Author: ceki Date: Mon Feb 9 21:20:15 2009 New Revision: 2147 Added: logback/trunk/logback-examples/src/main/java/chapter11/ logback/trunk/logback-examples/src/main/java/chapter11/Log4jMain.java logback/trunk/logback-examples/src/main/java/chapter11/LogbackMain.java logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jAppender.java logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jLayout.java logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackAppender.java logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackLayout.java logback/trunk/logback-examples/src/main/java/chapter11/log4jTrivial.properties logback/trunk/logback-examples/src/main/java/chapter11/logback-trivial.xml logback/trunk/logback-site/src/site/pages/manual/migrationFromLog4j.html Modified: logback/trunk/logback-examples/pom.xml logback/trunk/logback-site/src/site/pages/manual/appenders.html logback/trunk/logback-site/src/site/pages/manual/index.html logback/trunk/logback-site/src/site/pages/manual/menu.js Log: Added a chapter in the documentation about migrating log4j layouts and log4j appenders to logback as requested in LBSITE-27 Modified: logback/trunk/logback-examples/pom.xml ============================================================================== --- logback/trunk/logback-examples/pom.xml (original) +++ logback/trunk/logback-examples/pom.xml Mon Feb 9 21:20:15 2009 @@ -1,105 +1,110 @@ <project xmlns="http://maven.apache.org/POM/4.0.0" - xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" - xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> + xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" + xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> - <parent> - <groupId>ch.qos.logback</groupId> - <artifactId>logback-parent</artifactId> - <version>0.9.15-SNAPSHOT</version> - </parent> - - <modelVersion>4.0.0</modelVersion> - - <groupId>ch.qos.logback</groupId> - <artifactId>logback-examples</artifactId> - <version>${parent.version}</version> - <packaging>jar</packaging> - <name>Logback Examples Module</name> - - <url>http://logback.qos.ch</url> - <description> - Logback: the generic, reliable, fast and flexible logging - library for Java. - </description> - <licenses> - <license> - <name>GNU Lesser General Public License</name> - <url>http://www.gnu.org/licenses/lgpl.html</url> - </license> - </licenses> - - <dependencies> - - <dependency> - <groupId>ch.qos.logback</groupId> - <artifactId>logback-core</artifactId> - </dependency> - - <dependency> - <groupId>ch.qos.logback</groupId> - <artifactId>logback-classic</artifactId> - </dependency> - - <dependency> - <groupId>ch.qos.logback</groupId> - <artifactId>logback-access</artifactId> - </dependency> - - <dependency> - <groupId>org.slf4j</groupId> - <artifactId>slf4j-ext</artifactId> + <parent> + <groupId>ch.qos.logback</groupId> + <artifactId>logback-parent</artifactId> + <version>0.9.15-SNAPSHOT</version> + </parent> + + <modelVersion>4.0.0</modelVersion> + + <groupId>ch.qos.logback</groupId> + <artifactId>logback-examples</artifactId> + <version>${parent.version}</version> + <packaging>jar</packaging> + <name>Logback Examples Module</name> + + <url>http://logback.qos.ch</url> + <description> + Logback: the generic, reliable, fast and flexible logging library for Java. + </description> + <licenses> + <license> + <name>GNU Lesser General Public License</name> + <url>http://www.gnu.org/licenses/lgpl.html</url> + </license> + </licenses> + + <dependencies> + + <dependency> + <groupId>ch.qos.logback</groupId> + <artifactId>logback-core</artifactId> + </dependency> + + <dependency> + <groupId>ch.qos.logback</groupId> + <artifactId>logback-classic</artifactId> + </dependency> + + <dependency> + <groupId>ch.qos.logback</groupId> + <artifactId>logback-access</artifactId> + </dependency> + + <dependency> + <groupId>org.slf4j</groupId> + <artifactId>slf4j-ext</artifactId> <version>${slf4j.version}</version> - </dependency> + </dependency> - <dependency> - <groupId>javax.servlet</groupId> - <artifactId>servlet-api</artifactId> - <scope>compile</scope> - <optional>true</optional> - </dependency> - - </dependencies> - - <build> - <resources> - <resource> - <directory>src/main/resources</directory> - <filtering>true</filtering> - </resource> - </resources> - <plugins> - <plugin> - <groupId>org.apache.maven.plugins</groupId> - <artifactId>maven-compiler-plugin</artifactId> - <configuration> - <source>1.5</source> - <target>1.5</target> - </configuration> - </plugin> - - <plugin> - <artifactId>maven-antrun-plugin</artifactId> - <executions> - <execution> - <phase>package</phase> - <configuration> - <tasks> - <property