176 [main] INFO org.foo.Bar - Located nearest gas station.

# %c 輸出日誌訊息所屬的類別的全名
# %d 輸出日誌時間點的日期或時間，指定格式的方式：%d{yyy-MM-dd HH:mm:ss }。
# %l 輸出日誌事件的發生位置，即輸出日誌訊息的語句處於它所在的類別的第幾行。
# %m 輸出訊息，如log(message)中的message。
# %n 輸出一個列尾符號。
# %p 輸出優先階層，即DEBUG，INFO，WARN，ERROR，FATAL。如果是調用debug()輸出的，則為DEBUG，依此類推。
# %r 輸出自應用啟動到輸出該日誌訊息所耗費的毫秒數。
# %t 輸出產生該日誌事件的線程名。
# %r 輸出自應用啟動到輸出該日誌訊息所耗費的毫秒數。
# %f 輸出日誌訊息所屬的類別的類別名。

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">

<!-- ============================================================ -->
<!--  Log4j Configuration -->
<!-- ============================================================ -->

<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/" debug="false">

   <!-- ======================== -->
   <!-- Preserve messages in a local file -->
   <!-- ======================== -->

   <!-- A time/date based rolling appender 定義 log message 輸出FILE檔案 -->
   <appender name="FILE" class="org.jboss.logging.appender.DailyRollingFileAppender">
      <errorHandler class="org.jboss.logging.util.OnlyOnceErrorHandler"/>
      <param name="File" value="${jboss.server.home.dir}/log/server.log"/>
      <param name="Append" value="false"/>

      <!-- Rollover at midnight each day -->
      <param name="DatePattern" value="'.'yyyy-MM-dd"/>

      <!-- 定義 log message 的格式 -->
      <layout class="org.apache.log4j.PatternLayout">
         <!-- The default pattern: Date Priority [Category] Message\n -->
         <param name="ConversionPattern" value="%d %-5p [%c] %m%n"/>

      </layout>
   </appender>


   <!-- ===================================================== -->
   <!-- Append messages to the console 定義 log message 輸出 Console -->
   <!-- ===================================================== -->

   <appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">
      <errorHandler class="org.jboss.logging.util.OnlyOnceErrorHandler"/>
      <param name="Target" value="System.out"/>
      <param name="Threshold" value="INFO"/>

      <!-- 定義 log message 的格式 -->
      <layout class="org.apache.log4j.PatternLayout">
         <!-- The default pattern: Date Priority [Category] Message\n -->
         <param name="ConversionPattern" value="%d{ABSOLUTE} %-5p [%c{1}] %m%n"/>
      </layout>
   </appender>


   <!-- ========================================= -->
   <!-- Limit categories 對 class: com.demos 作偵錯觀察 -->
   <!-- ========================================= -->
   <category name="com.demos">
      <priority value="DEBUG"/>
   </category>

   <!-- ============================ -->
   <!-- Setup the Root category 設定 log 要在那裡產生 -->
   <!-- ============================ -->

   <root>
      <appender-ref ref="CONSOLE"/>
      <appender-ref ref="FILE"/>
   </root>

</log4j:configuration>

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">

   <!-- ===================================================== -->
   <!-- Append messages to the console 定義 log message 輸出至 Console 及 log 內容格式 -->
   <!-- ===================================================== -->
    <appender name="default" class="org.apache.log4j.ConsoleAppender">
        <param name="target" value="System.out" />
        <layout class="org.apache.log4j.PatternLayout">
            <param name="ConversionPattern"
                value="[%p] %d{dd MMM hh:mm:ss.SSS aa} %t [%C-%M]%n%m%n%n" />
        </layout>
    </appender>

    <!-- 設定要偵錯的 calss: com.demos 及 log 要輸出到那一個裝置-->
    <logger name="com.demos">
        <level value="debug" />
        <appender-ref ref="default" />
    </logger>

</log4j:configuration>

package com.demos;

import javax.servlet.http.HttpServletRequest;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionMapping;
import org.apache.log4j.Logger;

public class LookupFormF extends ActionForm{

    static Logger loger = Logger.getLogger(LookupFormF.class.getName());
    private String symbol = null;

    public String getSymbol() {
        return (symbol);
    }

    public void setSymbol(String symbol) {
        this.symbol = symbol;
        loger.debug(symbol);
    }
}

16:54:23,733 INFO  [STDOUT] [DEBUG] 24 十月 04:54:23.733 下午 http-0.0.0.0-8043-
1 [com.demos.LookupFormF-setSymbol]
polinwei

176 [main] INFO  org.foo.Bar - Located nearest gas station.

    %c 輸出日誌訊息所屬的類別的全名
    %d 輸出日誌時間點的日期或時間，指定格式的方式：%d{yyy-MM-dd HH:mm:ss }。
    %l 輸出日誌事件的發生位置，即輸出日誌訊息的語句處於它所在的類別的第幾行。
    %m 輸出代碼中指定的訊息，如log(message)中的message。
    %n 輸出一個列尾符號。
    %p 輸出優先階層，即DEBUG，INFO，WARN，ERROR，FATAL。如果是調用debug()輸出的，則為DEBUG，依此類推。-5p 代表將此字串填滿至 5 個字元,以空白補不足處。
    %r 輸出自應用啟動到輸出該日誌訊息所耗費的毫秒數。
    %t 輸出產生該日誌事件的線程名。
    %f 輸出日誌訊息所屬的類別的類別名。

package yc.usingLog4j;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Logger;

public class UsingLog4j {
     private static Logger logger = Logger.getLogger(UsingLog4j.class);

     public static void main(String[] args) {
     BasicConfigurator.configure();

     logger.info("This is an info message.");
     logger.debug("This is a debug message.");
 }
}

