Logging

public class Program {
    private Logger logger = LoggerFactory.gerLogger(SomeClass.class);

    // ...
}

public class Program {
    private Logger logger = LoggerFactory.gerLogger(SomeClass.class);

    public static void main(String[] args) {
        logger.info("Application started");
        logger.debug("Or not");
    }

    // ...
}

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration debug="false" xmlns:log4j="http://jakarta.apache.org/log4j/">
    <appender name="ConsoleAppender" class="org.apache.log4j.ConsoleAppender">
        <param name="Encoding" value="Cp866"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{ISO8601} [%-5p][%-16.16t][%32.32c] - %m%n" />
        </layout>
    </appender>
    <root>
        <priority value="DEBUG"/>
        <appender-ref ref="ConsoleAppender" />
    </root>
</log4j:configuration>

log4j.debug = false
log4j.rootLogger = DEBUG, ConsoleAppender
# CONSOLE appender customisation
log4j.appender.ConsoleAppender = org.apache.log4j.ConsoleAppender
log4j.appender.ConsoleAppender.encoding = Cp866
log4j.appender.ConsoleAppender.layout = org.apache.log4j.PatternLayout
log4j.appender.ConsoleAppender.layout.ConversionPattern = %d{ISO8601} [%-5p][%-16.16t][%32.32c] - %m%n
# File appender customisation
log4j.appender.FILE=org.apache.log4j.RollingFileAppender
log4j.appender.FILE.File=./target/logging/logging.log
log4j.appender.FILE.MaxFileSize=1MB log4j.appender.FILE.threshold=DEBUG log4j.appender.FILE.MaxBackupIndex=2 log4j.appender.FILE.layout=org.apache.log4j.PatternLayout log4j.appender.FILE.layout.ConversionPattern=[ %-5p] - %c:%L - %m%n

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender

log4j.appender.FILE=org.apache.log4j.RollingFileAppender

log4j.rootLogger=DEBUG, CONSOLE, FILE

log4j.logger.com.github.romankh3.logginglecture=TRACE, OWN, CONSOLE

# CONSOLE appender customisation
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.threshold=DEBUG
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=[%-5p] : %c:%L : %m%n

# File appender customisation
log4j.appender.FILE=org.apache.log4j.RollingFileAppender
log4j.appender.FILE.File=./target/logging/logging.log
log4j.appender.FILE.MaxFileSize=1MB
log4j.appender.FILE.threshold=DEBUG
log4j.appender.FILE.MaxBackupIndex=2
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.ConversionPattern=[ %-5p] - %c:%L - %m%n

log4j.appender.FILE.File=./target/logging/logging.log

public class Program {
    private org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ClassName.class);
}

public class Program {
    private org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ClassName.class);

    public static void main(String[] args) {
        logger.trace("Method 1 started with argument={}", argument);
        logger.debug("Database updated with script = {}", script);
        logger.info("Application has started on port = {}", port);
        logger.warn("Log4j didn't find log4j.properties.Please, provide them");
        logger.error("Connection refused to host = {}", host);
    }
}

public class Program {
    private org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(ClassName.class);

    public static void main(String[] args) {
        logger.log(Level.INFO, argument);
    }
}

<dependencies>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>${log4j.version}</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>${log4j.version}</version>
    </dependency>
</dependencies>

import org.apache.logging.log4j.Logger;

public class Program {
    private Logger log = LogManager.getLogger(LoggingLog4j.class);

    // ...
}

public class Program {
    private Logger log = LogManager.getLogger(LoggingLog4j.class);

    public static void main(String[] args){
        // Карта сообщений (напечатается как msg1="Сообщение 1” msg2="Сообщение 2”)
        MapMessage mapMessage = new MapMessage();
        mapMessage.put("msg1", "Сообщение 1");
        mapMessage.put("msg2", "Сообщение 2");
        // Маркер, объект по которому можно фильтровать сообщения
        Marker marker = MarkerManager.getMarker("fileonly");
        // Строковое сообщение
        String stringMessage = "Сообщение";
        // Строковое сообщение с параметрами
        String stringMessageFormat = "Сообщение {}, от {}";
        // Исключение
        Throwable throwable = new Throwable();
        // Объект
        Object object = new Object();
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
    <!-- Секция appenders -->
    <Appenders>
        <!-- Файловый appender -->
        <File name="file" fileName="log.log">
            <PatternLayout>
                <Pattern>%d %p %c{1.} [%t] %m %ex%n</Pattern>
            </PatternLayout>
        </File>
        <!-- Файловый appender -->
        <File name="file2" fileName="log2.log">
            <!-- Фильтр по маркеру -->
            <MarkerFilter marker="fileonly" onMatch="DENY" onMismatch="ACCEPT"/>
            <PatternLayout>
                <Pattern>%d %p %c{1.} [%t] %m %ex%n</Pattern>
            </PatternLayout>
        </File>
    </Appenders>
    <!-- Секция loggers -->
    <Loggers>
        <!-- Корневой logger -->
        <Root level="trace">
            <AppenderRef ref="file" level="DEBUG"/>
        </Root>
        <!-- Logger нашего класса -->
        <Logger name="logging.log4j.LoggingLog4j" level="info" additivity="false">
            <AppenderRef ref="file2" level="INFO"/>
        </Logger>
    </Loggers>
</Configuration>

<dependency>
    <groupId>ch.qos.logback</groupId>
    <artifactId>logback-classic</artifactId>
    <version>1.2.6</version>
</dependency>

public class Program {
    private org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LoggingLogback.class);

    // ...
}

public class Program {
    private org.slf4j.Logger log = org.slf4j.LoggerFactory.getLogger(LoggingLogback.class);

    public static void main(String[] args) {
        // Строковое сообщение
        String stringMessage = "Сообщение";
        // Шаблон сообщения
        String stringMessageFormat = "Сообщение {} {}";
        // Ошибка
        Throwable throwable = new Throwable();
        // Маркер
        Marker marker = MarkerFactory.getMarker("marker");
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <!--Аппендеры -->
    <!--Файловый appender -->
    <appender name="file" class="ch.qos.logback.core.FileAppender">
        <file>log.log</file>
        <layout class="ch.qos.logback.classic.PatternLayout">
            <Pattern>%date %level [%thread] %logger{10} [%file:%line] %msg%n</Pattern>
        </layout>
    </appender>
    <!--Консольный appender -->
    <appender name="sout" class="ch.qos.logback.core.ConsoleAppender">
        <layout class="ch.qos.logback.classic.PatternLayout">
            <Pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n</Pattern>
        </layout>
    </appender>
    <!-- Фильтры -->
    <!-- Фильтр по маркеру -->
    <turboFilter class="ch.qos.logback.classic.turbo.MarkerFilter">
        <Marker>marker</Marker>
        <OnMatch>DENY</OnMatch>
    </turboFilter>
    <!-- Loggers -->
    <!-- Корневой logger -->
    <root level="info">
        <appender-ref ref="file" />
    </root>
    <!-- Logger нашего класса -->
    <logger name="logging.logback.LoggingLogback" level="info" >
        <appender-ref ref="sout" />
    </logger>
</configuration>

<dependencies>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
        <version>2.7</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
        <version>2.7</version>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
        <version>2.7</version>
    </dependency>
</dependencies>