版本信息：

spring cloud 版本Greenwich.SR2
spring boot 版本2.1.8.RELEASE

官网文档：

** http://logging.apache.org/log4j/2.x/manual/configuration.html **

以下每个步骤不可缺失

1. pom.xml配置
   需要排除spring-boot-starter自带的logback依赖，不然日志无法记录在日志文件里

   <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
        <exclusions>
            <!-- 排除自带的logback依赖 -->
            <exclusion>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-logging</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>

2. log4j配置
   新建log4j.xml放在resources目录下
   设置console，InfoLog，ErrorLog的输出配置以及日志目录

   Configuration status="INFO" 设置的是console的输出级别

   <?xml version="1.0" encoding="UTF-8"?>
    <Configuration status="INFO">
        <Appenders>
            <!--添加一个控制台追加器-->
            <Console name="Console" target="SYSTEM_OUT" follow="true">
                <PatternLayout>
                    <pattern>[%-5p] %d %c - %m%n</pattern>
                </PatternLayout>
            </Console>
   
            <!-- info log -->
            <RollingFile name="InfoLog" fileName="/opt/logs/scm-warehouse/info.log"
                         filePattern="/opt/logs/scm-warehouse/info-%d{yyyy-MM-dd}.log">
                <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} %-5level %class{36}.%M[%L] - %msg%xEx%n"/>  
                <Policies>
                    <TimeBasedTriggeringPolicy modulate="true" interval="1"/>
                </Policies>
                <Filters>
                    <ThresholdFilter level="warn" onMatch="DENY" onMismatch="NEUTRAL"/> 
                    <ThresholdFilter level="info" onMatch="ACCEPT" onMismatch="DENY" />
                </Filters> 
            </RollingFile>
   
            <!-- error log -->
            <RollingFile name="ErrorLog" fileName="/opt/logs/scm-warehouse/error.log"
                         filePattern="/opt/logs/scm-warehouse/error-%d{yyyy-MM-dd}.log">
                <PatternLayout pattern="%d{yyyy-MM-dd HH:mm:ss} [%-5level] %class{36}.%M[%L] - %msg%xEx%n"/>  
                <Policies>
                    <TimeBasedTriggeringPolicy modulate="true" interval="1"/>
                </Policies>
                <ThresholdFilter level="error" onMatch="ACCEPT" onMismatch="DENY" />  
            </RollingFile>            
        </Appenders>
        <Loggers>
            <Root level="info">
                <AppenderRef ref="Console" />
                <AppenderRef ref="InfoLog" />
                <AppenderRef ref="ErrorLog" />
            </Root>
        </Loggers>
    </Configuration>

3. yml配置，指定配置

   logging:
      config: classpath:log4j.xml
      level:
        root: info

4. java代码内使用

   import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    private static Logger logger = LoggerFactory.getLogger(XXXclass.class);
    logger.info("xxx);