name="slf4jJAR" - value="${settings.localRepository}/org/slf4j/slf4j-api/${slf4j.version}/slf4j-api-${slf4j.version}.jar" /> - <echo>Copying ${slf4jJAR} to lib/</echo> - <delete> - <fileset dir="lib/" - includes="slf4j-*SNAPSHOT.jar" /> - </delete> - <copy file="${slf4jJAR}" todir="lib/" /> - </tasks> - </configuration> - <goals> - <goal>run</goal> - </goals> - </execution> - </executions> - </plugin> - </plugins> - </build> + <dependency> + <groupId>log4j</groupId> + <artifactId>log4j</artifactId> + <version>1.2.14</version> + </dependency> + + + <dependency> + <groupId>javax.servlet</groupId> + <artifactId>servlet-api</artifactId> + <scope>compile</scope> + <optional>true</optional> + </dependency> + + </dependencies> + + <build> + <resources> + <resource> + <directory>src/main/resources</directory> + <filtering>true</filtering> + </resource> + </resources> + <plugins> + <plugin> + <groupId>org.apache.maven.plugins</groupId> + <artifactId>maven-compiler-plugin</artifactId> + <configuration> + <source>1.5</source> + <target>1.5</target> + </configuration> + </plugin> + + <plugin> + <artifactId>maven-antrun-plugin</artifactId> + <executions> + <execution> + <phase>package</phase> + <configuration> + <tasks> + <property name="slf4jJAR" + value="${settings.localRepository}/org/slf4j/slf4j-api/${slf4j.version}/slf4j-api-${slf4j.version}.jar" /> + <echo>Copying ${slf4jJAR} to lib/</echo> + <delete> + <fileset dir="lib/" includes="slf4j-*SNAPSHOT.jar" /> + </delete> + <copy file="${slf4jJAR}" todir="lib/" /> + </tasks> + </configuration> + <goals> + <goal>run</goal> + </goals> + </execution> + </executions> + </plugin> + </plugins> + </build> </project> \ No newline at end of file Added: logback/trunk/logback-examples/src/main/java/chapter11/Log4jMain.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/Log4jMain.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,30 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import org.apache.log4j.Logger; +import org.apache.log4j.PropertyConfigurator; + +/** + * A minimal application making use of log4j and TrivialLog4jAppender. + * + * @author Ceki Gülcü + * + */ +public class Log4jMain { + + static Logger logger = Logger.getLogger(Log4jMain.class); + + public static void main(String[] args) { + PropertyConfigurator.configure("src/main/java/chapter11/log4jTrivial.properties"); + logger.debug("Hello world"); + } + +} Added: logback/trunk/logback-examples/src/main/java/chapter11/LogbackMain.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/LogbackMain.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,44 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import ch.qos.logback.classic.LoggerContext; +import ch.qos.logback.classic.joran.JoranConfigurator; +import ch.qos.logback.core.joran.spi.JoranException; +import ch.qos.logback.core.util.StatusPrinter; + +/** + * A minimal application making use of logback-classic. It uses the + * configuration file logback-trivial.xml which makes use of + * TivialLogbackAppender. + * + * @author Ceki Gülcü + */ +public class LogbackMain { + + static Logger logger = LoggerFactory.getLogger(LogbackMain.class); + + public static void main(String[] args) throws JoranException { + LoggerContext lc = (LoggerContext) LoggerFactory.getILoggerFactory(); + + JoranConfigurator configurator = new JoranConfigurator(); + configurator.setContext(lc); + lc.reset(); + configurator.doConfigure("src/main/java/chapter11/logback-trivial.xml"); + StatusPrinter.printInCaseOfErrorsOrWarnings(lc); + + + logger.debug("Hello world"); + } + +} Added: logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jAppender.