您需要多久设置一次 log4j2 的配置文件？

Question

我在一个包中有多个 classes，在我的项目中有多个包。对于那些继承的文件，在父 class 中是

 { // File location for log4j2.xml
    System.setProperty("log4j.configurationFile",
        "file:\\" + System.getProperty("user.dir") + "\Properties\log4j2.xml");
}

然而，我看到了 ERROR StatusLogger No log4j2 configuration file found. Using default configuration: logging only errors to the console. Set system property 'log4j2.debug' to show Log4j2 internal initialization logging.

所以，显然，一次是不够的。

那么我需要设置 log4j.configurationFile 的系统属性的一般规则是什么？

每个包裹一次？
每 class 一次?
每个parent/baseclass，不管包?
还是别的？

多个 class 和包的最佳做法是什么？

Answer 1

Log4j 2 在初始化时自行配置，即每当在 JVM 实例中首次创建 Logger 实例时，大约......应用程序中声明 Logger 实例的第一个 class 会导致 Log4j 2 初始化本身。所以，这个问题的答案...

How often do you need to set the configuration file for log4j2?

...是一次。

您的 OP 中报告的问题：No log4j2 configuration file found. Using default configuration 是由于 Log4j 无法找到您试图指向的配置文件造成的。此问题不是引起的 'setting the configuration file' 不够频繁。

根据the docs Log4j 将按如下方式查找其配置源：

Log4j will inspect the "log4j.configurationFile" system property and, if set, will attempt to load the configuration using the ConfigurationFactory that matches the file extension.

If no system property is set the properties ConfigurationFactory will look for log4j2-test.properties in the classpath.

If no such file is found the YAML ConfigurationFactory will look for log4j2-test.yaml or log4j2-test.yml in the classpath.

If no such file is found the JSON ConfigurationFactory will look for log4j2-test.json or log4j2-test.jsn in the classpath.

If no such file is found the XML ConfigurationFactory will look for log4j2-test.xml in the classpath.

If a test file cannot be located the properties ConfigurationFactory will look for log4j2.properties on the classpath.

If a properties file cannot be located the YAML ConfigurationFactory will look for log4j2.yaml or log4j2.yml on the classpath.

If a YAML file cannot be located the JSON ConfigurationFactory will look for log4j2.json or log4j2.jsn on the classpath.

If a JSON file cannot be located the XML ConfigurationFactory will try to locate log4j2.xml on the classpath.

If no configuration file could be located the DefaultConfiguration will be used. This will cause logging output to go to the console.

如果您尝试设置 log4j.configurationFile 成功，那么选项 1 将被启用，但该尝试不成功，我们知道这一点，因为您引用的错误消息告诉我们 Log4j 正在失败选项 10.

我建议运行您的应用程序带有 -Dlog4j.configurationFile=/path/to/log4j2.xml 或确保 log4j2.xml 在您的应用程序的 class路径。用 System.setProperty(...) 调用乱丢代码的想法感觉像是一种反模式，并且可能非常脆弱，因为在 System.setProperty(...) 调用之前实例化的任何静态记录器将导致 Log4j 在知道您的配置文件位置之前自行初始化。

您需要多久设置一次 log4j2 的配置文件？

How often do you need to set the configuration file for log4j2?

java

log4j2

configuration-files