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

-------------------- 20190606 补充 -----------

     <appender name="FILE" class="ch.qos.logback.core.rolling.RollingFileAppender">
        <rollingPolicy class="ch.qos.logback.core.rolling.SizeAndTimeBasedRollingPolicy">
            <!-- daily rollover -->
            <fileNamePattern>D://data/fix.%d{yyyy-MM-dd-HH-mm}.%i.log.gz
            </fileNamePattern>
            <!-- 保留30（时间单位） -->
            <maxHistory>30</maxHistory>
            <!-- 单个文件最大 -->
            <maxFileSize>20MB</maxFileSize>
            <!-- 压缩后的fix文件总量，必须大于maxFileSize -->
            <totalSizeCap>20MB</totalSizeCap>
        </rollingPolicy>
        <encoder>
            <pattern>%d{yyyy-MM-dd HH:mm:ss} [%thread]%-5level%logger{50} - %msg%n</pattern>
        </encoder>
    </appender>

https://logback.qos.ch/manual/appenders.html

    /**
     * Given the FileNamePattern string, this method determines the compression
     * mode depending on last letters of the fileNamePatternStr. Patterns ending
     * with .gz imply GZIP compression, endings with '.zip' imply ZIP compression.
     * Otherwise and by default, there is no compression.
     * 
     */
    protected void determineCompressionMode() {
        if (fileNamePatternStr.endsWith(".gz")) {
            addInfo("Will use gz compression");
            compressionMode = CompressionMode.GZ;
        } else if (fileNamePatternStr.endsWith(".zip")) {
            addInfo("Will use zip compression");
            compressionMode = CompressionMode.ZIP;
        } else {
            addInfo("No compression will be used");
            compressionMode = CompressionMode.NONE;
        }
    }

%d 按时间命名 i% 在之前基础上命名 以gz结尾就是gzip压缩