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jAppender.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,30 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import org.apache.log4j.AppenderSkeleton; +import org.apache.log4j.spi.LoggingEvent; + +public class TrivialLog4jAppender extends AppenderSkeleton { + + protected void append(LoggingEvent loggingevent) { + String s = this.layout.format(loggingevent); + System.out.println(s); + } + + public void close() { + // nothing to do + } + + public boolean requiresLayout() { + return true; + } + +} Added: logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jLayout.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/TrivialLog4jLayout.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,39 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import org.apache.log4j.Layout; +import org.apache.log4j.spi.LoggingEvent; + + +/** + * + * A very simple log4j layout which formats a logging event + * by returning the message contained therein. + * + * @author Ceki Gülcü + * + */ +public class TrivialLog4jLayout extends Layout { + + public void activateOptions() { + // there are no options to activate + } + + public String format(LoggingEvent loggingEvent) { + return loggingEvent.getRenderedMessage(); + } + + @Override + public boolean ignoresThrowable() { + return true; + } + +} Added: logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackAppender.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackAppender.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,35 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import ch.qos.logback.classic.spi.LoggingEvent; +import ch.qos.logback.core.AppenderBase; + +public class TrivialLogbackAppender extends AppenderBase<LoggingEvent> { + + @Override + public void start() { + if (this.layout == null) { + addError("No layout set for the appender named [" + name + "]."); + return; + } + super.start(); + } + + @Override + protected void append(LoggingEvent loggingevent) { + // note that AppenderBase.doAppend will invoke this method only if + // this appender was successfully started. + + String s = this.layout.doLayout(loggingevent); + System.out.println(s); + } + +} Added: logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackLayout.java ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/TrivialLogbackLayout.java Mon Feb 9 21:20:15 2009 @@ -0,0 +1,29 @@ +/** + * Logback: the generic, reliable, fast and flexible logging framework. + * + * Copyright (C) 2000-2009, QOS.ch + * + * 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. + */ +package chapter11; + +import ch.qos.logback.classic.spi.LoggingEvent; +import ch.qos.logback.core.LayoutBase; + + +/** + * + * A very simple logback-classic layout which formats a logging event + * by returning the message contained therein. + * + * @author Ceki Gülcü + * + */ +public class TrivialLogbackLayout extends LayoutBase<LoggingEvent> { + + public String doLayout(LoggingEvent loggingEvent) { + return loggingEvent.getMessage(); + } +} Added: logback/trunk/logback-examples/src/main/java/chapter11/log4jTrivial.properties ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/log4jTrivial.properties Mon Feb 9 21:20:15 2009 @@ -0,0 +1,3 @@ +log4j.rootLogger=DEBUG, TRIVIAL +log4j.appender.TRIVIAL=chapter11.TrivialLog4jAppender +log4j.appender.TRIVIAL.layout=chapter11.TrivialLog4jLayout \ No newline at end of file Added: logback/trunk/logback-examples/src/main/java/chapter11/logback-trivial.xml ============================================================================== --- (empty file) +++ logback/trunk/logback-examples/src/main/java/chapter11/logback-trivial.xml Mon Feb 9 21:20:15 2009 @@ -0,0 +1,10 @@ +<?xml version="1.0" encoding="UTF-8"?