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JCommon is a free general purpose Java class library that is used in
several projects at www.jfree.org, including JFreeChart and
JFreeReport.
/* ========================================================================
* JCommon : a free general purpose class library for the Java(tm) platform
* ========================================================================
*
* (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
*
* Project Info: http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* --------
* Log.java
* --------
* (C)opyright 2002-2004, by Thomas Morgner and Contributors.
*
* Original Author: Thomas Morgner ([email protected]);
* Contributor(s): David Gilbert (for Object Refinery Limited);
*
* $Id: Log.java,v 1.5 2006/06/08 17:42:20 taqua Exp $
*
* Changes
* -------
* 29-Apr-2003 : Distilled from the JFreeReport project and moved into JCommon
* 11-Jun-2003 : Removing LogTarget did not work.
*
*/
package org.jfree.util;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
/**
* A simple logging facility. Create a class implementing the {@link org.jfree.util.LogTarget}
* interface to use this feature.
*
* @author Thomas Morgner
*/
public class Log {
/**
* A simple message class.
*/
public static class SimpleMessage {
/**
* The message.
*/
private String message;
/**
* The parameters.
*/
private Object[] param;
/**
* Creates a new message.
*
* @param message the message text.
* @param param1 parameter 1.
*/
public SimpleMessage(final String message, final Object param1) {
this.message = message;
this.param = new Object[]{param1};
}
/**
* Creates a new message.
*
* @param message the message text.
* @param param1 parameter 1.
* @param param2 parameter 2.
*/
public SimpleMessage(final String message, final Object param1,
final Object param2) {
this.message = message;
this.param = new Object[]{param1, param2};
}
/**
* Creates a new message.
*
* @param message the message text.
* @param param1 parameter 1.
* @param param2 parameter 2.
* @param param3 parameter 3.
*/
public SimpleMessage(final String message, final Object param1,
final Object param2, final Object param3) {
this.message = message;
this.param = new Object[]{param1, param2, param3};
}
/**
* Creates a new message.
*
* @param message the message text.
* @param param1 parameter 1.
* @param param2 parameter 2.
* @param param3 parameter 3.
* @param param4 parameter 4.
*/
public SimpleMessage(final String message, final Object param1,
final Object param2, final Object param3,
final Object param4) {
this.message = message;
this.param = new Object[]{param1, param2, param3, param4};
}
/**
* Creates a new message.
*
* @param message the message text.
* @param param the parameters.
*/
public SimpleMessage(final String message, final Object[] param) {
this.message = message;
this.param = param;
}
/**
* Returns a string representation of the message (useful for debugging).
*
* @return the string.
*/
public String toString() {
final StringBuffer b = new StringBuffer();
b.append(this.message);
if (this.param != null) {
for (int i = 0; i < this.param.length; i++) {
b.append(this.param[i]);
}
}
return b.toString();
}
}
/**
* The logging threshold.
*/
private int debuglevel;
/**
* Storage for the log targets.
*/
private LogTarget[] logTargets;
/** The log contexts. */
private HashMap logContexts;
/**
* the singleton instance of the Log system.
*/
private static Log singleton;
/**
* Creates a new Log instance. The Log is used to manage the log targets.
*/
protected Log() {
this.logContexts = new HashMap();
this.logTargets = new LogTarget[0];
this.debuglevel = 100;
}
/**
* Returns the singleton Log instance. A new instance is created if necessary.
*
* @return the singleton instance.
*/
public static synchronized Log getInstance() {
if (singleton == null) {
singleton = new Log();
}
return singleton;
}
/**
* Redefines or clears the currently used log instance.
*
* @param log the new log instance or null, to return to the default implementation.
*/
protected static synchronized void defineLog(final Log log) {
singleton = log;
}
/**
* Returns the currently defined debug level. The higher the level, the more details
* are printed.
*
* @return the debug level.
*/
public int getDebuglevel() {
return this.debuglevel;
}
/**
* Defines the debug level for the log system.
*
* @param debuglevel the new debug level
* @see #getDebuglevel()
*/
protected void setDebuglevel(final int debuglevel) {
this.debuglevel = debuglevel;
}
/**
* Adds a log target to this facility. Log targets get informed, via the LogTarget interface,
* whenever a message is logged with this class.
*
* @param target the target.
*/
public synchronized void addTarget(final LogTarget target) {
if (target == null) {
throw new NullPointerException();
}
final LogTarget[] data = new LogTarget[this.logTargets.length + 1];
System.arraycopy(this.logTargets, 0, data, 0, this.logTargets.length);
data[this.logTargets.length] = target;
this.logTargets = data;
}
/**
* Removes a log target from this facility.
*
* @param target the target to remove.
*/
public synchronized void removeTarget(final LogTarget target) {
if (target == null) {
throw new NullPointerException();
}
final ArrayList l = new ArrayList();
l.addAll(Arrays.asList(this.logTargets));
l.remove(target);
final LogTarget[] targets = new LogTarget[l.size()];
this.logTargets = (LogTarget[]) l.toArray(targets);
}
/**
* Returns the registered logtargets.
*
* @return the logtargets.
*/
public LogTarget[] getTargets() {
return (LogTarget[]) this.logTargets.clone();
}
/**
* Replaces all log targets by the given target.
*
* @param target the new and only logtarget.
