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// Jericho HTML Parser - Java based library for analysing and manipulating HTML
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// Version 3.2
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// Copyright (C) 2004-2009 Martin Jericho
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// http://jericho.htmlparser.net/
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of either one of the following licences:
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//
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// 1. The Eclipse Public License (EPL) version 1.0,
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// included in this distribution in the file licence-epl-1.0.html
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// or available at http://www.eclipse.org/legal/epl-v10.html
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//
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// 2. The GNU Lesser General Public License (LGPL) version 2.1 or later,
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// included in this distribution in the file licence-lgpl-2.1.txt
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// or available at http://www.gnu.org/licenses/lgpl.txt
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//
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// This library is distributed on an "AS IS" basis,
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// WITHOUT WARRANTY OF ANY KIND, either express or implied.
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// See the individual licence texts for more details.
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package net.htmlparser.jericho;
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/**
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* Defines the interface for handling log messages.
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* <p>
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* It is not usually necessary for users to create implementations of this interface, as
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* the {@link LoggerProvider} interface contains several predefined instances which provide the most commonly required <code>Logger</code> implementations.
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* <p>
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* By default, logging is configured automatically according to the algorithm described in the static {@link Config#LoggerProvider} property.
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* <p>
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* An instance of a class that implements this interface is used by calling the {@link Source#setLogger(Logger)} method on the relevant {@link Source} object.
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* <p>
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* Four <i><a name="LoggingLevel">logging levels</a></i> are defined in this interface.
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* The logging level is specified only by the use of different method names, there is no class or type defining the levels.
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* This makes the code required to wrap other logging frameworks much simpler and more efficient.
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* <p>
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* The four logging levels are:
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* <ul class="SmallVerticalMargin">
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* <li>{@link #error(String) ERROR}
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* <li>{@link #warn(String) WARN}
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* <li>{@link #info(String) INFO}
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* <li>{@link #debug(String) DEBUG}
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* </ul>
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* <p>
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* IMPLEMENTATION NOTE: Ideally the <code>java.util.logging.Logger</code> class could have been used as a basis for logging, even if used to define a wrapper
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* around other logging frameworks.
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* This would have avoided the need to define yet another logging interface, but because <code>java.util.logging.Logger</code> is implemented very poorly,
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* it is quite tricky to extend it as a wrapper.
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* Other logging wrapper frameworks such as <a target="_blank" href="http://www.slf4j.org/">SLF4J</a> or
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* <a target="_blank" href="http://jakarta.apache.org/commons/logging/">Jakarta Commons Logging</a> provide good logging interfaces, but to avoid
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* introducing dependencies it was decided to create this new interface.
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*
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* @see Config#LoggerProvider
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*/
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public interface Logger {
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/**
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* Logs a message at the ERROR level.
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* @param message the message to log.
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*/
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void error(String message);
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/**
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* Logs a message at the WARN level.
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* @param message the message to log.
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*/
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void warn(String message);
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/**
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* Logs a message at the INFO level.
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* @param message the message to log.
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*/
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void info(String message);
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/**
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* Logs a message at the DEBUG level.
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* @param message the message to log.
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*/
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void debug(String message);
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/**
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* Indicates whether logging is enabled at the ERROR level.
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* @return <code>true</code> if logging is enabled at the ERROR level, otherwise <code>false</code>.
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*/
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boolean isErrorEnabled();
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/**
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* Indicates whether logging is enabled at the WARN level.
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* @return <code>true</code> if logging is enabled at the WARN level, otherwise <code>false</code>.
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*/
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boolean isWarnEnabled();
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/**
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* Indicates whether logging is enabled at the INFO level.
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* @return <code>true</code> if logging is enabled at the INFO level, otherwise <code>false</code>.
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*/
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boolean isInfoEnabled();
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/**
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* Indicates whether logging is enabled at the DEBUG level.
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* @return <code>true</code> if logging is enabled at the DEBUG level, otherwise <code>false</code>.
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*/
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boolean isDebugEnabled();
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}
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