java - 自定义ConfigurationFactory结合log4j2中的配置文件

Question

我正在尝试 Initialize Log4j by Combining Configuration File with Programmatic Configuration .

我遵循了手册(尽管它的语法不太正确而且已经过时)，导致了以下类:

自定义配置工厂.java:

package factory;

import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.core.config.ConfigurationFactory;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.Order;
import org.apache.logging.log4j.core.config.plugins.Plugin;

import java.net.URI;

@Plugin(name = "CustomConfigurationFactory", category = ConfigurationFactory.CATEGORY)
@Order(1)
public class CustomConfigurationFactory extends ConfigurationFactory {

    /**
     * Valid file extensions for XML files.
     */
    private static final String[] SUFFIXES = new String[]{".xml", "*"};

    /**
     * Return the Configuration.
     *
     * @param source The InputSource.
     * @return The Configuration.
     */
    public Configuration getConfiguration(LoggerContext context, ConfigurationSource source) {

        return new CustomConfiguration(context, source);

    }

    /**
     * Returns the file suffixes for XML files.
     * @return An array of File extensions.
     */
    public String[] getSupportedTypes() {

        return SUFFIXES;

    }

}

自定义配置.java:

package factory;

import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.core.Appender;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.config.ConfigurationSource;
import org.apache.logging.log4j.core.config.LoggerConfig;
import org.apache.logging.log4j.core.config.xml.XmlConfiguration;

import java.util.Map;

public class CustomConfiguration extends XmlConfiguration {

    CustomConfiguration(LoggerContext context, ConfigurationSource configSource) {

        super(context, configSource);

    }

    @Override
    protected void doConfigure() {

        super.doConfigure();

        final LoggerConfig rootLogger = getRootLogger();

        final Map<String, Appender> appenderMap = rootLogger.getAppenders();

        if (MainClass.DEBUG) {

            rootLogger.addAppender(appenderMap.get("Console"), Level.ALL, null);

        } else {

            rootLogger.addAppender(appenderMap.get("Mail"), Level.ERROR, null);

        }

    }
}

现在，在运行它并调用 ConfigurationFactory.setConfigurationFactory(new CustomConfigurationFactory()) 之前调用 Logging API 时，我会以

的形式将输出输出到控制台

ERROR StatusLogger Reconfiguration failed: No configuration found for 'someNumbersAndChars' at 'null' in 'null'

调试时，我发现这是在我第一次获取 Logger 时打印的。原因是，如果提供自定义 ConfigurationFactory，ConfigurationFactory.getConfiguration(LoggerContext, String, URI) 的实现由 ConfigurationFactory的私有(private)子类 Factory(默认工厂)将被 ConfigurationFactory 的实现覆盖。

如果 URI 是这样的话，ConfigurationFactory 的实现简单地返回 null，而 ConfigurationFactory.Factory 的实现仍然返回一个有效的配置.

(link to source)

我现在的第一个想法是在我的自定义工厂中覆盖 ConfigurationFactory.getConfiguration() 的这些重载，但必须有另一种方法，对吗？ ;)

Answer 1

我通过调用解决了这个问题

System.setProperty("log4j.configurationFactory", CustomConfigurationFactory.class.getName());

作为替代方法，使用此 JVM 启动参数:
-Dlog4j.configurationFactory=factory.CustomConfigurationFactory

代替

ConfigurationFactory.setConfigurationFactory(new CustomConfigurationFactory());

在第一次访问 LogManager 之前。

-

编辑:您还可以在文件 log4j2.component.properties 中配置此设置。

内容:

log4j.configurationFactory=factory.CustomConfigurationFactory

通过这样做，您可以确保在加载任何记录器类之前应用此设置，并避免类初始化顺序的潜在问题。

如果您在 Log4j2 源代码中查找 org.apache.logging.log4j.util.PropertiesUtil 的用法，您可以找到可以通过这种方式配置的所有设置。

-

在分析/调试问题时，我注意到我的 ConfigurationFactory 已创建，但未用于获取配置。

最后我在docs中找到了这段话，这解释了一切(我们可能没有足够早地调用 setConfigurationFactory):

During initialization, Log4j 2 will search for available ConfigurationFactories and then select the one to use. The selected ConfigurationFactory creates the Configuration that Log4j will use. Here is how Log4j finds the available ConfigurationFactories:

1. A system property named "log4j.configurationFactory" can be set with the name of the ConfigurationFactory to be used.
2. ConfigurationFactory.setConfigurationFactory(ConfigurationFactory) can be called with the instance of the ConfigurationFactory to be used. This must be called before any other calls to Log4j.
3. A ConfigurationFactory implementation can be added to the classpath and configured as a plugin in the "ConfigurationFactory" category. The Order annotation can be used to specify the relative priority when multiple applicable ConfigurationFactories are found.