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1   //
2   //  ========================================================================
3   //  Copyright (c) 1995-2014 Mort Bay Consulting Pty. Ltd.
4   //  ------------------------------------------------------------------------
5   //  All rights reserved. This program and the accompanying materials
6   //  are made available under the terms of the Eclipse Public License v1.0
7   //  and Apache License v2.0 which accompanies this distribution.
8   //
9   //      The Eclipse Public License is available at
10  //      http://www.eclipse.org/legal/epl-v10.html
11  //
12  //      The Apache License v2.0 is available at
13  //      http://www.opensource.org/licenses/apache2.0.php
14  //
15  //  You may elect to redistribute this code under either of these licenses.
16  //  ========================================================================
17  //
18  
19  package org.eclipse.jetty.server.handler;
20  
21  import java.io.IOException;
22  
23  import javax.servlet.ServletException;
24  import javax.servlet.http.HttpServletRequest;
25  import javax.servlet.http.HttpServletResponse;
26  
27  import org.eclipse.jetty.server.Handler;
28  import org.eclipse.jetty.server.Request;
29  import org.eclipse.jetty.server.Server;
30  import org.eclipse.jetty.util.component.LifeCycle;
31  
32  /* ------------------------------------------------------------ */
33  /** A <code>HandlerWrapper</code> acts as a {@link Handler} but delegates the {@link Handler#handle handle} method and
34   * {@link LifeCycle life cycle} events to a delegate. This is primarily used to implement the <i>Decorator</i> pattern.
35   *
36   */
37  public class HandlerWrapper extends AbstractHandlerContainer
38  {
39      protected Handler _handler;
40  
41      /* ------------------------------------------------------------ */
42      /**
43       *
44       */
45      public HandlerWrapper()
46      {
47      }
48  
49      /* ------------------------------------------------------------ */
50      /**
51       * @return Returns the handlers.
52       */
53      public Handler getHandler()
54      {
55          return _handler;
56      }
57  
58      /* ------------------------------------------------------------ */
59      /**
60       * @return Returns the handlers.
61       */
62      public Handler[] getHandlers()
63      {
64          if (_handler==null)
65              return new Handler[0];
66          return new Handler[] {_handler};
67      }
68  
69      /* ------------------------------------------------------------ */
70      /**
71       * @param handler Set the {@link Handler} which should be wrapped.
72       */
73      public void setHandler(Handler handler)
74      {
75          if (isStarted())
76              throw new IllegalStateException(STARTED);
77  
78          Handler old_handler = _handler;
79          _handler = handler;
80          if (handler!=null)
81              handler.setServer(getServer());
82          
83          if (getServer()!=null)
84              getServer().getContainer().update(this, old_handler, handler, "handler");
85      }
86  
87      /* ------------------------------------------------------------ */
88      /*
89       * @see org.eclipse.thread.AbstractLifeCycle#doStart()
90       */
91      @Override
92      protected void doStart() throws Exception
93      {
94          if (_handler!=null)
95              _handler.start();
96          super.doStart();
97      }
98  
99      /* ------------------------------------------------------------ */
100     /*
101      * @see org.eclipse.thread.AbstractLifeCycle#doStop()
102      */
103     @Override
104     protected void doStop() throws Exception
105     {
106         if (_handler!=null)
107             _handler.stop();
108         super.doStop();
109     }
110 
111     /* ------------------------------------------------------------ */
112     public void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException
113     {
114         if (_handler!=null && isStarted())
115         {
116             _handler.handle(target,baseRequest, request, response);
117         }
118     }
119 
120 
121     /* ------------------------------------------------------------ */
122     @Override
123     public void setServer(Server server)
124     {
125         Server old_server=getServer();
126         if (server==old_server)
127             return;
128 
129         if (isStarted())
130             throw new IllegalStateException(STARTED);
131 
132         super.setServer(server);
133 
134         Handler h=getHandler();
135         if (h!=null)
136             h.setServer(server);
137 
138         if (server!=null && server!=old_server)
139             server.getContainer().update(this, null,_handler, "handler");
140     }
141 
142 
143     /* ------------------------------------------------------------ */
144     @Override
145     protected Object expandChildren(Object list, Class byClass)
146     {
147         return expandHandler(_handler,list,byClass);
148     }
149 
150     /* ------------------------------------------------------------ */
151     public <H extends Handler> H getNestedHandlerByClass(Class<H> byclass)
152     {
153         HandlerWrapper h=this;
154         while (h!=null)
155         {
156             if (byclass.isInstance(h))
157                 return (H)h;
158             Handler w = h.getHandler();
159             if (w instanceof HandlerWrapper)
160                 h=(HandlerWrapper)w;
161             else break;
162         }
163         return null;
164 
165     }
166 
167     /* ------------------------------------------------------------ */
168     @Override
169     public void destroy()
170     {
171         if (!isStopped())
172             throw new IllegalStateException("!STOPPED");
173         Handler child=getHandler();
174         if (child!=null)
175         {
176             setHandler(null);
177             child.destroy();
178         }
179         super.destroy();
180     }
181 
182 }