*/
public synchronized void replaceTargets(final LogTarget target) {
if (target == null) {
throw new NullPointerException();
}
this.logTargets = new LogTarget[]{target};
}
/**
* A convenience method for logging a 'debug' message.
*
* @param message the message.
*/
public static void debug(final Object message) {
log(LogTarget.DEBUG, message);
}
/**
* A convenience method for logging a 'debug' message.
*
* @param message the message.
* @param e the exception.
*/
public static void debug(final Object message, final Exception e) {
log(LogTarget.DEBUG, message, e);
}
/**
* A convenience method for logging an 'info' message.
*
* @param message the message.
*/
public static void info(final Object message) {
log(LogTarget.INFO, message);
}
/**
* A convenience method for logging an 'info' message.
*
* @param message the message.
* @param e the exception.
*/
public static void info(final Object message, final Exception e) {
log(LogTarget.INFO, message, e);
}
/**
* A convenience method for logging a 'warning' message.
*
* @param message the message.
*/
public static void warn(final Object message) {
log(LogTarget.WARN, message);
}
/**
* A convenience method for logging a 'warning' message.
*
* @param message the message.
* @param e the exception.
*/
public static void warn(final Object message, final Exception e) {
log(LogTarget.WARN, message, e);
}
/**
* A convenience method for logging an 'error' message.
*
* @param message the message.
*/
public static void error(final Object message) {
log(LogTarget.ERROR, message);
}
/**
* A convenience method for logging an 'error' message.
*
* @param message the message.
* @param e the exception.
*/
public static void error(final Object message, final Exception e) {
log(LogTarget.ERROR, message, e);
}
/**
* Logs a message to the main log stream. All attached log targets will also
* receive this message. If the given log-level is higher than the given debug-level
* in the main config file, no logging will be done.
*
* @param level log level of the message.
* @param message text to be logged.
*/
protected void doLog(int level, final Object message) {
if (level > 3) {
level = 3;
}
if (level <= this.debuglevel) {
for (int i = 0; i < this.logTargets.length; i++) {
final LogTarget t = this.logTargets[i];
t.log(level, message);
}
}
}
/**
* Logs a message to the main log stream. All attached log targets will also
* receive this message. If the given log-level is higher than the given debug-level
* in the main config file, no logging will be done.
*
* @param level log level of the message.
* @param message text to be logged.
*/
public static void log(final int level, final Object message) {
getInstance().doLog(level, message);
}
/**
* Logs a message to the main log stream. All attached logTargets will also
* receive this message. If the given log-level is higher than the given debug-level
* in the main config file, no logging will be done.
*
* The exception's stacktrace will be appended to the log-stream
*
* @param level log level of the message.
* @param message text to be logged.
* @param e the exception, which should be logged.
*/
public static void log(final int level, final Object message, final Exception e) {
getInstance().doLog(level, message, e);
}
/**
* Logs a message to the main log stream. All attached logTargets will also
* receive this message. If the given log-level is higher than the given debug-level
* in the main config file, no logging will be done.
*
* The exception's stacktrace will be appended to the log-stream
*
* @param level log level of the message.
* @param message text to be logged.
* @param e the exception, which should be logged.
*/
protected void doLog(int level, final Object message, final Exception e) {
if (level > 3) {
level = 3;
}
if (level <= this.debuglevel) {
for (int i = 0; i < this.logTargets.length; i++) {
final LogTarget t = this.logTargets[i];
t.log(level, message, e);
}
}
}
/**
* Initializes the logging system. Implementors should
* override this method to supply their own log configuration.
*/
public void init() {
// this method is intentionally empty.
}
/**
* Returns true, if the log level allows debug messages to be
* printed.
*
* @return true, if messages with an log level of DEBUG are allowed.
*/
public static boolean isDebugEnabled() {
return getInstance().getDebuglevel() >= LogTarget.DEBUG;
}
/**
* Returns true, if the log level allows informational
* messages to be printed.
*
* @return true, if messages with an log level of INFO are allowed.
*/
public static boolean isInfoEnabled() {
return getInstance().getDebuglevel() >= LogTarget.INFO;
}
/**
* Returns true, if the log level allows warning messages to be
* printed.
*
* @return true, if messages with an log level of WARN are allowed.
*/
public static boolean isWarningEnabled() {
return getInstance().getDebuglevel() >= LogTarget.WARN;
}
/**
* Returns true, if the log level allows error messages to be
* printed.
*
* @return true, if messages with an log level of ERROR are allowed.
*/
public static boolean isErrorEnabled() {
return getInstance().getDebuglevel() >= LogTarget.ERROR;
}
/**
* Creates a log context.
*
* @param context the class (null not permitted).
*
* @return A log context.
*/
public static LogContext createContext(final Class context) {
return createContext(context.getName());
}
/**
* Creates a log context.
*
* @param context the label for the context.
*
* @return A log context.
*/
public static LogContext createContext(final String context) {
return getInstance().internalCreateContext(context);
}
/**
* Creates a log context.
*
* @param context the name of the logging context (a common prefix).
*
* @return A log context.
*/
protected LogContext internalCreateContext(final String context) {
synchronized (this) {
LogContext ctx = (LogContext) this.logContexts.get(context);
if (ctx == null) {
ctx = new LogContext(context);
this.logContexts.put(context, ctx);
}
return ctx;
}
}
}
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