LOG4J使用技巧

# log4j1

maven依赖

<dependency>
     <groupId>log4j</groupId>
     <artifactId>log4j</artifactId>
     <version>1.2.16</version>
</dependency>

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使用样例

import org.apache.log4j.Logger;

public class Log4j1Demo {
    private static Logger logger = Logger.getLogger(Log4j1Demo.class);
    public static void main(String[] args) {
        logger.debug("=================");
        logger.info("=================");
        logger.warn("=================");
        logger.error("=================");
    }
}

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# log4j1+slf4j

maven依赖

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.16</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>1.6.6</version>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>1.6.6</version>
        </dependency>

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样例代码

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Log4j1Slf4jDemo {
    private static Logger logger = LoggerFactory.getLogger(Log4j1Slf4jDemo.class);
    public static void main(String[] args) {
        logger.debug("=================");
        logger.info("=================");
        logger.warn("=================");
        logger.error("=================");
    }
}

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# log4j2

使用Log4j2时需要将log4j1的jar包依赖去掉

maven依赖

  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.11.2</version>
  </dependency>
  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.11.2</version>
  </dependency>
  <dependency>
     <groupId>com.lmax</groupId>
     <artifactId>disruptor</artifactId>
     <version>3.3.4</version>
  </dependency>

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样例代码

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class Log4j2Demo {
    private static Logger logger = LogManager.getLogger(Log4j2Demo.class);
    public static void main(String[] args) {
        logger.debug("=================");
        logger.info("=================");
        logger.warn("=================");
        logger.error("=================");
    }
}

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# log4j2+slf4j

maven依赖

 <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version>2.11.2</version>
  </dependency>
  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.11.2</version>
  </dependency>
  <dependency>
     <groupId>com.lmax</groupId>
     <artifactId>disruptor</artifactId>
     <version>3.3.4</version>
  </dependency>  
  <dependency>
     <groupId>org.apache.logging.log4j</groupId>
     <artifactId>log4j-slf4j-impl</artifactId>
     <version>2.11.2</version>
  </dependency>

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样例代码和 log4j1+slf4j 的代码基本一致

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class Log4j2Slf4jDemo {
    private static Logger logger = LoggerFactory.getLogger(Log4j2Slf4jDemo.class);
    public static void main(String[] args) {
        logger.debug("=================");
        logger.info("=================");
        logger.warn("=================");
        logger.error("=================");
    }
}

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# log4j2和log4j1桥接

适用于原来项目中使用了 log4j1 的api升级log4j2的场景

maven 依赖,将log4j1的依赖删除,增加log4j2的依赖包以及以下的桥接包

  <dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-1.2-api</artifactId>
    <version>2.11.2</version>
  </dependency>

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样例代码

import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;

public class Log4j12Demo {
    private static Logger logger = Logger.getLogger(Log4j12Demo.class);
    private static org.apache.logging.log4j.Logger logger2= org.apache.logging.log4j.LogManager.getLogger(Log4j12Demo.class);
    public static void main(String[] args) {
        logger.debug("=================");
        logger.info("=================");
        logger.warn("=================");
        logger.error("=================");
        logger2.debug("=================");
        logger2.info("=================");
        logger2.warn("=================");
        logger2.error("=================");
    }
}

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编辑

上次更新: 2021/10/03, 23:00:07

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