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.logging.log4j.core.appender;
18
19 import java.io.Serializable;
20
21 import org.apache.logging.log4j.core.Appender;
22 import org.apache.logging.log4j.core.ErrorHandler;
23 import org.apache.logging.log4j.core.Filter;
24 import org.apache.logging.log4j.core.Layout;
25 import org.apache.logging.log4j.core.LogEvent;
26 import org.apache.logging.log4j.core.filter.AbstractFilterable;
27 import org.apache.logging.log4j.core.util.Integers;
28
29 /**
30 * Abstract base class for Appenders. Although Appenders do not have to extend this class, doing so
31 * will simplify their implementation.
32 */
33 public abstract class AbstractAppender extends AbstractFilterable
34 implements Appender {
35
36 private static final long serialVersionUID = 1L;
37
38 private final boolean ignoreExceptions;
39
40 private ErrorHandler handler = new DefaultErrorHandler(this);
41
42 private final Layout<? extends Serializable> layout;
43
44 private final String name;
45
46 public static int parseInt(final String s, final int defaultValue) {
47 try {
48 return Integers.parseInt(s, defaultValue);
49 } catch (final NumberFormatException e) {
50 LOGGER.error("Could not parse \"{}\" as an integer, using default value {}: {}", s, defaultValue, e);
51 return defaultValue;
52 }
53 }
54
55 /**
56 * Constructor that defaults to suppressing exceptions.
57 * @param name The Appender name.
58 * @param filter The Filter to associate with the Appender.
59 * @param layout The layout to use to format the event.
60 */
61 protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout) {
62 this(name, filter, layout, true);
63 }
64
65 /**
66 * Constructor.
67 * @param name The Appender name.
68 * @param filter The Filter to associate with the Appender.
69 * @param layout The layout to use to format the event.
70 * @param ignoreExceptions If true, exceptions will be logged and suppressed. If false errors will be
71 * logged and then passed to the application.
72 */
73 protected AbstractAppender(final String name, final Filter filter, final Layout<? extends Serializable> layout,
74 final boolean ignoreExceptions) {
75 super(filter);
76 this.name = name;
77 this.layout = layout;
78 this.ignoreExceptions = ignoreExceptions;
79 }
80
81 /**
82 * Handle an error with a message using the {@link ErrorHandler} configured for this Appender.
83 * @param msg The message.
84 */
85 public void error(final String msg) {
86 handler.error(msg);
87 }
88
89 /**
90 * Handle an error with a message, exception, and a logging event, using the {@link ErrorHandler} configured for
91 * this Appender.
92 * @param msg The message.
93 * @param event The LogEvent.
94 * @param t The Throwable.
95 */
96 public void error(final String msg, final LogEvent event, final Throwable t) {
97 handler.error(msg, event, t);
98 }
99
100 /**
101 * Handle an error with a message and an exception using the {@link ErrorHandler} configured for this Appender.
102 * @param msg The message.
103 * @param t The Throwable.
104 */
105 public void error(final String msg, final Throwable t) {
106 handler.error(msg, t);
107 }
108
109 /**
110 * Returns the ErrorHandler, if any.
111 * @return The ErrorHandler.
112 */
113 @Override
114 public ErrorHandler getHandler() {
115 return handler;
116 }
117
118 /**
119 * Returns the Layout for the appender.
120 * @return The Layout used to format the event.
121 */
122 @Override
123 public Layout<? extends Serializable> getLayout() {
124 return layout;
125 }
126
127 /**
128 * Returns the name of the Appender.
129 * @return The name of the Appender.
130 */
131 @Override
132 public String getName() {
133 return name;
134 }
135
136 /**
137 * Some appenders need to propagate exceptions back to the application. When {@code ignoreExceptions} is
138 * {@code false} the AppenderControl will allow the exception to percolate.
139 *
140 * @return {@code true} if exceptions will be logged but now thrown, {@code false} otherwise.
141 */
142 @Override
143 public boolean ignoreExceptions() {
144 return ignoreExceptions;
145 }
146
147 /**
148 * The handler must be set before the appender is started.
149 * @param handler The ErrorHandler to use.
150 */
151 @Override
152 public void setHandler(final ErrorHandler handler) {
153 if (handler == null) {
154 LOGGER.error("The handler cannot be set to null");
155 }
156 if (isStarted()) {
157 LOGGER.error("The handler cannot be changed once the appender is started");
158 return;
159 }
160 this.handler = handler;
161 }
162
163 @Override
164 public String toString() {
165 return name;
166 }
167
168 }