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Java > Open Source Codes > org > jboss > mx > interceptor > AbstractInterceptor


1 /*
2 * JBoss, Home of Professional Open Source
3 * Copyright 2005, JBoss Inc., and individual contributors as indicated
4 * by the @authors tag. See the copyright.txt in the distribution for a
5 * full listing of individual contributors.
6 *
7 * This is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU Lesser General Public License as
9 * published by the Free Software Foundation; either version 2.1 of
10 * the License, or (at your option) any later version.
11 *
12 * This software is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this software; if not, write to the Free
19 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21 */
22 package org.jboss.mx.interceptor;
23
24 import javax.management.MBeanServer JavaDoc;
25 import javax.management.ObjectName JavaDoc;
26
27 import org.jboss.logging.Logger;
28 import org.jboss.mx.server.Invocation;
29
30 /**
31  * Base class for all interceptors. This class provides some default method
32  * implementations for interceptors.
33  *
34  * @see org.jboss.mx.interceptor.Interceptor
35  * @see org.jboss.mx.server.MBeanInvoker
36  *
37  * @author <a HREF="mailto:juha@jboss.org">Juha Lindfors</a>.
38  * @version $Revision: 37459 $
39  */
40 public abstract class AbstractInterceptor
41    implements Interceptor
42 {
43
44    // Attributes ----------------------------------------------------
45
46    /**
47     * Name for this interceptor.
48     */
49    protected String JavaDoc name = "<no name>";
50    
51    /**
52     * Indicates whether this interceptor instance is shared or not.
53     */
54    protected boolean isShared = false;
55    
56    /**
57     * Logger reference for interceptor implementations. This reference is
58     * set by the invoker for non-shared interceptors after construction.
59     * Shared interceptors will should create their own logger instance.
60     */
61    protected Logger log;
62    
63    
64    // Constructors --------------------------------------------------
65
66    /**
67     * Constructs a new intereceptor instance. This interceptor is not shared
68     * in the MBean server.
69     */
70    public AbstractInterceptor()
71    {
72       log = Logger.getLogger(getClass());
73    }
74    
75    /**
76     * Constructs a new interceptor instance with a given name. This interceptor
77     * is not shared in the MBean server.
78     *
79     * @param name name of this interceptor
80     *
81     * @throws IllegalArgumentException if name contains <tt>null</tt> reference
82     */
83    public AbstractInterceptor(String JavaDoc name)
84    {
85       if (name == null || name.equals(""))
86          throw new IllegalArgumentException JavaDoc("null name");
87          
88       this.name = name;
89
90       log = Logger.getLogger(getClass());
91    }
92    
93
94    // Public --------------------------------------------------------
95
96    /**
97     * Sets a name for this interceptor.
98     *
99     * @param name
100     */
101    public void setName(String JavaDoc name)
102    {
103       this.name = name;
104    }
105    
106    
107    // Interceptor implementation ------------------------------------
108
109    /**
110     * The default invoke implementation queries the invocation object for the
111     * next interceptor in the chain. If one exists, it is invoked. Otherwise
112     * the invocation is dispatched to the target object. <p>
113     *
114     * Concrete implementations should override this method to implement
115     * their specific application logic.
116     *
117     * @see org.jboss.mx.server.Invocation
118     * @see org.jboss.mx.server.MBeanInvoker
119     *
120     * @param invocation the invocation object send towards the target
121     * resource by the invoker
122     *
123     * @return return value from the target resource
124     *
125     * @throws InvocationException This exception wraps any exceptions thrown
126     * by either the target method of the resource object, or invocation
127     * interceptors in this interceptor chain. The target exception is
128     * unwrapped at the {@link org.jboss.mx.server.MBeanInvoker} instance.
129     */
130    public Object JavaDoc invoke(Invocation invocation) throws Throwable JavaDoc
131    {
132       Interceptor ic = invocation.nextInterceptor();
133       
134       // if the invocation object does not provide us with more interceptors,
135 // invoke the dispatcher that lands the invocation to its final target
136 // in the resource object
137 if (ic == null)
138          return invocation.dispatch();
139       
140       // see if the next interceptor in the chain is shared
141 if (ic.isShared())
142       {
143          // we require a common interface for all shared interceptors
144 SharedInterceptor shared = (SharedInterceptor)ic;
145          
146          // we invoke shared interceptor it via the MBean server bus, get the
147 // interceptors view to its MBean server
148 MBeanServer JavaDoc server = shared.getMBeanServer();
149          
150          // And the object name the interceptor is registered under
151 ObjectName JavaDoc name = shared.getObjectName();
152          
153          return server.invoke(
154                   name, "invoke",
155                   new Object JavaDoc[] { invocation }, // args
156 new String JavaDoc[] { Invocation.class.getName() } // signature
157 );
158       }
159       
160       // invoke non-shared interceptor directly via Java reference
161 else
162       {
163          return ic.invoke(invocation);
164       }
165    }
166
167    public String JavaDoc getName()
168    {
169       return name;
170    }
171    
172    public boolean isShared()
173    {
174       return isShared;
175    }
176       
177    public void setLogger(Logger log)
178    {
179       this.log = log;
180    }
181    
182    public void init() throws Exception JavaDoc {}
183
184    public void start() {}
185
186    public void stop() throws Exception JavaDoc {}
187
188    public void destroy() {}
189
190    
191    // Object overrides ----------------------------------------------
192
193    /**
194     * Returns a string representation of this interceptor instance.
195     *
196     * @return string representation
197     */
198    public String JavaDoc toString()
199    {
200       String JavaDoc className = getClass().getName();
201       int index = className.lastIndexOf('.');
202       
203       return className.substring((index < 0) ? 0 : index) + "[name=" + name + "]";
204    }
205 }
206
207
208
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