rootlogger.java

apache的log4j源码

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.spi;

import org.apache.log4j.*;
import org.apache.log4j.helpers.LogLog;


// Contibutors: Mathias Bogaert

/**
   RootLogger sits at the top of the logger hierachy. It is a
   regular logger except that it provides several guarantees.

   <p>First, it cannot be assigned a <code>null</code>
   level. Second, since root logger cannot have a parent, the
   {@link #getChainedLevel} method always returns the value of the
   level field without walking the hierarchy.

   @author Ceki G&uuml;lc&uuml;

 */
public final class RootLogger extends Logger {
  /**
     The root logger names itself as "root". However, the root
     logger cannot be retrieved by name.
  */
  public RootLogger(Level level) {
    super("root");
    setLevel(level);
  }

  /**
     Return the assigned level value without walking the logger
     hierarchy.
  */
  public final Level getChainedLevel() {
    return level;
  }

  /**
     Setting a null value to the level of the root logger may have catastrophic
     results. We prevent this here.

     @since 0.8.3 */
  public final void setLevel(Level level) {
    if (level == null) {
      LogLog.error(
        "You have tried to set a null level to root.", new Throwable());
    } else {
      this.level = level;
    }
  }

}