比较全的log4j示例

<?xml version="1.0" encoding="UTF-8"?>

<configuration status="off">

    <!--先定义所有的appender -->
    <appenders>
        <!--这个输出控制台的配置 -->
        <Console name="Console" target="SYSTEM_OUT">
            <!--这个都知道是输出日志的格式 -->
            <PatternLayout pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %level [%thread][%file:%line] - %msg%n%ex" />

            <!--控制台只输出level及以上级别的信息（onMatch），其他的直接拒绝（onMismatch） -->
            <ThresholdFilter level="trace" onMatch="ACCEPT" onMismatch="DENY" />
        </Console>

        <RollingFile name="RollingFile" fileName="/log/CFDMS.log" filePattern="/log/CFDMS.%d{yyyy-MM-dd}.log">
            <PatternLayout pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %level [%thread][%file:%line] - %msg%n%ex" charset="UTF-8" />
            <ThresholdFilter level="trace" onMatch="ACCEPT" onMismatch="DENY" />
            <Policies>
                <!-- 每天一个文件 -->
                <TimeBasedTriggeringPolicy interval="1" modulate="true" />

                <!-- 保存365天的记录 -->
                <DefaultRolloverStrategy max="365" />
            </Policies>
        </RollingFile>

        <RollingFile name="RollingFileSuccess" fileName="/log/CFDMSSuccess.log" filePattern="/log/CFDMSSuccess.%d{yyyy-MM-dd}.log">
            <PatternLayout pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %level [%thread][%file:%line] - %msg%n%ex" charset="UTF-8" />
            <Filters>
                <!-- 显示error级别之外的信息 -->
                <ThresholdFilter level="error" onMatch="DENY" onMismatch="NEUTRAL"/>
                <ThresholdFilter level="trace" onMatch="ACCEPT" onMismatch="DENY"/>
            </Filters>
            <Policies>
                <!-- 每天一个文件 -->
                <TimeBasedTriggeringPolicy interval="1" modulate="true" />

                <!-- 保存365天的记录 -->
                <DefaultRolloverStrategy max="365" />
            </Policies>
        </RollingFile>

        <RollingFile name="RollingFileError" fileName="/log/CFDMSError.log" filePattern="/log/CFDMSError.%d{yyyy-MM-dd}.log">
            <PatternLayout pattern="%date{yyyy-MM-dd HH:mm:ss.SSS} %level [%thread][%file:%line] - %msg%n%ex" charset="UTF-8" />
            <Filters>
                <!-- 只显示error级别的信息 -->
                <ThresholdFilter level="error" onMatch="ACCEPT" onMismatch="DENY"/>
            </Filters>
            <Policies>
                <!-- 每天一个文件 -->
                <TimeBasedTriggeringPolicy interval="1" modulate="true" />

                <!-- 保存365天的记录 -->
                <DefaultRolloverStrategy max="365" />
            </Policies>
        </RollingFile>

        <!-- 自定义一个log文件在程序中直接使用 -->
        <RollingFile name="liuyxlog" fileName="/log/liuyx.log" append="true"
                             filePattern="/log/liuyx$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log.gz">
            <PatternLayout pattern="%d{yyyy-MM-dd 'at' HH:mm:ss z} %-5level %class{36} %L %M - %msg%xEx%n"/>
            <SizeBasedTriggeringPolicy size="4 MB"/>
        </RollingFile>
    </appenders>

    <!--然后定义logger，只有定义了logger并引入的appender，appender才会生效 -->
    <loggers>
        <!-- 3rdparty Loggers -->
        <logger name="org.springframework.core" level="warn">
        </logger>
        <logger name="org.springframework.beans" level="warn">
        </logger>
        <logger name="org.springframework.context" level="warn">
        </logger>
        <logger name="org.springframework.web" level="warn">
        </logger>
        <logger name="org.jboss.netty" level="warn">
        </logger>
        <logger name="org.apache.http" level="warn">
        </logger>
        <logger name="com.mchange.v2" level="warn">
        </logger>
        <!-- 自定义一个log文件在程序中直接使用 -->
        <logger name="liuyxlogger" additivity="TRUE" level="ALL">
            <appender-ref ref="liuyxlog" level="ALL" />
        </logger>
        <!--建立一个默认的root的logger -->
        <root level="info">
            <appender-ref ref="RollingFile" />
            <appender-ref ref="RollingFileSuccess" />
            <appender-ref ref="RollingFileError" />
            <appender-ref ref="Console" />
        </root>
    </loggers>
</configuration>

package com.inspur;

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

public class WhereIsMyLogFile {
    private static Logger logger = LogManager.getLogger("liuyxlogger");
    private static Logger logger2 = LogManager.getLogger(WhereIsMyLogFile.class);
    public static void main(String[] args) {
        logger.trace("hello liuyx log");
        logger2.info("from logger2");
        logger2.error("im an error");
    }
}

输出结果

如果想输出到tomcat根目录下，可以在路径前加上${sys:catalina.home}