#定義 Root Logger 的等級為 INFO,且為其指定一個 appender 名為 rootAppender.
log4j.rootLogger=info, rootAppender

#指定 rootAppender 的類型.
log4j.appender.rootAppender=org.apache.log4j.ConsoleAppender

#指定 rootAppender 的 Layout.
log4j.appender.rootAppender.layout=org.apache.log4j.PatternLayout

#指定 rootAppender Layout 的輸出格式.
log4j.appender.rootAppender.layout.ConversionPattern=%d [%t] %-5p %c - %m%n

#設定特定名稱的 Logger.
log4j.logger.yc.usingLog4j.UsingLog4jA=INFO, log4jaAppender
log4j.appender.log4jaAppender=org.apache.log4j.RollingFileAppender
log4j.appender.log4jaAppender.File=d:/tmp/usinglog4j.log
log4j.appender.log4jaAppender.MaxFileSize=100KB
log4j.appender.log4jaAppender.MaxBackupIndex=10
log4j.appender.log4jaAppender.layout=org.apache.log4j.PatternLayout
log4j.appender.log4jaAppender.layout.ConversionPattern=%c - %m%n

package yc.usingLog4j;

import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;

public class UsingLog4j {
  private static Logger logger = Logger.getLogger(UsingLog4j.class);

  public static void main(String[] args) {
      BasicConfigurator.configure();

      /* 改變 Root Logger 的等級為 INFO */
      //Logger.getRootLogger().setLevel(Level.INFO);

      /* 鴨子類別庫的 client 只做 INFO 等級的 log;類別庫裡才使用 DEBUG 等級的 log. */
      logger.info("Create a Redhead Duck.");
      RedheadDuck rhd = new RedheadDuck(new FlyWithWings(), new Quack());
      logger.info("Play with the duck.");
      rhd.display();
      rhd.performFly();
      rhd.performQuack();

      logger.info("Create a RubberDuck.");
      RubberDuck rbd = new RubberDuck(new FlyWithRocket(), new Squeak());
      logger.info("Play with the duck.");
      rbd.display();
      rbd.performFly();
      rbd.performQuack();
      }
  }

  interface FlyBehavior {
      public void fly();
  }

  class FlyWithWings implements FlyBehavior {
      private static Logger logger = Logger.getLogger(FlyWithWings.class);

      public void fly() {
      logger.debug("Fly with wings...");
  }
}

class FlyWithRocket implements FlyBehavior {
  private static Logger logger = Logger.getLogger(FlyWithRocket.class);

  public void fly() {
      logger.debug("Fly with a rocket...");
  }
}

interface QuackBehavior {
  public void quack();
}

class Quack implements QuackBehavior {
  private static Logger logger = Logger.getLogger(Quack.class);

  public void quack() {
      logger.debug("Quack...");
  }
}

class Squeak implements QuackBehavior {
  private static Logger logger = Logger.getLogger(Squeak.class);

  public void quack() {
      logger.debug("Squeak...");
  }
}

abstract class Duck {
  private FlyBehavior flyBehavior;

  private QuackBehavior quackBehavior;

  public Duck(FlyBehavior flyBehavior, QuackBehavior quackBehavior) {
      this.flyBehavior = flyBehavior;
      this.quackBehavior = quackBehavior;
  }

  public void performQuack() {
      this.quackBehavior.quack();
  }

  public void performFly() {
   this.flyBehavior.fly();
  }

  public abstract void display();
}

class RedheadDuck extends Duck {
  private static Logger logger = Logger.getLogger(RedheadDuck.class);

  public RedheadDuck(FlyBehavior flyBehavior, QuackBehavior quackBehavior) {
      super(flyBehavior, quackBehavior);
  }

  @Override
  public void display() {
      logger.debug("A RedheadDuck is showing up...");
  }
}

class RubberDuck extends Duck {
  private static Logger logger = Logger.getLogger(RubberDuck.class);

  public RubberDuck(FlyBehavior flyBehavior, QuackBehavior quackBehavior) {
      super(flyBehavior, quackBehavior);
  }

  @Override
  public void display() {
      logger.debug("A RubberDuck is showing up...");
  }
}

0 [main] INFO yc.usingLog4j.UsingLog4j  - Create a Redhead Duck.
16 [main] INFO yc.usingLog4j.UsingLog4j  - Play with the duck.
16 [main] INFO yc.usingLog4j.UsingLog4j  - Create a RubberDuck.
16 [main] INFO yc.usingLog4j.UsingLog4j  - Play with the duck.

0 [main] INFO yc.usingLog4j.UsingLog4j  - Create a Redhead Duck.
109 [main] INFO yc.usingLog4j.UsingLog4j  - Play with the duck.
109 [main] DEBUG yc.usingLog4j.RedheadDuck  - A RedheadDuck is showing up...
109 [main] DEBUG yc.usingLog4j.FlyWithWings  - Fly with wings...
109 [main] DEBUG yc.usingLog4j.Quack  - Quack...
109 [main] INFO yc.usingLog4j.UsingLog4j  - Create a RubberDuck.
125 [main] INFO yc.usingLog4j.UsingLog4j  - Play with the duck.
125 [main] DEBUG yc.usingLog4j.RubberDuck  - A RubberDuck is showing up...
125 [main] DEBUG yc.usingLog4j.FlyWithRocket  - Fly with a rocket...
125 [main] DEBUG yc.usingLog4j.Squeak  - Squeak...