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又是我們需要開啟debug來排查故障，只需在項目目錄下創建檔案 WEB-INF/classes/log4j.properties 內容如下
log4j.rootLogger=debug,console,file
重新啟動tomcat將進入Debug模式，你將看到大量的調試信息。
1) log4j.properties: Add the console to the root logger
log4j.rootLogger = INFO, CATALINA, CONSOLE
2) log4j.properties: Change the DailyRollingFileAppender to:
log4j.appender.CATALINA=org.apache.log4j.rolling.RollingFileAppender
log4j.appender.CATALINA.RollingPolicy=org.apache.log4j.rolling.TimeBasedRollingPolicy
log4j.appender.CATALINA.RollingPolicy.FileNamePattern=${catalina.base}/logs/catalina.%d{yyyy-MM-dd}.log