log4j:WARN No appenders could be found for logger (org.apache.hadoop.metrics2.lib.MutableMetricsFactory).
log4j:WARN Please initialize the log4j system properly.

解决方法：src/main/resources下添加log4j.properties

# Set root logger level to DEBUG and its only appender to CONSOLE.
log4j.rootLogger=INFO, CONSOLE

# CONSOLE appender is set to be a ConsoleAppender.
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender

# CONSOLE appender uses PatternLayout.
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n