1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.log4j.spi;
19
20 import org.apache.log4j.Level;
21 import org.apache.log4j.Logger;
22 import org.apache.log4j.helpers.LogLog;
23
24
25 // Contibutors: Mathias Bogaert
26
27 /**
28 RootLogger sits at the top of the logger hierachy. It is a
29 regular logger except that it provides several guarantees.
30
31 <p>First, it cannot be assigned a <code>null</code>
32 level. Second, since root logger cannot have a parent, the
33 {@link #getChainedLevel} method always returns the value of the
34 level field without walking the hierarchy.
35
36 @author Ceki Gülcü
37
38 */
39 public final class RootLogger extends Logger {
40 /**
41 The root logger names itself as "root". However, the root
42 logger cannot be retrieved by name.
43 */
44 public RootLogger(Level level) {
45 super("root");
46 setLevel(level);
47 }
48
49 /**
50 Return the assigned level value without walking the logger
51 hierarchy.
52 */
53 public final Level getChainedLevel() {
54 return level;
55 }
56
57 /**
58 Setting a null value to the level of the root logger may have catastrophic
59 results. We prevent this here.
60
61 @since 0.8.3 */
62 public final void setLevel(Level level) {
63 if (level == null) {
64 LogLog.error(
65 "You have tried to set a null level to root.", new Throwable());
66 } else {
67 this.level = level;
68 }
69 }
70
71 }
72