关于Spring Boot报错：LoggerFactory is not a Logback LoggerContext but Logback is on the classpath

1. The phenomenon of the problem

1. When using spring-boot-starter-web to refactor the project, an error is reported:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/mou/.m2/repository/org/slf4j/slf4j-log4j12/1.7.30/slf4j-log4j12-1.7.30.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/mou/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.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 [org.slf4j.impl.Log4jLoggerFactory]
Exception in thread "main" java.lang.IllegalArgumentException: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (class org.slf4j.impl.Log4jLoggerFactory loaded from file:/C:/Users/mou/.m2/repository/org/slf4j/slf4j-log4j12/1.7.30/slf4j-log4j12-1.7.30.jar). If you are using WebLogic you will need to add 'org.slf4j' to prefer-application-packages in WEB-INF/weblogic.xml: org.slf4j.impl.Log4jLoggerFactory
	at org.springframework.util.Assert.instanceCheckFailed(Assert.java:702)
	at org.springframework.util.Assert.isInstanceOf(Assert.java:602)

Two, the solution

Reason: The content of the conflict should refer to the conflict between my old project and the slf4j package that comes with Spring Boot.
Solution: Remove the log dependency in the Spring Boot Web starter

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
			<exclusions>
				<exclusion>
					<groupId>org.slf4j</groupId>
					<artifactId>slf4j-log4j12</artifactId>
				</exclusion>
				<exclusion>
					<groupId>ch.qos.logback</groupId>
					<artifactId>logback-classic</artifactId>
				</exclusion>
			</exclusions>
		</dependency>

3. Investigation method

The IDEA development tool can right-click the POM file to view the imported dependencies, and then press ctrl+F to view the location of the dependencies.