在Java中启动Log4j2 RollingFileAppender

Question

我用的是log4j2

我想创建一个RollingFileAppender，它每天旋转日志文件。 在应用程序启动之前，日志文件的名称是未知的（日志文件名由应用程序配置组装而成）

这就是为什么我需要在运行时添加RollingFileAppender

我有以下代码：

public static final ConfigurationBuilder<BuiltConfiguration> BUILDER = ConfigurationBuilderFactory.newConfigurationBuilder

public void initFileLoggerWithFilePattern(final String pattern) {
   final LoggerComponentBuilder   logger   = BUILDER.newLogger("FileLogger", Level.DEBUG);
   final AppenderComponentBuilder appender = createFileAppenderWithFilePattern(pattern);

   BUILDER.add(appender);

   logger.add(BUILDER.newAppenderRef("RollingFileAppender"));

   BUILDER.add(logger);

   Configurator.initialize(BUILDER.build());
}

public AppenderComponentBuilder createFileAppenderWithFilePattern(final String pattern) {
   final AppenderComponentBuilder acb = BUILDER.newAppender("RollingFileAppender", "RollingFile");
   acb.addAttribute("fileName",    pattern); 
   acb.addAttribute("filePattern", pattern);
   acb.addComponent(createPatternLayout());
   acb.addComponent(createTimeBasedTriggeringPolicy());

   return acb;
}

public LayoutComponentBuilder createPatternLayout() {
   final LayoutComponentBuilder lcb = BUILDER.newLayout("PatternLayout");
   lcb.addAttribute("pattern", "%d{yyyy-MM-dd HH:mm:ss.SSS}{GMT}Z %m");

   return lcb;
}

public ComponentBuilder createTimeBasedTriggeringPolicy() {
   final ComponentBuilder policies = BUILDER.newComponent("Policies");
   final ComponentBuilder policy   = BUILDER.newComponent("TimeBasedTriggeringPolicy");

   policies.addComponent(policy);

   return policies;  
}

问题是，这段代码完全没有改变任何东西。配置中未添加任何追加器和记录器。以编程方式创建的“文件记录器”不可用

在执行上述代码后，我使用此代码打印记录器和附加器

private void printLog4jConfig() {
   final LoggerContext context = (LoggerContext) LogManager.getContext(false);
   final Configuration config  = context.getConfiguration();


   // Print appenders
   for(Appender app : config.getAppenders().values()) {
      System.out.println(app.getName());
   }

   // Print Loggers and their Appenders
   for(LoggerConfig lc : config.getLoggers().values()) {
      System.out.println(lc);

      for(Appender app : lc.getAppenders().values()) {
         System.out.println("   " + app);
      }
   }
}

输出：

Appenders
-------------
STDOUT


Loggers
-------------
root
   STDOUT
Console
   STDOUT

我的问题：

我的代码怎么了？为什么我的Appender和Logger没有被添加？为什么配置没有被刷新/更新

如何在运行时向log4j2配置添加RollingFileAppender和logger