springboot继承log4j2完美实践

1.引入jar

   <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <exclusions>
                <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.配置yml，读取外部log配置

logging:
  config: classpath:log4j2-spring.xml

3.配置日志文件log4j-spring.xml

<?xml version="1.0" encoding="UTF-8"?>
<configuration>
    <appenders>
        <!--这个输出控制台的配置-->
        <Console name="Console" target="SYSTEM_OUT">
            <!--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="INFO" onMatch="ACCEPT" onMismatch="DENY" />
            <!--这个都知道是输出日志的格式-->
            <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %class{36} %L %M - %msg%xEx%n" />
        </Console>
        <!--文件会打印出所有信息，这个log每次运行程序会自动清空，由append属性决定，这个也挺有用的，适合临时测试用-->
        <File name="log" fileName="C:/Users/Administrator/Desktop/logs/fastboot/test.log" append="false">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} %-5level %class{36} %L %M - %msg%xEx%n" />
        </File>
        <!-- 这个会打印出所有的信息，每次大小超过size，则这size大小的日志会自动存入按年份-月份建立的文件夹下面并进行压缩，作为存档-->
        <RollingFile name="RollingFile" fileName="C:/Users/Administrator/Desktop/logs/fastboot/test_111.log" filePattern="C:/Users/Administrator/Desktop/logs/fastboot/$${date:yyyy-MM}/app-%d{MM-dd-yyyy}-%i.log">
            <PatternLayout pattern="%d{yyyy-MM-dd 'at' HH:mm:ss z} %-5level %class{36} %L %M - %msg%xEx%n" />
            <SizeBasedTriggeringPolicy size="100MB" />
        </RollingFile>
    </appenders>

    <!--然后定义logger，只有定义了logger并引入的appender，appender才会生效-->
    <loggers>
        <root level="info">
            <appender-ref ref="Console" />
            <appender-ref ref="log" />
            <appender-ref ref="RollingFile" />
        </root>
    </loggers>
</configuration>

附上会遇到的问题：

1.启动报错

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/E:/apache-maven-repo/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/E:/apache-maven-repo/org/apache/logging/log4j/log4j-slf4j-impl/2.11.2/log4j-slf4j-impl-2.11.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
Logging system failed to initialize using configuration from 'classpath:log4j2-spring.xml'
java.lang.IllegalStateException: Logback configuration error detected: 
ERROR in ch.qos.logback.core.joran.spi.Interpreter@3:16 - no applicable action for [appenders], current ElementPath  is [[configuration][appenders]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@5:53 - no applicable action for [Console], current ElementPath  is [[configuration][appenders][Console]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@7:80 - no applicable action for [ThresholdFilter], current ElementPath  is [[configuration][appenders][Console][ThresholdFilter]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@9:96 - no applicable action for [PatternLayout], current ElementPath  is [[configuration][appenders][Console][PatternLayout]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@12:106 - no applicable action for [File], current ElementPath  is [[configuration][appenders][File]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@13:96 - no applicable action for [PatternLayout], current ElementPath  is [[configuration][appenders][File][PatternLayout]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@16:179 - no applicable action for [RollingFile], current ElementPath  is [[configuration][appenders][RollingFile]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@17:110 - no applicable action for [PatternLayout], current ElementPath  is [[configuration][appenders][RollingFile][PatternLayout]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@18:55 - no applicable action for [SizeBasedTriggeringPolicy], current ElementPath  is [[configuration][appenders][RollingFile][SizeBasedTriggeringPolicy]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@23:14 - no applicable action for [loggers], current ElementPath  is [[configuration][loggers]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@24:28 - no applicable action for [root], current ElementPath  is [[configuration][loggers][root]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@25:43 - no applicable action for [appender-ref], current ElementPath  is [[configuration][loggers][root][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@26:39 - no applicable action for [appender-ref], current ElementPath  is [[configuration][loggers][root][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@27:47 - no applicable action for [appender-ref], current ElementPath  is [[configuration][loggers][root][appender-ref]]

这个报错问题解决办法：

（1）同时引用了好几种日志jar，这里使用log4j2，所以在pom.xml文件中右击选择Diagrams，查看依赖图，找到spring.boot.starter-logging依赖，删除即可。

如果你删除了，还是有这个报错，那就是没有删除干净。

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/E:/apache-maven-repo/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/E:/apache-maven-repo/org/apache/logging/log4j/log4j-slf4j-impl/2.11.2/log4j-slf4j-impl-2.11.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]

这个报错的意思是SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder] 绑定

logging有多个绑定，logback、log4j2两种日志同时存在；目前使用的是logback的绑定。