    }
  }

  /**
   * Sets the title for this log.
   *
   * @param title  The title of the log.
   */
  public synchronized void setTitle(String title) {
    this.title = title;
  }

  /**
   * Gets the title of the log.
   */
  public synchronized String getTitle() {
    return title;
  }
}