RollingFileAppender

http://logback.qos.ch/manual/appenders.html#RollingFileAppender

1.基于时间的滚动策略

TimeBasedRollingPolicy

就好比一个小车，推着走。车身所压的时间就是要保留日志的时间。

<configuration>
    <appender name="FILE"
        class="ch.qos.logback.core.rolling.RollingFileAppender">

        <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
            <!-- daily rollover -->
            <fileNamePattern>${catalina.base}/logs/${CONTEXT_NAME}/%d{yyyy-MM-dd}/logFile.%d{yyyy-MM-dd}.log
            </fileNamePattern>
            <!-- keep 30 days‘ worth of history -->
            <maxHistory>30</maxHistory>
        </rollingPolicy>

        <encoder>
            <pattern>%-4relative [%thread] %-5level %logger{35} - %msg%n
            </pattern>
        </encoder>
    </appender>

    <root level="DEBUG">
        <appender-ref ref="FILE" />
    </root>
</configuration>

2.基于大小和时间的文件命名和触发策略

http://logback.qos.ch/manual/appenders.html#SizeAndTimeBasedFNATP

FNATP means File Naming And Triggering Policy

达到最大值便压缩；可根据每天时间变化生成文件夹。

可以设置两个rolling ：INFO 和 ERROR .

<configuration>
  <appender name="ROLLING" class="ch.qos.logback.core.rolling.RollingFileAppender">
    <rollingPolicy class="ch.qos.logback.core.rolling.TimeBasedRollingPolicy">
      <!-- rollover daily -->
      <fileNamePattern>${catalina.base}/logs/${CONTEXT_NAME}/%d{yyyy-MM-dd}/mylog-%d{yyyy-MM-dd}.%i.log.gz</fileNamePattern>
      <timeBasedFileNamingAndTriggeringPolicy
            class="ch.qos.logback.core.rolling.SizeAndTimeBasedFNATP">
        <!-- or whenever the file size reaches 100MB -->
        <maxFileSize>1mb</maxFileSize>
      </timeBasedFileNamingAndTriggeringPolicy>
    </rollingPolicy>
    <encoder>
      <pattern>%msg%n</pattern>
    </encoder>
  </appender>

  <root level="DEBUG">
    <appender-ref ref="ROLLING" />
  </root>

</configuration>

由以下代码可知，不加单位为byte, 单位只能加kb、mb、gb ，不区分大小写。

 if (unitStr.equalsIgnoreCase("")) {
        coefficient = 1;
      } else if (unitStr.equalsIgnoreCase("kb")) {
        coefficient = KB_COEFFICIENT;
      } else if (unitStr.equalsIgnoreCase("mb")) {
        coefficient = MB_COEFFICIENT;
      } else if (unitStr.equalsIgnoreCase("gb")) {
        coefficient = GB_COEFFICIENT;
      } else {
        throw new IllegalStateException("Unexpected " + unitStr);
      }
      return new FileSize(lenValue * coefficient);

注：1、 2 策略不能混用，因为不能同时生效