1 //========================================================================
2 //$Id: WrappedHandler.java,v 1.2 2005/11/11 22:55:39 gregwilkins Exp $
3 //Copyright 2004-2006 Mort Bay Consulting Pty. Ltd.
4 //------------------------------------------------------------------------
5 //Licensed under the Apache License, Version 2.0 (the "License");
6 //you may not use this file except in compliance with the License.
7 //You may obtain a copy of the License at
8 //http://www.apache.org/licenses/LICENSE-2.0
9 //Unless required by applicable law or agreed to in writing, software
10 //distributed under the License is distributed on an "AS IS" BASIS,
11 //WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 //See the License for the specific language governing permissions and
13 //limitations under the License.
14 //========================================================================
15
16 package org.mortbay.jetty.handler;
17
18 import java.io.IOException;
19
20 import javax.servlet.ServletException;
21 import javax.servlet.http.HttpServletRequest;
22 import javax.servlet.http.HttpServletResponse;
23
24 import org.mortbay.component.LifeCycle;
25 import org.mortbay.jetty.Handler;
26 import org.mortbay.jetty.HandlerContainer;
27 import org.mortbay.jetty.Server;
28
29 /* ------------------------------------------------------------ */
30 /** A <code>HandlerWrapper</code> acts as a {@link Handler} but delegates the {@link Handler#handle handle} method and
31 * {@link LifeCycle life cycle} events to a delegate. This is primarily used to implement the <i>Decorator</i> pattern.
32 * @author gregw
33 */
34 public class HandlerWrapper extends AbstractHandlerContainer
35 {
36 private Handler _handler;
37
38 /* ------------------------------------------------------------ */
39 /**
40 *
41 */
42 public HandlerWrapper()
43 {
44 super();
45 }
46
47 /* ------------------------------------------------------------ */
48 /**
49 * @return Returns the handlers.
50 */
51 public Handler getHandler()
52 {
53 return _handler;
54 }
55
56 /* ------------------------------------------------------------ */
57 /**
58 * @param handler Set the {@link Handler} which should be wrapped.
59 */
60 public void setHandler(Handler handler)
61 {
62 try
63 {
64 Handler old_handler = _handler;
65
66 if (getServer()!=null)
67 getServer().getContainer().update(this, old_handler, handler, "handler");
68
69 if (handler!=null)
70 {
71 handler.setServer(getServer());
72 }
73
74 _handler = handler;
75
76 if (old_handler!=null)
77 {
78 if (old_handler.isStarted())
79 old_handler.stop();
80 }
81 }
82 catch(Exception e)
83 {
84 IllegalStateException ise= new IllegalStateException();
85 ise.initCause(e);
86 throw ise;
87 }
88 }
89
90 /* ------------------------------------------------------------ */
91 /** Add a handler.
92 * This implementation of addHandler calls setHandler with the
93 * passed handler. If this HandlerWrapper had a previous wrapped
94 * handler, then it is passed to a call to addHandler on the passed
95 * handler. Thus this call can add a handler in a chain of
96 * wrapped handlers.
97 *
98 * @param handler
99 */
100 public void addHandler(Handler handler)
101 {
102 Handler old = getHandler();
103 if (old!=null && !(handler instanceof HandlerContainer))
104 throw new IllegalArgumentException("Cannot add");
105 setHandler(handler);
106 if (old!=null)
107 ((HandlerContainer)handler).addHandler(old);
108 }
109
110
111 public void removeHandler (Handler handler)
112 {
113 Handler old = getHandler();
114 if (old!=null && (old instanceof HandlerContainer))
115 ((HandlerContainer)old).removeHandler(handler);
116 else if (old!=null && handler.equals(old))
117 setHandler(null);
118 else
119 throw new IllegalStateException("Cannot remove");
120 }
121
122
123 /* ------------------------------------------------------------ */
124 /*
125 * @see org.mortbay.thread.AbstractLifeCycle#doStart()
126 */
127 protected void doStart() throws Exception
128 {
129 if (_handler!=null)
130 _handler.start();
131 super.doStart();
132 }
133
134 /* ------------------------------------------------------------ */
135 /*
136 * @see org.mortbay.thread.AbstractLifeCycle#doStop()
137 */
138 protected void doStop() throws Exception
139 {
140 super.doStop();
141 if (_handler!=null)
142 _handler.stop();
143 }
144
145 /* ------------------------------------------------------------ */
146 /*
147 * @see org.mortbay.jetty.EventHandler#handle(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
148 */
149 public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch) throws IOException, ServletException
150 {
151 if (_handler!=null && isStarted())
152 _handler.handle(target,request, response, dispatch);
153 }
154
155
156 /* ------------------------------------------------------------ */
157 public void setServer(Server server)
158 {
159 Server old_server=getServer();
160
161 super.setServer(server);
162
163 Handler h=getHandler();
164 if (h!=null)
165 h.setServer(server);
166
167 if (server!=null && server!=old_server)
168 server.getContainer().update(this, null,_handler, "handler");
169 }
170
171
172 /* ------------------------------------------------------------ */
173 protected Object expandChildren(Object list, Class byClass)
174 {
175 return expandHandler(_handler,list,byClass);
176 }
177
178
179 }