Spring Boot日志系统默认使用的是logback，灵活性不高，很多时候我们需要使用log4j。集成方法很简单在maven依赖中加入：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j</artifactId>
</dependency>
如果想集成log4j2，只需要将spring-boot-starter-log4j改为spring-boot-starter-log4j2即可
附：log4j.properties配置示例
# Output pattern : date [thread] priority category - message
log4j.rootLogger=WARN, Console, RollingFile
#Console
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
#RollingFile
log4j.appender.RollingFile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.RollingFile.File=logs/speedy.log
log4j.appender.RollingFile.layout=org.apache.log4j.PatternLayout
log4j.appender.RollingFile.layout.ConversionPattern=%d [%t] %-5p [%c] - %m%n
