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Java > Open Source Codes > org > logicalcobwebs > logging > impl > Log4jFactory


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57
58 package org.logicalcobwebs.logging.impl;
59
60 import org.apache.log4j.Category;
61 import org.logicalcobwebs.logging.Log;
62 import org.logicalcobwebs.logging.LogConfigurationException;
63 import org.logicalcobwebs.logging.LogFactory;
64
65 import java.util.Enumeration JavaDoc;
66 import java.util.Hashtable JavaDoc;
67 import java.util.Vector JavaDoc;
68
69 /**
70  * <p>Concrete subclass of {@link org.logicalcobwebs.logging.LogFactory} specific to log4j.
71  *
72  * @author Costin Manolache
73  */
74 public final class Log4jFactory extends LogFactory {
75
76     public Log4jFactory () {
77         super ();
78     }
79
80     /**
81      * The configuration attributes for this {@link org.logicalcobwebs.logging.LogFactory}.
82      */
83     private Hashtable JavaDoc attributes = new Hashtable JavaDoc ();
84
85     // previously returned instances, to avoid creation of proxies
86 private Hashtable JavaDoc instances = new Hashtable JavaDoc ();
87
88     // --------------------------------------------------------- Public Methods
89
90     /**
91      * Return the configuration attribute with the specified name (if any),
92      * or <code>null</code> if there is no such attribute.
93      *
94      * @param name Name of the attribute to return
95      */
96     public Object JavaDoc getAttribute (String JavaDoc name) {
97         return (attributes.get (name));
98     }
99
100     /**
101      * Return an array containing the names of all currently defined
102      * configuration attributes. If there are no such attributes, a zero
103      * length array is returned.
104      */
105     public String JavaDoc[] getAttributeNames () {
106         Vector JavaDoc names = new Vector JavaDoc ();
107         Enumeration JavaDoc keys = attributes.keys ();
108         while (keys.hasMoreElements ()) {
109             names.addElement (keys.nextElement ());
110         }
111         String JavaDoc results[] = new String JavaDoc[names.size ()];
112         for (int i = 0; i < results.length; i++) {
113             results[i] = (String JavaDoc) names.elementAt (i);
114         }
115         return (results);
116     }
117
118     /**
119      * Convenience method to derive a name from the specified class and
120      * call <code>getInstance(String)</code> with it.
121      *
122      * @param clazz Class for which a suitable Log name will be derived
123      *
124      * @exception org.logicalcobwebs.logging.LogConfigurationException if a suitable <code>Log</code>
125      * instance cannot be returned
126      */
127     public Log getInstance (Class JavaDoc clazz)
128             throws LogConfigurationException {
129         Log instance = (Log) instances.get (clazz);
130         if (instance != null) {
131             return instance;
132         }
133
134         instance = new Log4JCategoryLog (Category.getInstance (clazz));
135         instances.put (clazz, instance);
136         return instance;
137     }
138
139     public Log getInstance (String JavaDoc name)
140             throws LogConfigurationException {
141         Log instance = (Log) instances.get (name);
142         if (instance != null) {
143             return instance;
144         }
145
146
147         instance = new Log4JCategoryLog (Category.getInstance (name));
148         instances.put (name, instance);
149         return instance;
150     }
151
152     /**
153      * Release any internal references to previously created {@link org.logicalcobwebs.logging.Log}
154      * instances returned by this factory. This is useful environments
155      * like servlet containers, which implement application reloading by
156      * throwing away a ClassLoader. Dangling references to objects in that
157      * class loader would prevent garbage collection.
158      */
159     public void release () {
160
161         instances.clear ();
162
163         // what's the log4j mechanism to cleanup ???
164 }
165
166     /**
167      * Remove any configuration attribute associated with the specified name.
168      * If there is no such attribute, no action is taken.
169      *
170      * @param name Name of the attribute to remove
171      */
172     public void removeAttribute (String JavaDoc name) {
173         attributes.remove (name);
174     }
175
176     /**
177      * Set the configuration attribute with the specified name. Calling
178      * this with a <code>null</code> value is equivalent to calling
179      * <code>removeAttribute(name)</code>.
180      *
181      * @param name Name of the attribute to set
182      * @param value Value of the attribute to set, or <code>null</code>
183      * to remove any setting for this attribute
184      */
185     public void setAttribute (String JavaDoc name, Object JavaDoc value) {
186         if (value == null) {
187             attributes.remove (name);
188         } else {
189             attributes.put (name, value);
190         }
191     }
192
193 }
194
195
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