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在 Java 中初始化和使用 Log4J

发布于 2024-10-11 17:41:40 字数 143 浏览 6 评论 0原文

我需要知道如何在java中初始化和使用Log4j...... 当我尝试使用它时，出现以下错误

log4j:WARN No Appender can be find for logger (Main)。 log4j:WARN 请正确初始化 log4j 系统。

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情域 2024-10-18 17:41:40

您可以将 log4j.properties 放入 src 文件夹中，系统会自动检查 log4j 配置。默认配置可能如下所示。

### Root Logger
log4j.rootLogger=DEBUG, Console

### Console Appender
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d (%t) %-5p %c: %m%n

否则，您可以通过编程方式调用默认配置。

 import com.foo.Bar;

 // Import log4j classes.
 import org.apache.log4j.Logger;
 import org.apache.log4j.BasicConfigurator;

 public class MyApp {

   // Define a static logger variable so that it references the
   // Logger instance named "MyApp".
   static Logger logger = Logger.getLogger(MyApp.class);

   public static void main(String[] args) {

     // Set up a simple configuration that logs on the console.
     BasicConfigurator.configure();

     logger.info("Entering application.");
     Bar bar = new Bar();
     bar.doIt();
     logger.info("Exiting application.");
   }
 }

摘自 Apache log4j 的简短介绍文档。在提出多余的问题之前，您应该先查找类似的问题。

考虑切换到 SLF4J 这使您可以轻松切换日志记录实现。

You could place a log4j.properties into your src folder, this is automatically checked for log4j configuration. A default configuration could look like this.

### Root Logger
log4j.rootLogger=DEBUG, Console

### Console Appender
log4j.appender.Console=org.apache.log4j.ConsoleAppender
log4j.appender.Console.layout=org.apache.log4j.PatternLayout
log4j.appender.Console.layout.ConversionPattern=%d (%t) %-5p %c: %m%n

Otherwise you could call the default configuration programmatically.

 import com.foo.Bar;

 // Import log4j classes.
 import org.apache.log4j.Logger;
 import org.apache.log4j.BasicConfigurator;

 public class MyApp {

   // Define a static logger variable so that it references the
   // Logger instance named "MyApp".
   static Logger logger = Logger.getLogger(MyApp.class);

   public static void main(String[] args) {

     // Set up a simple configuration that logs on the console.
     BasicConfigurator.configure();

     logger.info("Entering application.");
     Bar bar = new Bar();
     bar.doIt();
     logger.info("Exiting application.");
   }
 }

Taken from the short introduction document of Apache log4j. You should look for similiar questions before asking them redudant.

Consider to switch to SLF4J which enables you the possibilities to switch the logging implementation easily.

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