如何在 Log4j2 中使用编程配置添加 OutputStream？

Question

知道如何将我的输出流添加到构建配置吗？

ConfigurationBuilder<BuiltConfiguration> builder = 
ConfigurationBuilderFactory.newConfigurationBuilder();
    
AppenderComponentBuilder osAppender = builder.newAppender("os", "OutputStream");
osAppender.addAttribute("target", myStream);
builder.add(osAppender);
    
BuiltConfiguration config = builder.build();
Configurator.initialize(config);

这是我收到的错误消息：

2022-01-27 15:04:41,203 main ERROR OutputStream contains an invalid element or attribute "target"
2022-01-27 15:04:41,227 main ERROR Could not create plugin of type class org.apache.logging.log4j.core.appender.OutputStreamAppender for element OutputStream: java.lang.NullPointerException java.lang.NullPointerException
at org.apache.logging.log4j.core.appender.OutputStreamAppender.getManager(OutputStreamAppender.java:159)

谢谢

Answer 1

ConfigurationBuilder API 不允许您将无法序列化的属性设置为 String。因此，您需要直接使用 OutputSreamAppender 的构建器：

  final LoggerContext ctx = (LoggerContext) LogManager.getContext(false);
  final Configuration config = ctx.getConfiguration();
  final Appender appender = OutputStreamAppender.newBuilder()//
                                                .setTarget(myStream)
                                                .setConfiguration(ctx.getConfiguration())
                                                .build();
  config.addLoggerAppender(ctx.getRootLogger(), appender);

有关 ConfigurationBuilder API 与直接实例化 Log4j 组件的另一个示例，请参见 this question。

另请检查 Log4j's architecture，它解释了所有这些组件如何协同工作。

如何在 Log4j2 中使用编程配置添加 OutputStream？

How Can I Add The OutputStream Using Programmatical Configuration in Log4j2?

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log4j2