java 中使用log4j

一、控制台使用

1、导入log4j包到工程中

2、配置：

log4j.rootLogger=DEBUG,console,R

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.threshold=INFO
log4j.appender.console.layout=org.apache.log4j.PatternLayout

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.Append=true
log4j.appender.R.File=main.log
log4j.appender.R.Threshold=DEBUG
log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%5p] - %c -%F(%L) -%m%n
log4j.appender.R.MaxFileSize=20MB

log4j.org.springframework.web=DEBUG

工程结构如图:

3、使用：

public class Main {

   static   org.apache.log4j.Logger logger=org.apache.log4j.LogManager.getLogger(Main.class);


    public static void main(String[] args) {
        logger.info("main");
        System.out.println("Hello World!");
    }
}

二、Java Web中使用

1、导入log4j包到工程中

2、log4j配置（同上）

3、在Web.xml中配置l加载og4j

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/applicationContext.xml,/WEB-INF/dispatcher-servlet.xml</param-value>
    </context-param>
    <context-param>
        <param-name>log4jConfigLocation</param-name>
        <param-value>/WEB-INF/log4j.properties</param-value>
    </context-param>
    <context-param>
        <param-name>log4jRefreshInterval</param-name>
        <param-value>60000</param-value>
    </context-param>
    <listener>
        <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
    </listener>
    <listener>
        <listener-class>org.springframework.web.util.Log4jConfigListener</listener-class>
    </listener>
    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>*.form</url-pattern>
    </servlet-mapping>
</web-app>