java日志输出级别问题请教

目前该配置可以输出>=INFO级别的日志信息，如何设置可以显示>=DEBUG的日志信息呢？求教？
一、log4j.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE log4j:configuration PUBLIC "-//APACHE//DTD LOG4J 1.2//EN" "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
    <!-- 1、Appenders -->
    <!--日志输出到控制台-->
    <appender name="console" class="org.apache.log4j.ConsoleAppender">
        <param name="Target" value="System.out"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c - %m%n"/>
        </layout>
    </appender>
    <!--日志输出到文件中-->
    <!--每天产生一个日志文件，文件所在位置为项目目录下面的logs文件夹中，文件名为server.log-->
    <appender name="file" class="org.apache.log4j.DailyRollingFileAppender">
        <param name="File" value="logs/server.log"/>
        <param name="DatePattern" value="'.'yyyy-MM-dd'.log'"/>
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern" value="[%d{yyyy-MM-dd HH:mm:ss.SSS\} %-5p] [%t] %c{3\} - %m%n"/>
        </layout>
    </appender>
    <!--2、Application Logs-->
    <logger name="com.zhoujie">
        <level value="info"/>
    </logger>
    <!-- 3rdparty Loggers -->
    <logger name="org.springframework.core">
        <level value="info"/>
    </logger>
    <logger name="org.springframework.beans">
        <level value="info"/>
    </logger>
    <logger name="org.springframework.context">
        <level value="info"/>
    </logger>
    <logger name="org.springframework.web">
        <level value="info"/>
    </logger>
    <logger name="org.springframework.jdbc">
        <level value="info"/>
    </logger>
    <logger name="org.mybatis.spring">
        <level value="info"/>
    </logger>
    <logger name="java.sql">
        <level value="info"/>
    </logger>
    <logger name="java.sql">
        <level value="info"/>
    </logger>
    <logger name="net.sf.ehcache.store.disk.Segment">
        <level value="warn"/>
    </logger>
    <!--Root Logger-->
    <root>
        <priority value="debug"/>
        <appender-ref ref="console"/>
        <appender-ref ref="file"/>
    </root>
</log4j:configuration>

二、测试代码

package com.zhoujie;


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

public class Log {
    //public static LoggerFactory factory = new LoggerFactory(Log.class);
    //private static Logger logger = LoggerFactory.getLogger(Log.class);
    public static Logger logger = LoggerFactory.getLogger(Log.class);

    public static void main(String[] args) {
        //输出>=INFO级别的消息
        logger.info("Hello World");
        logger.debug("Hello Java");
        logger.warn("Hello Game");
        logger.info("你好！禹尧");
    }
}
三、控制台输出

2018-11-14 16:46:39 INFO com.zhoujie.Log - Hello World
2018-11-14 16:46:39 WARN com.zhoujie.Log - Hello Game
2018-11-14 16:46:39 INFO com.zhoujie.Log - 你好！禹尧

四、文件输出