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;
25 import javax.management.ObjectName;
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 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 name)
84 {
85 if (name == null || name.equals(""))
86 throw new IllegalArgumentException("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 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 invoke(Invocation invocation) throws Throwable
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 server = shared.getMBeanServer();
149
150 // And the object name the interceptor is registered under
151 ObjectName name = shared.getObjectName();
152
153 return server.invoke(
154 name, "invoke",
155 new Object[] { invocation }, // args
156 new String[] { 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 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 {}
183
184 public void start() {}
185
186 public void stop() throws Exception {}
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 toString()
199 {
200 String className = getClass().getName();
201 int index = className.lastIndexOf('.');
202
203 return className.substring((index < 0) ? 0 : index) + "[name=" + name + "]";
204 }
205 }
206
207
Save This Page