Log4j2 could not find a logging implementation

错误信息:

Log4j2 could not find a logging implementation. Please add log4j-core to the classpath

解决办法:
pom把log4j-api也加进去

 <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-core</artifactId>
            <version>2.9.1</version>
        </dependency>
        <dependency>
            <groupId>org.apache.logging.log4j</groupId>
            <artifactId>log4j-api</artifactId>
            <version>2.9.1</version>
        </dependency>