1 /*
2 * #%L
3 * settings4j
4 * ===============================================================
5 * Copyright (C) 2008 - 2015 Brabenetz Harald, Austria
6 * ===============================================================
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 * #L%
19 */
20 package org.settings4j.helper.web;
21
22 import java.net.MalformedURLException;
23 import java.net.URL;
24 import java.util.Locale;
25
26 import javax.servlet.ServletContext;
27
28 import org.apache.log4j.PropertyConfigurator;
29 import org.apache.log4j.helpers.Loader;
30 import org.apache.log4j.xml.DOMConfigurator;
31 import org.settings4j.Settings4j;
32
33
34 /**
35 * With this Implementation you can define a Key in your web.xml (init-parameter "settings4jLog4jConfigurationKey") with that you can configure your Path to
36 * your log4j.xml.
37 * <p>
38 * Each WebApplication in you Servlet Container can have its own key. And so you can configure for each webApplication a separated log4j.xml.
39 * </p>
40 * <p>
41 * See Example {@link Log4jConfigurationLoaderListener}.
42 * </p>
43 *
44 * @author brabenetz
45 */
46 public class Log4jConfigurationLoader {
47
48 /**
49 * Key for log4j configuration.
50 */
51 public static final String LOG4J_CONFIG_SETTINGS4JKEY = "settings4jLog4jConfigurationKey";
52
53 private ServletContext servletContext;
54
55 /**
56 * If the InitParameter "Settings4jLog4jConfigurationKey" exists in the given {@link ServletContext}, then Log4j
57 * will be configured with it.
58 *
59 * @param servCxt The ServletContext where the InitParameters are configured.
60 */
61 public void initLog4jConfiguration(final ServletContext servCxt) {
62 this.servletContext = servCxt;
63
64 // be sure that the DefaultPropertiesLoader is initialized:
65 createDefaultPropertiesLoader().initDefaultProperties(this.servletContext);
66
67 final String log4jConfigSettings4jKey = this.servletContext.getInitParameter(LOG4J_CONFIG_SETTINGS4JKEY);
68 if (log4jConfigSettings4jKey == null) {
69 log("Log4j not initialized: context parameter not set [name=" + LOG4J_CONFIG_SETTINGS4JKEY + "]");
70 return;
71 }
72 final String configLocation = Settings4j.getString(log4jConfigSettings4jKey);
73 if (configLocation == null) {
74 log("Log4j not initialized: configLocation not set");
75 } else {
76 try {
77 this.initLogging(configLocation);
78 log("Log4j initialized [configurationPath=" + configLocation + "]");
79 } catch (final Throwable e) {
80 log("Log4j not initialized [configurationPath=" + configLocation + "]", e);
81 }
82 }
83 }
84
85 /**
86 * @param configLocation location.
87 */
88 protected void initLogging(final String configLocation) {
89 log("initLogging [" + configLocation + "].");
90 URL url = null;
91 try {
92 url = new URL(configLocation);
93 log("found url: " + url);
94 } catch (@SuppressWarnings("unused") final MalformedURLException ex) {
95 // so, resource is not a URL:
96 // attempt to get the resource from the class path
97 log("attempt to get the resource from the class path.");
98 url = Loader.getResource(configLocation);
99 }
100 if (url != null) {
101 log("Using URL [" + url + "] for automatic log4j configuration.");
102
103 if (configLocation.toLowerCase(Locale.ENGLISH).endsWith(".xml")) {
104 DOMConfigurator.configure(url);
105 } else {
106 PropertyConfigurator.configure(url);
107 }
108
109 } else {
110 log("Could not find resource: [" + configLocation + "].");
111 }
112 }
113
114
115 /**
116 * Writes an explanatory message and a stack trace for a given <code>Throwable</code> exception to the servlet log
117 * file. The name and type of the servlet log file is specific to the servlet container, usually an event log.
118 *
119 * @param message a <code>String</code> that describes the error or exception
120 * @param throwable the <code>Throwable</code> error or exception
121 */
122 public void log(final String message, final Throwable throwable) {
123 this.servletContext.log(message, throwable);
124 }
125
126 /**
127 * Writes the specified message to a servlet log file, usually an event log. The name and type of the servlet log
128 * file is specific to the servlet container.
129 *
130 * @param msg a <code>String</code> specifying the message to be written to the log file
131 */
132 public void log(final String msg) {
133 this.servletContext.log(msg);
134 }
135
136 /**
137 * Create the DefaultPropertiesLoader to use. Can be overridden in subclasses.
138 *
139 * @return the new DefaultPropertiesLoader
140 */
141 protected DefaultPropertiesLoader createDefaultPropertiesLoader() {
142 return new DefaultPropertiesLoader();
143 }
144
145 }