> + +<configuration> + <appender name="TRIVIAL" class="chapter11.TrivialLogbackAppender"> + <layout class="chapter11.TrivialLogbackLayout"/> + </appender> + <root level="DEBUG"> + <appender-ref ref="TRIVIAL"/> + </root> +</configuration> \ No newline at end of file Modified: logback/trunk/logback-site/src/site/pages/manual/appenders.html ============================================================================== --- logback/trunk/logback-site/src/site/pages/manual/appenders.html (original) +++ logback/trunk/logback-site/src/site/pages/manual/appenders.html Mon Feb 9 21:20:15 2009 @@ -3238,8 +3238,6 @@ static int DEFAULT_LIMIT = 16; int counter = 0; int limit = DEFAULT_LIMIT; - - private Layout<LoggingEvent> layout; public CountingConsoleAppender() { } @@ -3275,38 +3273,37 @@ counter++; } - public Layout<LoggingEvent> getLayout() { - return layout; - } - - public void setLayout(Layout<LoggingEvent> layout) { - this.layout = layout; - } }</p> <p>The <code>start()</code> method checks for the presence of a - <code>Layout</code>. In case none is found, the appender is not - started. + <code>Layout</code>. In case the layout is not set, the appender + fails to start with an error message. </p> <p>This custom appender illustrates a two points: </p> <ul> - <li>All properties that follow the setter/getter JavaBeans - conventions are handled transparently. The <code>start()</code> - method, that is called automatically, has the responsability to - check that the given properties are coherent. + + <li>All properties that follow the setter/getter JavaBeans + conventions are handled transparently. The <code>start()</code> + method, which is called automatically during logback + configuration, has the responsibility to verify that the various + properties of the appender are coherent. </li> + <li>The <code>AppenderBase.doAppend()</code> method invokes the - append() method of its derived classes where actual output - operations occur. It is in this method that appenders format - events by invoking their layouts. + append() method of its derived classes. Actual output + operations occur in the <code>append</code>() method. In + particular, it is in this method that appenders format events by + invoking their layouts. </li> </ul> - <p>The <code>CountingConsoleAppender</code> can be configured like - any appender. See sample file + <p>The <a + href="../xref/chapter4/CountingConsoleAppender.html"><code>CountingConsoleAppender</code></a> + can be configured like any appender. See sample configuration + file <em>logback-examples/src/main/java/chapter4/countingConsole.xml</em> for an example. </p> Modified: logback/trunk/logback-site/src/site/pages/manual/index.html ============================================================================== --- logback/trunk/logback-site/src/site/pages/manual/index.html (original) +++ logback/trunk/logback-site/src/site/pages/manual/index.html Mon Feb 9 21:20:15 2009 @@ -24,11 +24,22 @@ <h2>The logback manual</h2> + <div class="highlight"> + <p> + If you wish to print chapters in this document, we recommend + that you do so using <a + href="http://www.getfirefox.com">Firefox 2</a>, with <em>Adapt to + page size</em> enabled, or <a + href="http://www.opera.com">Opera</a>. + </p> + </div> + <p>The complete logback manual documents the latest version of - logback framework. In over 140 pages and dozens of concrete + logback framework. In over 150 pages and dozens of concrete examples, it covers both basic and advanced logback features: </p> + <div> <ul> <li><p>the overall logback architecture</p></li> @@ -38,28 +49,11 @@ <li><p>layouts</p></li> <li><p>filters</p></li> <li><p>mapped diagnostic contexts</p></li> - <li><p>logback default initialization</p></li> - <li><p>logback in Servlet Containers</p></li> + <li><p>joran, logback's configuration system</p></li> </ul> </div> - - <div class="highlight"> - <p> - If you wish to print chapters in this document, we recommend - that you do so using <a - href="http://www.getfirefox.com">Firefox 2</a>, with <em>Adapt to - page size</em> enabled, or <a - href="http://www.opera.com">Opera</a>. - </p> - <p> - To run the examples provided in this book, you might have - to run the provided script to setup your classpath. The scripts - can be found in the logback distributions, inside the <em>logback-examples</em> - directory. - </p> - </div> - + <p>The