Log4j2+Slf4j快速入门

前言

        本文目的在于让RD快速掌握Log4j2+Slf4j在Java Web项目中的使用。

        注意：该方法对Servlet3.0+适用，Servlet2.5以前的版本还需额外的步骤，详见：Servlet-2.5。

Maven依赖

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-api</artifactId>
    <version> 2.5 </version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version> 2.5 </version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-web</artifactId>
    <version> 2.5 </version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version> 1.7 . 13 </version>
</dependency>
<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-slf4j-impl</artifactId>
    <version> 2.5 </version>
</dependency>

配置文件

注意：配置文件置于项目的classpath路径下，命名为“log4j2.xml”

<? xml  version = "1.0"  encoding = "UTF-8" ?>
< Configuration  status = "WARN"  monitorInterval = "60" >
    < Appenders >
        < Console  name = "Console"  target = "SYSTEM_OUT" >  <!-- 定义类型为Console的Appender -->
            < PatternLayout  pattern = "%d{HH:mm:ss.SSS} [%level] %c{1} - %msg%n" />  <!-- 定义类型为Pattern的Layout -->
        </ Console >
    </ Appenders >
    < Loggers >
        < Root  level = "error" >  <!-- 定义Root Logger，其日志级别为error -->
            < AppenderRef  ref = "Console" />  <!-- Root Logger的Appender引用上面定义的Console -->
        </ Root >
        < Logger  name = "HelloWorld"  level = "info"  additivity = "false" >  <!-- 定义名字为HelloWorld的Logger，其日志级别为info，additivity为false -->
            < AppenderRef  ref = "Console" />  <!-- Root Logger的Appender引用上面定义的Console -->
        </ Logger >
    </ Loggers >
</ Configuration >

打印日志

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

public  class  MyClass {
    /* 获取名字为HelloWorld的Logger，若无该Logger，则根据继承结构向父节点寻找，直到找到Root Logger为止 */
    private  static  final  Logger HELLO_LOGGER = LoggerFactory.getLogger( "HelloWorld" );
    public  void  method() {
        HELLO_LOGGER.info( "Hello World!" );  // 打印日志信息
    }
}