log4j.xml example

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration debug="true"
    xmlns:log4j='http://jakarta.apache.org/log4j/'>

    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <layout class="org.apache.log4j.PatternLayout">
        <param name="ConversionPattern"
          value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n" />
        </layout>
    </appender>

    <root>
        <level value="DEBUG" />
        <appender-ref ref="console" />
    </root>

</log4j:configuration>

http://logging.apache.org/log4j/1.2/manual.html

https://logging.apache.org/log4net/release/manual/configuration.html

如果要配置除 root logger 以外的普通 logger ，需要配置 <logger name="这里是你的java package"

且name 不能同名