logback manual describes the logback API in considerable detail, including its features and design rationale. Authored by Ceki Gülcü and Sébastien Pennec, the main @@ -69,6 +63,8 @@ the aid of introductory material and many examples, new users should quickly come up to speed. </p> + + <div> <p>Without further ado, here are the contents of the manual:</p> @@ -112,6 +108,10 @@ <a href="onJoran.html"><b>Chapter 10: Joran</b></a> </p></li> + <li><p> + <a href="migrationFromLog4j.html"><b>Chapter 11: Migration from log4j</b></a> + </p></li> + </ul> </div> Modified: logback/trunk/logback-site/src/site/pages/manual/menu.js ============================================================================== --- logback/trunk/logback-site/src/site/pages/manual/menu.js (original) +++ logback/trunk/logback-site/src/site/pages/manual/menu.js Mon Feb 9 21:20:15 2009 @@ -10,3 +10,4 @@ document.write('<p class="menu"><a href="loggingSeparation.html"><b>Ch8: Logging Separation</b></a>'); document.write('<p class="menu"><a href="jmxConfig.html"><b>Ch9: JMX Configurator</b></a>'); document.write('<p class="menu"><a href="onJoran.html"><b>Ch10: Joran</b></a>'); +document.write('<p class="menu"><a href="migrationFromLog4j.html"><b>Ch11: Migration from log4j</b></a>'); Added: logback/trunk/logback-site/src/site/pages/manual/migrationFromLog4j.html ============================================================================== --- (empty file) +++ logback/trunk/logback-site/src/site/pages/manual/migrationFromLog4j.html Mon Feb 9 21:20:15 2009 @@ -0,0 +1,203 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" + "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> + +<html xmlns="http://www.w3.org/1999/xhtml"> + <head> + <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" /> + <title>Migration from log4j</title> + <link rel="stylesheet" type="text/css" href="../css/common.css" /> + <link rel="stylesheet" type="text/css" href="../css/screen.css" media="screen" /> + <link rel="stylesheet" type="text/css" href="../css/_print.css" media="print" /> + + </head> + <body> + <script type="text/javascript">prefix='../'</script> + <script src="../templates/header.js" type="text/javascript"></script> + <div id="left"> + <script src="../templates/left.js" type="text/javascript"></script> + </div> + <div id="right"> + <script src="menu.js" type="text/javascript"></script> + </div> + <div id="content"> + + <h2>Migration from log4j</h2> + + + <p>This chapter deals with the topic of migrating custom log4j + components such as appenders or layouts to logback-classic. + </p> + + <p>Software which merely invokes log4j client API, that is the + <code>Logger</code> or <code>Category</code> classes in + <code>org.apache.log4j</code> package, can be automatically + migrated to use SLF4J via the <a + href="http://www.slf4j.org/migrator.html">SLF4J migrator + tool</a>. + </p> + + <p>From a broader perspective, log4j and logback-classic are + closely related. The core components, such as loggers, appenders + and layouts exist in both frameworks and serve identical + purposes. Similarly, the most important internal data-structure, + namely <code>LoggingEvent</code> exists in both frameworks with + rather similar but non-identical implementations. Most of the + changes requried in migrating log4j components to logback-classic + are related to differences in implementation of the + <code>LoggingEvent</code> class. Rest assured, these differences + are rather limited. If in spite of your best efforts you are + unable to migrate any given log4j component to logback-classic, do + post a question on the <a href="../mailinglist.html">logback-dev + mailing list</a>. A logback developper should be able to provide + guidance. + </p> + + + <h3>Migrating a log4j layout</h3> + + <p>Let us begin by migrating a hypothetcical and trivially simple + log4j layout named <a + href="../xref/chapter11/TrivialLog4jLayout.html">TrivialLog4jLayout</a> + which returns the message contained in a logging events as the + formatted message. Here is the code. + </p> + + + <p class="source">package