Springboot项目log4j与logback的Jar包冲突问题
异常信息关键词：
SLF4J: Class path contains multiple SLF4J bindings.ERROR in ch.qos.logback.core.joran.spi.Interpreter@24:14 - no applicable action for [properties], current ElementPath is [[configuration][properties]]详细异常信息：
Connected to the target VM, address: '127.0.0.1:52687', transport: 'socket'
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/xx/.m2/repository/ch/qos/logback/logback-classic/1.2.11/logback-classic-1.2.11.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/xx/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.17.2/log4j-slf4j-impl-2.17.2.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.xml'
java.lang.IllegalStateException: Logback configuration error detected:
ERROR in ch.qos.logback.core.joran.spi.Interpreter@24:14 - no applicable action for [properties], current ElementPath is [[configuration][properties]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@26:29 - no applicable action for [property], current ElementPath is [[configuration][properties][property]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@28:31 - no applicable action for [property], current ElementPath is [[configuration][properties][property]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@29:33 - no applicable action for [property], current ElementPath is [[configuration][properties][property]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@30:36 - no applicable action for [property], current ElementPath is [[configuration][properties][property]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@32:13 - no applicable action for [appenders], current ElementPath is [[configuration][appenders]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@34:47 - no applicable action for [Console], current ElementPath is [[configuration][appenders][Console]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@37:71 - no applicable action for [ThresholdFilter], current ElementPath is [[configuration][appenders][Console][ThresholdFilter]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@38:44 - no applicable action for [PatternLayout], current ElementPath is [[configuration][appenders][Console][PatternLayout]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@47:79 - no applicable action for [RollingFile], current ElementPath is [[configuration][appenders][RollingFile]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@48:44 - no applicable action for [PatternLayout], current ElementPath is [[configuration][appenders][RollingFile][PatternLayout]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@49:14 - no applicable action for [Policies], current ElementPath is [[configuration][appenders][RollingFile][Policies]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@53:46 - no applicable action for [SizeBasedTriggeringPolicy], current ElementPath is [[configuration][appenders][RollingFile][Policies][SizeBasedTriggeringPolicy]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@56:39 - no applicable action for [DefaultRolloverStrategy], current ElementPath is [[configuration][appenders][RollingFile][DefaultRolloverStrategy]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@59:11 - no applicable action for [loggers], current ElementPath is [[configuration][loggers]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@61:80 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@62:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@64:109 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@65:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@67:81 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@68:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@71:79 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@72:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@74:71 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@75:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@77:87 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@78:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@80:88 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@81:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@83:80 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@84:77 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@85:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@87:84 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@88:77 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@89:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@92:55 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@93:57 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@94:65 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@95:56 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@96:64 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@97:68 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@98:64 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@99:76 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@100:72 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@101:67 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@102:52 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@103:65 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@104:66 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@105:66 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@106:62 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@107:79 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@110:61 - no applicable action for [Logger], current ElementPath is [[configuration][loggers][Logger]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@111:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@112:29 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][Logger][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@116:23 - no applicable action for [root], current ElementPath is [[configuration][loggers][root]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@117:33 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][root][appender-ref]]
ERROR in ch.qos.logback.core.joran.spi.Interpreter@119:29 - no applicable action for [appender-ref], current ElementPath is [[configuration][loggers][root][appender-ref]]at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:179)at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithSpecificConfig(AbstractLoggingSystem.java:66)at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:57)at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:132)at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:332)at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:298)at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:176)at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:169)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:143)at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:131)at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:85)at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:66)at java.util.ArrayList.forEach(ArrayList.java:1257)
异常信息告诉我们是jar包冲突导致，解决办法很简单，异常信息里面有个官网的地址，说明了解决方式，如下图：
访问地址：
http://www.slf4j.org/codes.html#multiple_bindings传送门：SLF4J Error Codes
http://www.slf4j.org/codes.html#multiple_bindings
解决方式是指定使用的jar包，排除另一个不用的即可。
麻烦的是怎么找到导致jar冲突的依赖。
继续查看异常信息，提示了冲突的2个jar包的信息，如下截图：logback-classic和log4j-slf4j-impl。
查找jar依赖关系可以通过IDEA的maven插件，如下图直接搜索：
找到了相应的依赖包。
也可以通过树状结构查看，不如直接搜索来的直观：
或者通过maven命令查找：
dependency:tree -Dverbose -Dincludes=ch.qos.logback找到导致冲突的依赖jar包，问题就好解决了，我这里是spring-boot-starter-test包导致的，直接排除springboot自带的logback即可，clean后运行项目可以正常启动了。
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope><!-- 排除自带的logback依赖 --><exclusions><exclusion><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-logging</artifactId></exclusion></exclusions>
</dependency>每个项目导致的原因可能各不相同，这是我遇到的一次jar包冲突供参考。