如何在 log4j2 中配置 null appender

Question

Log4j 1.* 有一个 null appender class，但我找不到 log4j 2 中的等效项。有吗？如何在 log4j2.xml 中配置空附加程序？

Answer 1

NullAppendar 基本上是一个（几乎）empty implementation of the Appender interface, using the AppenderSkeleton as a base class. Doing the same in Log4j2 is trivial, but you'll need some boilerplate code to make it work, see the Apache documentation on custom appenders。

@Plugin(name = "NullAppender", category = "Core", elementType = "appender", printObject = true)
public class NullAppender extends AbstractAppender {

    private static final long serialVersionUID = -701612541126635333L;

    private NullAppender(String name, Filter filter, Layout<? extends Serializable> layout) {
        super(name, filter, layout);    
    }

    @Override
    public void append(LogEvent event) {
        // do exactly nothing
    }

    // blatantly stolen from the Apache doc, all errors (C) by me
    @PluginFactory
    public static NullAppender createAppender(@PluginAttribute("name") String name,
                                              @PluginElement("Layout") Layout layout,
                                              @PluginElement("Filters") Filter filter) {

        if (name == null) {
            LOGGER.error("No name provided for NullAppender");
            return null;
        }

        if (layout == null) {
            layout = PatternLayout.createDefaultLayout();
        }
        return new NullAppender(name, filter, layout);
    }

}

Answer 2

使用 CountingNoOp 附加程序。

<Appenders>
  <CountingNoOp name="DEV_NULL" />
</Appenders>

Answer 3

从 Log4j2 版本 2.7 开始，有一个 NullAppender class。早期版本没有它。它在配置文件中使用的名称是 "Null"。它可以像这样添加到 Appenders 列表中：

<Appenders>
  <Null name="arbritrary_name" />
</Appenders>

如何在 log4j2 中配置 null appender

How to configure null appender in log4j2

java

log4j

log4j2

appender