Log4j 2中的单独错误记录

Question

Log4j 2允许将类别和行信息包含在日志条目中。 但是，作者声称创建该条目需要花费4至5倍的时间。

我日志的99.5％由正常操作条目（info）组成，而实际上并不需要行和类。 我想知道是否有任何方法可以配置log4j 2，使其仅将文件，类和行包含到具有“警告”或更高级别的条目中？

Answer 1

本地似乎不支持此功能。 但是，您可以使用自己的过滤器实现和2个附加程序来归档所需的结果。

每个附加器仅输出一定范围的级别，严重事件的附加器可以添加行号。 记录器需要同时使用两个追加程序，以免您处理代码中的区别，即记录如下：

// Will have line numbers in output.
LogManager.getLogger().error("bla");
// Won't have line numbers in output.
LogManager.getLogger().info("blub");

Log4j 2的配置类似于（注意ConsoleMoreSevere %line ）：

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" packages="yield.log4j2">
    <Appenders>
        <Console name="ConsoleLessSevere" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{ISO8601} [%t] %-5level %logger{36} - %msg%n" />
            <LevelRangeFilter maxLevel="INFO"/>
        </Console>
        <Console name="ConsoleMoreSevere" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{ISO8601} [%t] %-5level %logger{36}:%line - %msg%n" />
            <LevelRangeFilter minLevel="WARN"/>
        </Console>
    </Appenders>
    <Loggers>
        <Root level="WARN">
            <AppenderRef ref="ConsoleLessSevere" />
            <AppenderRef ref="ConsoleMoreSevere" />
        </Root>
    </Loggers>
</Configuration>

这就需要定义自定义过滤器实现，在我的示例中称为yield.log4j2.LevelRangeFilter 。 该实现是根据Log4j 2文档中的示例建模的 ，可以在https://github.com/AugustusKling/yield/blob/master/src/main/java/yield/log4j2/LevelRangeFilter.java中找到。 随时复制课程。

为了在没有外部资源的情况下完成此答案，请执行LevelRangeFilter的实现：

package yield.log4j2;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.Logger;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.filter.AbstractFilter;
import org.apache.logging.log4j.message.Message;

/**
 * Filters log events within given bounds.
 */
@Plugin(name = "LevelRangeFilter", category = "Core", elementType = "filter", printObject = true)
public class LevelRangeFilter extends AbstractFilter {
    private final Level minLevel;
    private final Level maxLevel;

    private LevelRangeFilter(final Level minLevel, final Level maxLevel,
            final Result onMatch, final Result onMismatch) {
        super(onMatch, onMismatch);
        this.minLevel = minLevel;
        this.maxLevel = maxLevel;
    }

    @Override
    public Result filter(final Logger logger, final Level level,
            final Marker marker, final String msg, final Object... params) {
        return filter(level);
    }

    @Override
    public Result filter(final Logger logger, final Level level,
            final Marker marker, final Object msg, final Throwable t) {
        return filter(level);
    }

    @Override
    public Result filter(final Logger logger, final Level level,
            final Marker marker, final Message msg, final Throwable t) {
        return filter(level);
    }

    @Override
    public Result filter(final LogEvent event) {
        return filter(event.getLevel());
    }

    private Result filter(final Level level) {
        if (maxLevel.intLevel() <= level.intLevel()
                && minLevel.intLevel() >= level.intLevel()) {
            return onMatch;
        } else {
            return onMismatch;
        }
    }

    /**
     * @param minLevel
     *            Minimum log Level.
     * @param maxLevel
     *            Maximum log level.
     * @param onMatch
     *            Action to take on a match.
     * @param onMismatch
     *            Action to take on a mismatch.
     * @return The created filter.
     */
    @PluginFactory
    public static LevelRangeFilter createFilter(
            @PluginAttribute(value = "minLevel", defaultString = "TRACE") final Level minLevel,
            @PluginAttribute(value = "maxLevel", defaultString = "FATAL") final Level maxLevel,
            @PluginAttribute(value = "onMatch", defaultString = "NEUTRAL") final Result onMatch,
            @PluginAttribute(value = "onMismatch", defaultString = "DENY") final Result onMismatch) {
        return new LevelRangeFilter(minLevel, maxLevel, onMatch, onMismatch);
    }
}

Answer 2

从RC2开始，Log4j2不提供这种功能。 您可以为此在log4j2 Jira问题跟踪器上提出功能请求。

同时，您是否要包含位置信息的控制权以每个记录器为基础。 因此，一个想法可能是拥有一个配置为includeLocation="true"的单个系统级FATAL级记录器。

配置片段示例：

  ...
  <Loggers>
    <AsyncLogger name="FATAL_LOGGER" level="fatal" includeLocation="true" additivity="false">
      <AppenderRef ref="someAppender"/>
    </AsyncLogger>
    <Root level="trace" includeLocation="false">
      <AppenderRef ref="someAppender"/>
    </Root>
  </Loggers>
</Configuration>

用法示例：

public class MyApp {
  private static final Logger logger = LogManager.getLogger(MyApp.class);

  public void someMethod(int value) {
    // normal trace-level logging does not include location info
    logger.trace("Doing some work with param {}", value);
    try {
      callAnotherMethod();
    } catch (Throwable t) {
      // use the shared fatal logger to include location info
      LogManager.getLogger("FATAL_LOGGER").fatal("Unexpected error", t);
    }
  }
}