如何过滤 log4j2 中未设置的标记？

Question

我想以记录所有没有标记的消息的方式配置 log4j2。仅当配置文件中有此标记的特殊 ACCEPT 规则时，才应记录所有带有标记的消息。

我没有找到任何可以检测“无标记集”情况的过滤规则。有没有或者我必须自己实施？

log4j2 配置的过滤器部分可能类似于以下示例，但NoMarkerFilter语句应捕获未设置标记的情况。

<Filters>
        <MarkerFilter marker="SQL_UPDATE" onMatch="ACCEPT" onMismatch="NEUTRAL" />
        <NoMarkerFilter onMatch="ACCEPT" onMismatch="DENY" />
</Filters>

Answer 1

更新 - 2019 年 7 月

NoMarkerFilter 作为 log4j 的一部分从2.12.0 版开始提供

有了这个，下面的配置将起作用：

<Filters>
        <MarkerFilter marker="SQL_UPDATE" onMatch="ACCEPT" onMismatch="NEUTRAL" />
        <NoMarkerFilter onMatch="ACCEPT" onMismatch="DENY" />
</Filters>

我遇到了类似的问题，但在 log4j2 中找不到任何此类实现。不得不自己实现一个。

@Plugin(name = "NoMarkerFilter", category = Node.CATEGORY, elementType = Filter.ELEMENT_TYPE, printObject = true)
public class NoMarkerFilter extends AbstractFilter {


  private NoMarkerFilter(final Result onMatch, final Result onMismatch) {
    super(onMatch, onMismatch);
  }

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

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

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

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

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4, final Object p5) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4, final Object p5, final Object p6) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4, final Object p5, final Object p6,
                       final Object p7) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4, final Object p5, final Object p6,
                       final Object p7, final Object p8) {
    return filter(marker);
  }

  @Override
  public Result filter(final Logger logger, final Level level, final Marker marker, final String msg,
                       final Object p0, final Object p1, final Object p2, final Object p3,
                       final Object p4, final Object p5, final Object p6,
                       final Object p7, final Object p8, final Object p9) {
    return filter(marker);
  }

  private Result filter(final Marker marker) {
    return null == marker ? onMatch : onMismatch;
  }

  /**
   * Create the NoMarkerFilter.
   *
   * @param match    The action to take if a match occurs.
   * @param mismatch The action to take if no match occurs.
   * @return A NoMarkerFilter.
   */
  @PluginFactory
  public static NoMarkerFilter createFilter(
      @PluginAttribute("onMatch") final Result match,
      @PluginAttribute("onMismatch") final Result mismatch) {
    return new NoMarkerFilter(match, mismatch);
  }
}

有了这个，下面的配置应该可以工作：

<Filters>
        <MarkerFilter marker="SQL_UPDATE" onMatch="ACCEPT" onMismatch="NEUTRAL" />
        <NoMarkerFilter onMatch="ACCEPT" onMismatch="DENY" />
</Filters>