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 package org.apache.log4j.spi;
18
19 /**
20 * @since 0.9.0
21 */
22 public abstract class Filter {
23
24 /**
25 * The log event must be dropped immediately without consulting
26 * with the remaining filters, if any, in the chain.
27 */
28 public static final int DENY = -1;
29
30 /**
31 * This filter is neutral with respect to the log event. The
32 * remaining filters, if any, should be consulted for a final decision.
33 */
34 public static final int NEUTRAL = 0;
35
36 /**
37 * The log event must be logged immediately without consulting with
38 * the remaining filters, if any, in the chain.
39 */
40 public static final int ACCEPT = 1;
41
42 /**
43 * Points to the next filter in the filter chain.
44 *
45 * @deprecated As of 1.2.12, use {@link #getNext} and {@link #setNext} instead
46 */
47 @Deprecated
48 public Filter next;
49
50 /**
51 * Usually filters options become active when set. We provide a
52 * default do-nothing implementation for convenience.
53 */
54 public void activateOptions() {
55 }
56
57
58 /**
59 * <p>If the decision is <code>DENY</code>, then the event will be
60 * dropped. If the decision is <code>NEUTRAL</code>, then the next
61 * filter, if any, will be invoked. If the decision is ACCEPT then
62 * the event will be logged without consulting with other filters in
63 * the chain.
64 *
65 * @param event The LoggingEvent to decide upon.
66 * @return decision The decision of the filter.
67 */
68 public abstract int decide(LoggingEvent event);
69
70 /**
71 * Set the next filter pointer.
72 * @param next The next Filter.
73 */
74 public void setNext(final Filter next) {
75 this.next = next;
76 }
77
78 /**
79 * Return the pointer to the next filter.
80 * @return The next Filter.
81 */
82 public Filter getNext() {
83 return next;
84 }
85
86 }