chapter11; + +import org.apache.log4j.Layout; +import org.apache.log4j.spi.LoggingEvent; + +public class TrivialLog4jLayout extends Layout { + + public void activateOptions() { + // there are no options to activate + } + + public String format(LoggingEvent loggingEvent) { + return loggingEvent.getRenderedMessage(); + } + + public boolean ignoresThrowable() { + return true; + } +}</p> + + <p>The logback-classic equivalent named <a + href="../xref/chapter11/TrivialLogbackLayout.html">TrivialLogbackLayout</a> + would be </p> + + <p class="source">package chapter11; + +import ch.qos.logback.classic.spi.LoggingEvent; +import ch.qos.logback.core.LayoutBase; + +public class TrivialLogbackLayout extends <b>LayoutBase<LoggingEvent></b> { + + public String <b>doLayout</b>(LoggingEvent loggingEvent) { + return loggingEvent.getMessage(); + } +} </p> + + <p>As you can see, in a logback-classic layout, the formatting + method is named <code>doLayout</code> instead of + <code>format</code>() in log4j. The <code>ignoresThrowable</code>() + method is not needed and has no equivalent in logback-classic. Note + that a logback-classic layout must extend the + <code>LayoutBase<LoggingEvent></code> class. + </p> + + <p>The <code>activateOptions</code>() method merits further + discussion. In log4j, a layout will have its + <code>activateOptions</code>() method invoked by log4j + configurators, that is <code>PropertyConfigurator</code> or + <code>DOMConfigurator</code> just after all the options of the + layout have been set. Thus, the layout will have an oppurtunity to + check that its options are coherent and if so, proceed to fully + intialize itself.</p> + + + <p>In logback-classic, layouts must implement the <a + href="../xref/ch/qos/logback/core/spi/LifeCycle.html">LifeCycle</a> + interface which includes a method called <code>start</code>(). The + <code>start</code>() method is the equivalent of log4j's + <code>activateOptions</code>() method. + </p> + + <h3>Migrating a log4j appender</h3> + + <p>Migrating an appender is quite similar to migrating layout. Here + is a trivially simple appender called <a + href="../xref/chapter11/TrivialLog4jLayout.html">TrivialLog4jLayout</a> + which writes on the console the string returned by its layout.</p> + + <p class="source">package chapter11; + +import org.apache.log4j.AppenderSkeleton; +import org.apache.log4j.spi.LoggingEvent; + + +public class TrivialLog4jAppender extends AppenderSkeleton { + + protected void append(LoggingEvent loggingevent) { + String s = this.layout.format(loggingevent); + System.out.println(s); + } + + public void close() { + // nothing to do + } + + public boolean requiresLayout() { + return true; + } +}</p> + + <p>The logback-classic equivalent named <a + href="../xref/chapter11/TrivialLogbackAppender.html">TrivialLogbackAppender</a> + would be written as</p> + + + <p class="source">package chapter11; + +import ch.qos.logback.classic.spi.LoggingEvent; +import ch.qos.logback.core.AppenderBase; + +public class TrivialLogbackAppender extends AppenderBase<LoggingEvent> { + + @Override + public void start() { + if (this.layout == null) { + addError("No layout set for the appender named [" + name + "]."); + return; + } + super.start(); + } + + @Override + protected void append(LoggingEvent loggingevent) { + // note that AppenderBase.doAppend will invoke this method only if + // this appender was successfully started. + + String s = this.layout.doLayout(loggingevent); + System.out.println(s); + } +}</p> + + + <p>Comparing the two classes, you should notice that the contents + of the <code>append</code>() method remains unchanged. The + <code>requiresLayout</code> method is not used in logback and can + be removed. In logback, the <code>stop</code>() method is the + equivalent of log4j's <code>close</code>() method. However, + <code>AppenderBase</code> in logback-classic, contains an nop + implementation for <code>stop</code> which is sufficient for the + purposes of this trivial appender. + </p> + + + + <script src="../templates/footer.js" type="text/javascript"></script> +</div> +</body> +</html>