slf4j日志文件在哪里保存？ [英] Where does the slf4j log file get saved?

问题描述

我有以下导入：

  import org.slf4j.Logger; 
 import org.slf4j.LoggerFactory; 
  

以及以下实例：

  private static Logger logger = LoggerFactory.getLogger（Test.class）; 
  

以及我的Main方法中的以下内容：

  logger.info（SOME MESSAGE：）; 
  

但是，我无法在任何地方找到输出。我只看到在我的控制台中有：

  21：21：24.235 [main] INFO some_folder.Test  -  SOME MESSAGE ：
  

如何找到日志文件？

请注意，以下内容位于我的构建路径中：

slf4j-api-1.7.5.jar

slf4j-log4j12-1.6.4.jar

<我读了类似问题的答案，但没有人真正说明如何解决这个问题。

解决方案

slf4j只是一个API。您应该有一个具体的实现（例如log4j）。这个具体实现有一个配置文件，告诉你存储日志的位置。

当slf4j使用记录器捕获日志消息时，会将其提供给appender，该appender决定如何处理消息。默认情况下，ConsoleAppender在控制台中显示消息。

默认配置文件为：

 <？xml version =1.0encoding =UTF-8？> 
<配置状态=警告> 
 
< Appenders> 
<！ - 默认情况下=>控制台 - > 
< Console name =Consoletarget =SYSTEM_OUT> 
< PatternLayout pattern =％d {HH：mm：ss.SSS} [％t]％-5level％logger {36}  - ％msg％n/> 
< / Console> 
< / Appenders> 
 
< Loggers> 
< Root level =error> 
< AppenderRef ref =控制台/> 
< / Root> 
< / Loggers> 
< /配置> 
  

如果您在类路径中提供配置文件，那么您的具体实现（在您的情况下，log4j） ）会找到并使用它。请参阅 Log4J文档。

文件追加器的示例：

 < Appenders> 
<文件名=文件fileName =$ {filename}> 
< PatternLayout> 
< pattern>％d％p％C {1。} [％t]％m％n< / pattern> 
< / PatternLayout> 
< / File> 
 
 ... 
< / Appenders> 
  

文件追加器的完整示例：

 <？xml version =1.0encoding =UTF-8？> 
<配置状态=警告> 
 
< Appenders> 
<文件名=文件fileName =$ {filename}> 
< PatternLayout> 
< pattern>％d％p％C {1。} [％t]％m％n< / pattern> 
< / PatternLayout> 
< / File> 
< / Appenders> 
 
< Loggers> 
< Root level =error> 
< AppenderRef ref =File/> 
< / Root> 
< / Loggers> 
 
< / Configuration> 
  

I have the followed imports:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

and the following instantiation:

private static Logger logger = LoggerFactory.getLogger(Test.class);

and the following in my Main method:

logger.info("SOME MESSAGE: ");

However, I'm not able to find the output anywhere. All I see is that in my console there is:

21:21:24.235 [main] INFO  some_folder.Test - SOME MESSAGE: 

How do I locate the log file?

Note that the following are on my build path:

slf4j-api-1.7.5.jar

slf4j-log4j12-1.6.4.jar

I read the answer to similar questions but nobody actually says how to fix the problem.

解决方案

slf4j is only an API. You should have a concrete implementation (for example log4j). This concrete implementation has a config file which tells you where to store the logs.

When slf4j catches a log messages with a logger, it is given to an appender which decides what to do with the message. By default, the ConsoleAppender displays the message in the console.

The default configuration file is :

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">

  <Appenders>
    <!-- By default => console -->
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </Appenders>

  <Loggers>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
  </Loggers>
</Configuration>

If you put a configuration file available in the classpath, then your concrete implementation (in your case, log4j) will find and use it. See Log4J documentation.

Example of file appender :

<Appenders>
<File name="File" fileName="${filename}">
  <PatternLayout>
    <pattern>%d %p %C{1.} [%t] %m%n</pattern>
  </PatternLayout>
</File>

...
</Appenders>

Complete example with a file appender :

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">

  <Appenders>
    <File name="File" fileName="${filename}">
      <PatternLayout>
        <pattern>%d %p %C{1.} [%t] %m%n</pattern>
      </PatternLayout>
    </File>
  </Appenders>

  <Loggers>
    <Root level="error">
      <AppenderRef ref="File"/>
    </Root>
  </Loggers>

</Configuration>

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