Question

我尝试了Extending Log4j2和Create Custom Pattern using log4j2 in java中的示例，现在我想在日志中添加两个字段。为了得到这个，我需要做些什么改变？

Answer 1

请参阅本手册https://logging.apache.org/log4j/log4j-2.2/manual/plugins.html#Converters

如果您想要多个字段，例如时间和名称，您可以创建两个单独的转换器，将这些数据提供给日志。

例如，您有 MyNamePatternConverter ，在这里我们可以提供别名 whatIsMyName 和 myName 。在日志模式中，我们可以使用其中任何一种。

@Plugin(name="MyNamePatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys(value = {"whatIsMyName", "myName"})
public class MyNameConverter extends LogEventPatternConverter {

    protected MyNameConverter(String name, String style) {
        super(name, style);
    }

    public static MyNameConverter newInstance(String[] options) {
        return new MyNameConverter("My name Converter", "name");
    }

    public void format(LogEvent event, StringBuilder toAppendTo) {
        toAppendTo.append("Yuriy");
    }
}

和 TimePatternConverter

@Plugin(name = "TimePatternConverter", category = PatternConverter.CATEGORY)
@ConverterKeys(value = {"timeIsNow", "timeNow", "now"})
public class TimeConverter extends LogEventPatternConverter {
    protected TimeConverter(String name, String style) {
        super(name, style);
    }

    public static TimeConverter newInstance(String[] options) {
        return new TimeConverter("Time Converter", "now");
    }

    public void format(LogEvent logEvent, StringBuilder toAppendTo) {
        toAppendTo.append(new SimpleDateFormat("HH:mm").format(new Date()));
    }
}

我们将把它们放在名为 converter 的单独包中。

<?xml version="1.0" encoding="UTF-8"?>
<Configuration xmlns="http://logging.apache.org/log4j/2.0/config"
               status="OFF" packages="converters">
    <Appenders>
        <Console name="STDOUT" target="SYSTEM_OUT">
            <PatternLayout pattern="Time is now %timeIsNow and my name is %whatIsMyName, %m%n"/>
        </Console>
    </Appenders>
    <Loggers>
        <Logger name="org.apache.log4j.xml" level="all" />
        <Root level="all">
            <AppenderRef ref="STDOUT" />
        </Root>
    </Loggers>
</Configuration>

提供log4j2.xml。

创建一个示例Main类来测试它。

public class Main {
    private static final Logger logger = LogManager.getLogger(ResolverUtil.Test.class);
    public static void main(String[] args) {
        logger.info("Hello log4j2");
        logger.debug("This is debug message");
    }
}

这将产生这样的输出：

Time is now 20:40 and my name is Yuriy, Hello log4j2
Time is now 20:40 and my name is Yuriy, This is debug message

Java Log4j2转换器类别插件添加多个自定义字段进行记录

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