Quartz Official Website Example unable to output log

Quartz the latest version of MAVEN configuration, the official website to the code as follows:

	          <dependency>
			<groupId>org.quartz-scheduler</groupId>
			<artifactid>quartz</ artifactid>
			<version>2.2.1</version>
		</dependency>
		

However, because logging is logged with SLF4J, the log cannot be exported, and to output the log, you need to add a reference to SLF4J later:

                 <dependency>
			<groupId>org.slf4j</groupId>
			<artifactid>slf4j-log4j12</ artifactid>
			<version>1.7.2</version>
		</dependency>