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 * Points to the next filter in the filter chain. 26 * 27 * @deprecated As of 1.2.12, use {@link #getNext} and {@link #setNext} instead 28 */ 29 public Filter next; 30 31 /** 32 * The log event must be dropped immediately without consulting 33 * with the remaining filters, if any, in the chain. 34 */ 35 public static final int DENY = -1; 36 37 /** 38 * This filter is neutral with respect to the log event. The 39 * remaining filters, if any, should be consulted for a final decision. 40 */ 41 public static final int NEUTRAL = 0; 42 43 /** 44 * The log event must be logged immediately without consulting with 45 * the remaining filters, if any, in the chain. 46 */ 47 public static final int ACCEPT = 1; 48 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 abstract public int decide(LoggingEvent event); 69 70 /** 71 * Set the next filter pointer. 72 */ 73 public void setNext(Filter next) { 74 this.next = next; 75 } 76 77 /** 78 * Return the pointer to the next filter; 79 */ 80 public Filter getNext() { 81 return next; 82 } 83 84 }