Tomcat下使用Log4j 接管 catalina.out 日志文件生成方式，按天存放，解决catalina.out日志文件过大问题
1. 准备jar包：
log4j-1.2.17.jar （从 http://www.apache.org/dist/logging/log4j/1.2.17/ 下载）
tomcat-juli.jar, tomcat-juli-adapters.jar （从 http://www.apache.org/dist/tomcat/tomcat-7/v7.0.52/bin/extras/ 下载，根据你的Tomcat版本选择对应的分支）
2. 将上面的三个jar包拷贝到 Tomcat 的 lib 目录下；
3. 将 tomcat-juli.jar 拷贝到 Tomcat 的 bin 目录下，替换原有的jar包；
4. 修改 Tomcat 的 conf/context.xml 文件，将<Context>为<Context swallowOutput="true">
（增加 swallowOutput="true" 的属性配置，只有这样才能完全的把tomcat的stdout给接管过来。这一步很关键 在官网及网上找了许多资料都没有提及。）；
5. 删除 Tomcat 的 conf/logging.properties 文件（或者重命名-建议）；
6. 在 Tomcat 的 lib 目录下创建 log4j.properties 文件：
log4j.rootLogger=INFO, CATALINA
# Define all the appenders
log4j.appender.CATALINA=org.apache.log4j.DailyRollingFileAppender
log4j.appender.CATALINA.File=${catalina.base}/logs/catalina.
log4j.appender.CATALINA.Append=true
log4j.appender.CATALINA.Encoding=UTF-8
# Roll-over the log once per day
log4j.appender.CATALINA.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.CATALINA.layout = org.apache.log4j.PatternLayout
log4j.appender.CATALINA.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
log4j.appender.LOCALHOST=org.apache.log4j.DailyRollingFileAppender
log4j.appender.LOCALHOST.File=${catalina.base}/logs/localhost.
log4j.appender.LOCALHOST.Append=true
log4j.appender.LOCALHOST.Encoding=UTF-8
log4j.appender.LOCALHOST.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.LOCALHOST.layout = org.apache.log4j.PatternLayout
log4j.appender.LOCALHOST.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
log4j.appender.MANAGER=org.apache.log4j.DailyRollingFileAppender
log4j.appender.MANAGER.File=${catalina.base}/logs/manager.
log4j.appender.MANAGER.Append=true
log4j.appender.MANAGER.Encoding=UTF-8
log4j.appender.MANAGER.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.MANAGER.layout = org.apache.log4j.PatternLayout
log4j.appender.MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
log4j.appender.HOST-MANAGER=org.apache.log4j.DailyRollingFileAppender
log4j.appender.HOST-MANAGER.File=${catalina.base}/logs/host-manager.
log4j.appender.HOST-MANAGER.Append=true
log4j.appender.HOST-MANAGER.Encoding=UTF-8
log4j.appender.HOST-MANAGER.DatePattern='.'yyyy-MM-dd'.log'
log4j.appender.HOST-MANAGER.layout = org.apache.log4j.PatternLayout
log4j.appender.HOST-MANAGER.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.Encoding=UTF-8
log4j.appender.CONSOLE.layout = org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern = %d [%t] %-5p %c- %m%n
# Configure which loggers log to which appenders
# Configure which loggers log to which appenders
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost]=INFO, LOCALHOST
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/manager]=\
INFO, MANAGER
log4j.logger.org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/host-manager]=\
INFO, HOST-MANAGER来源：oschina
链接：https://my.oschina.net/u/59889/blog/205669