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📜  log4j-日志记录级别

📅  最后修改于: 2020-11-12 05:51:17             🧑  作者: Mango

org.apache.log4j.Level级别。您还可以通过对Level类进行子类化来定义自定义级别。

Level Description
ALL All levels including custom levels.
DEBUG Designates fine-grained informational events that are most useful to debug an application.
INFO Designates informational messages that highlight the progress of the application at coarse-grained level.
WARN Designates potentially harmful situations.
ERROR Designates error events that might still allow the application to continue running.
FATAL Designates very severe error events that will presumably lead the application to abort.
OFF The highest possible rank and is intended to turn off logging.
TRACE Designates finer-grained informational events than the DEBUG.

级别如何运作?

如果p> = q，则在级别为q的记录器中启用级别为p的日志请求。此规则是log4j的核心。它假定级别是有序的。对于标准级别，我们有ALL

以下示例说明了如何过滤所有DEBUG和INFO消息。该程序使用记录器方法setLevel(Level.X)设置所需的记录级别：

此示例将打印除调试和信息以外的所有消息：

import org.apache.log4j.*;

public class LogClass {
   private static org.apache.log4j.Logger log = Logger.getLogger(LogClass.class);
   
   public static void main(String[] args) {
      log.setLevel(Level.WARN);

      log.trace("Trace Message!");
      log.debug("Debug Message!");
      log.info("Info Message!");
      log.warn("Warn Message!");
      log.error("Error Message!");
      log.fatal("Fatal Message!");
   }
}

编译并运行LogClass程序时，它将生成以下结果-

Warn Message!
Error Message!
Fatal Message!

使用配置文件设置级别

log4j为您提供了基于配置文件的级别设置，该级别设置使您无需更改源代码即可更改调试级别。

以下是一个示例配置文件，该文件将执行与上述示例中使用log.setLevel(Level.WARN)方法执行的任务相同的任务。

# Define the root logger with appender file
log = /usr/home/log4j
log4j.rootLogger = WARN, FILE

# Define the file appender
log4j.appender.FILE=org.apache.log4j.FileAppender
log4j.appender.FILE.File=${log}/log.out

# Define the layout for file appender
log4j.appender.FILE.layout=org.apache.log4j.PatternLayout
log4j.appender.FILE.layout.conversionPattern=%m%n

现在让我们使用下面的程序-

import org.apache.log4j.*;

public class LogClass {

   private static org.apache.log4j.Logger log = Logger.getLogger(LogClass.class);
   
   public static void main(String[] args) {
   
      log.trace("Trace Message!");
      log.debug("Debug Message!");
      log.info("Info Message!");
      log.warn("Warn Message!");
      log.error("Error Message!");
      log.fatal("Fatal Message!");
   }
}

现在编译并运行以上程序，您将在/usr/home/log4j/log.out文件中得到以下结果-

Warn Message!
Error Message!
Fatal Message!