Log4j2 PatternLayout¶

Log4j2 PatternLayout is a flexible configuration component that allows developers to customize the format of log output.^[600-developer__java__3-party__java-log4j2.md]

Syntax and Usage¶

In XML configurations, the PatternLayout is implemented using the <PatternLayout> element.^[600-developer__java__3-party__java-log4j2.md] The specific format of the log line is defined by the pattern attribute within this element.^[600-developer__java__3-party__java-log4j2.md]

Configuration Strategies¶

To promote consistency and maintainability across different appenders, it is a common practice to define the pattern string as a global property and then reference it.^[600-developer__java__3-party__java-log4j2.md]

For example, a property named LOG_PATTERN can be defined in the <Properties> section:^[600-developer__java__3-party__java-log4j2.md]

<Properties>
    <Property name="LOG_PATTERN">[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n</Property>
</Properties>

This property can then be reused by multiple PatternLayout instances via the ${LOG_PATTERN} syntax, ensuring that the [[Logging]] output format remains uniform whether writing to a file or the console.^[600-developer__java__3-party__java-log4j2.md]

Example¶

The following XML demonstrates a PatternLayout applied to a Console appender using the referenced property:^[600-developer__java__3-party__java-log4j2.md]

<Appenders>
    <Console name="Console" target="SYSTEM_OUT">
        <PatternLayout pattern="${LOG_PATTERN}"/>
    </Console>
</Appenders>

Sources¶

^[600-developer__java__3-party__java-log4j2.md]