SLF4J-如何知道要使用哪种日志类型 [英] SLF4J - how does it know which log type to use

问题描述

SLF4J是包装器/门面类，因此您可以使用许多不同的日志类型，例如logback，log4j等.假设我要同时使用logback和log4j，甚至要同时使用java.util.logging之类的第三个.当我写这样的日志时:

SLF4J is a wrapper/facade class so you can use many different log types, such as logback, log4j , etc. Let's say i want to use both logback and log4j and even a third like java.util.logging. when i write a log like this:

    public class HelloWorld {
  public static void main(String[] args) {
    Logger logger = LoggerFactory.getLogger(HelloWorld.class);
    logger.info("Hello World");
  }
}

我怎么知道它使用哪个日志框架?假设我希望它使用logback进行此调用，我怎么知道它不使用其他框架?

How do i know which logging framework its using ? Let's say i want it to use logback for this call, how do i know its not using another framework ?

推荐答案

如您所知，SLF4J只是一个接口，需要一个实现.基本上，SLF4J会调用:

As you understood, SLF4J is only an interface and needs an implementation. Basically, SLF4J does a call to :

ClassLoader.getSystemResources("org/slf4j/impl/StaticLoggerBinder.class");

编辑:现在，此信息有些过时了.如今，SLF4J似乎使用java.util.ServiceLoader加载org.slf4j.spi.SLF4JServiceProvider，但是逻辑保持不变.

EDIT : now, this information is a bit outdated. It seems that nowadays, SLF4J uses java.util.ServiceLoader to load a org.slf4j.spi.SLF4JServiceProvider but the logic stays the same.

这意味着您的类路径必须包含具有此完全限定名称的此类.

It means that you classpath must contain such a class with this fully qualified name.

每个与slf4j兼容的日志记录框架都定义了此类.

Every logging framework that is compatible with slf4j defines such a class.

• 如果深入研究logback的代码，则会发现一个名为org.slf4j.impl.StaticLoggerBinder的类，该类将重定向到logback的实现
• 如果深入研究log4j的代码，则没有这样的类，但是在log4j和slf4j之间有一个绑定框架，称为slf4j-log4j，该框架还定义了一个名为org.slf4j.impl.StaticLoggerBinder的类，但该类重定向到log4j的实现.

• If you dig into the code of logback, you will find a class named org.slf4j.impl.StaticLoggerBinder which redirects to logback's implementation
• If you dig into the code of log4j, there is not such class but there is a binding framework between log4j and slf4j which is called slf4j-log4j which also define a class named org.slf4j.impl.StaticLoggerBinder but which redirects to log4j's implementation.

因此，如果您希望slf4j使用特定的框架，只需将准确的jar放在类路径中，以便找到org.slf4j.impl.StaticLoggerBinder的相应实现.

So if you want slf4j to use a particular framework, just place the accurate jar in the classpath so that the corresponding implementation of org.slf4j.impl.StaticLoggerBinder is found.

这是全局(来源: http://www.slf4j.org/manual.html ):

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