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* SciJava Common shared library for SciJava software.

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* this list of conditions and the following disclaimer.

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package org.scijava.log;

import java.io.PrintWriter;

import java.io.StringWriter;

import java.util.Collection;

import java.util.Collections;

import java.util.Date;

import java.util.LinkedList;

import org.scijava.event.EventService;

/**

* A log message broadcast by a {@link Logger}.

* <p>

* NB: The message is published <em>on the calling thread</em> by

* {@link Logger#notifyListeners}, <em>not</em> on a dedicated event dispatch

* thread by the {@link EventService}. This is done to avoid the overhead of the

* event service's synchronized pub/sub implementation, as well as to avoid

* potential infinite loops caused by debugging log messages surrounding event

* publication.

* </p>

*

* @author Matthias Arzt

*/

public class LogMessage {

private final LogSource source;

private final int level;

private final String message;

private final Throwable throwable;

private final Date time;

private Collection<Object> attachments;

public LogMessage(LogSource source, int level, Object message,

Throwable throwable)

{

this.source = source;

this.attachments = null;

this.level = level;

this.message = message == null ? null : message.toString();

this.throwable = throwable;

this.time = new Date();

}

public LogMessage(LogSource source, int level, Object msg) {

this(source, level, msg, null);

}

/** Represents the source of the message. */

public LogSource source() {

return source;

}

/**

* Log level of the message.

*

* @see LogLevel

*/

public int level() {

return level;

}

/** The content of this log message. */

public String text() {

return message;

}

/** Exception associated with the log message. */

public Throwable throwable() {

return throwable;

}

/** Time of the creation of the log message. */

public Date time() {

return time;

}

/**

* Collection of objects that have been attached to this message with

* {@link #attach(Object)}.

*/

public Collection<Object> attachments() {

if (attachments == null) return Collections.emptyList();

return Collections.unmodifiableCollection(attachments);

}

/**

* Attach object to this log message. This can be used to attach additional

* information to the log message.

*/

public void attach(Object value) {

if (attachments == null) attachments = new LinkedList<>();

attachments.add(value);

}

// -- Object methods --

@Override

public String toString() {

final StringWriter sw = new StringWriter();

final PrintWriter printer = new PrintWriter(sw);

printer.print("[" + LogLevel.prefix(level()) + "] ");

if(text() != null) printer.println(text());

if (throwable() != null) {

throwable().printStackTrace(printer);

}

return sw.toString();

}

}