Introduction to three common ways to define Logger in Java

Logging is an indispensable part of Java development. It helps us track the running status of our programs, debug problems, and record important information. Java provides a variety of logging tools, among which Logger is one of the most commonly used loggers. This article will introduce in detail three ways to define Logger in Java to help you better understand and use the logging function.

1. Use

It is a logger built into Java, which provides basic logging functions. Logger makes it easy to log information without introducing third-party libraries.

1. Get a Logger instance

You can obtain a Logger instance through the () method.

import ;

public class LoggerExample {
    private static final Logger logger = (());

    public static void main(String[] args) {
        ("This is an info message.");
        ("This is a warning message.");
        ("This is a severe message.");
    }
}

2. Configure Logger

Logger can be configured via file or code.

Configuration file method

Configure log levels and processor in the file:

=INFO
=INFO
=

Code method

import ;
import ;

public class LoggerConfigExample {
    private static final Logger logger = (());

    public static void main(String[] args) {
        (); // Set log level        ("This is a fine message.");
    }
}

2. Use Log4j2 to define Logger

Log4j2 is a high-performance, flexible logging framework provided by Apache, which is widely used in various Java applications.

1. Introduce dependencies

Add Log4j2 dependency in

<dependency>
    <groupId>.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.17.1</version>
</dependency>

2. Configure Log4j2

Create a configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>
    </Appenders>
    <Loggers>
        <Root level="info">
            <AppenderRef ref="Console"/>
        </Root>
    </Loggers>
</Configuration>

3. Use Logger

import .;
import .;

public class Log4j2Example {
    private static final Logger logger = ();

    public static void main(String[] args) {
        ("This is an info message.");
        ("This is a warning message.");
        ("This is an error message.");
    }
}

3. Use SLF4J to define Logger

SLF4J (Simple Logging Facade for Java) is a logging facade that can be integrated with a variety of log frameworks (such as Log4j2, etc.).

1. Introduce dependencies

Add SLF4J and Log4j2 dependencies in :

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>1.7.36</version>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-log4j2</artifactId>
    <version>1.7.36</version>
</dependency>

2. Use Logger

import org.;
import org.;

public class SLF4JExample {
    private static final Logger logger = ();

    public static void main(String[] args) {
        ("This is an info message.");
        ("This is a warning message.");
        ("This is an error message.");
    }
}

4. Summary

This article introduces three ways to define Logger in Java: using , using Log4j2 and using SLF4J. Each method has its own characteristics and applicable scenarios.

It is a logger built into Java, suitable for simple logging needs; Log4j2 is a powerful logging framework suitable for scenarios that require high performance and flexible configuration; SLF4J is a logging facade that can be integrated with a variety of logging frameworks and provides a unified logging interface. Choosing the appropriate logging method according to project needs can improve the maintainability and scalability of the code.

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