Jake Slack | 03928ae | 2014-05-13 18:41:56 -0700 | [diff] [blame] | 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.Request; |
| 28 | |
| 29 | |
| 30 | /* ------------------------------------------------------------ */ |
| 31 | /** ScopedHandler. |
| 32 | * |
| 33 | * A ScopedHandler is a HandlerWrapper where the wrapped handlers |
| 34 | * each define a scope. When {@link #handle(String, Request, HttpServletRequest, HttpServletResponse)} |
| 35 | * is called on the first ScopedHandler in a chain of HandlerWrappers, |
| 36 | * the {@link #doScope(String, Request, HttpServletRequest, HttpServletResponse)} method is |
| 37 | * called on all contained ScopedHandlers, before the |
| 38 | * {@link #doHandle(String, Request, HttpServletRequest, HttpServletResponse)} method |
| 39 | * is called on all contained handlers. |
| 40 | * |
| 41 | * <p>For example if Scoped handlers A, B & C were chained together, then |
| 42 | * the calling order would be:<pre> |
| 43 | * A.handle(...) |
| 44 | * A.doScope(...) |
| 45 | * B.doScope(...) |
| 46 | * C.doScope(...) |
| 47 | * A.doHandle(...) |
| 48 | * B.doHandle(...) |
| 49 | * C.doHandle(...) |
| 50 | * <pre> |
| 51 | * |
| 52 | * <p>If non scoped handler X was in the chained A, B, X & C, then |
| 53 | * the calling order would be:<pre> |
| 54 | * A.handle(...) |
| 55 | * A.doScope(...) |
| 56 | * B.doScope(...) |
| 57 | * C.doScope(...) |
| 58 | * A.doHandle(...) |
| 59 | * B.doHandle(...) |
| 60 | * X.handle(...) |
| 61 | * C.handle(...) |
| 62 | * C.doHandle(...) |
| 63 | * <pre> |
| 64 | * |
| 65 | * <p>A typical usage pattern is:<pre> |
| 66 | * private static class MyHandler extends ScopedHandler |
| 67 | * { |
| 68 | * public void doScope(String target, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException |
| 69 | * { |
| 70 | * try |
| 71 | * { |
| 72 | * setUpMyScope(); |
| 73 | * super.doScope(target,request,response); |
| 74 | * } |
| 75 | * finally |
| 76 | * { |
| 77 | * tearDownMyScope(); |
| 78 | * } |
| 79 | * } |
| 80 | * |
| 81 | * public void doHandle(String target, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException |
| 82 | * { |
| 83 | * try |
| 84 | * { |
| 85 | * doMyHandling(); |
| 86 | * super.doHandle(target,request,response); |
| 87 | * } |
| 88 | * finally |
| 89 | * { |
| 90 | * cleanupMyHandling(); |
| 91 | * } |
| 92 | * } |
| 93 | * } |
| 94 | * </pre> |
| 95 | */ |
| 96 | public abstract class ScopedHandler extends HandlerWrapper |
| 97 | { |
| 98 | private static final ThreadLocal<ScopedHandler> __outerScope= new ThreadLocal<ScopedHandler>(); |
| 99 | protected ScopedHandler _outerScope; |
| 100 | protected ScopedHandler _nextScope; |
| 101 | |
| 102 | /* ------------------------------------------------------------ */ |
| 103 | /** |
| 104 | * @see org.eclipse.jetty.server.handler.HandlerWrapper#doStart() |
| 105 | */ |
| 106 | @Override |
| 107 | protected void doStart() throws Exception |
| 108 | { |
| 109 | try |
| 110 | { |
| 111 | _outerScope=__outerScope.get(); |
| 112 | if (_outerScope==null) |
| 113 | __outerScope.set(this); |
| 114 | |
| 115 | super.doStart(); |
| 116 | |
| 117 | _nextScope= (ScopedHandler)getChildHandlerByClass(ScopedHandler.class); |
| 118 | |
| 119 | } |
| 120 | finally |
| 121 | { |
| 122 | if (_outerScope==null) |
| 123 | __outerScope.set(null); |
| 124 | } |
| 125 | } |
| 126 | |
| 127 | |
| 128 | /* ------------------------------------------------------------ */ |
| 129 | /* |
| 130 | */ |
| 131 | @Override |
| 132 | public final void handle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException |
| 133 | { |
| 134 | if (_outerScope==null) |
| 135 | doScope(target,baseRequest,request, response); |
| 136 | else |
| 137 | doHandle(target,baseRequest,request, response); |
| 138 | } |
| 139 | |
| 140 | /* ------------------------------------------------------------ */ |
| 141 | /* |
| 142 | * Scope the handler |
| 143 | */ |
| 144 | public abstract void doScope(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) |
| 145 | throws IOException, ServletException; |
| 146 | |
| 147 | /* ------------------------------------------------------------ */ |
| 148 | /* |
| 149 | * Scope the handler |
| 150 | */ |
| 151 | public final void nextScope(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) |
| 152 | throws IOException, ServletException |
| 153 | { |
| 154 | // this method has been manually inlined in several locations, but |
| 155 | // is called protected by an if(never()), so your IDE can find those |
| 156 | // locations if this code is changed. |
| 157 | if (_nextScope!=null) |
| 158 | _nextScope.doScope(target,baseRequest,request, response); |
| 159 | else if (_outerScope!=null) |
| 160 | _outerScope.doHandle(target,baseRequest,request, response); |
| 161 | else |
| 162 | doHandle(target,baseRequest,request, response); |
| 163 | } |
| 164 | |
| 165 | /* ------------------------------------------------------------ */ |
| 166 | /* |
| 167 | * Do the handler work within the scope. |
| 168 | */ |
| 169 | public abstract void doHandle(String target, Request baseRequest, HttpServletRequest request, HttpServletResponse response) |
| 170 | throws IOException, ServletException; |
| 171 | |
| 172 | /* ------------------------------------------------------------ */ |
| 173 | /* |
| 174 | * Do the handler work within the scope. |
| 175 | */ |
| 176 | public final void nextHandle(String target, final Request baseRequest, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException |
| 177 | { |
| 178 | // this method has been manually inlined in several locations, but |
| 179 | // is called protected by an if(never()), so your IDE can find those |
| 180 | // locations if this code is changed. |
| 181 | if (_nextScope!=null && _nextScope==_handler) |
| 182 | _nextScope.doHandle(target,baseRequest,request, response); |
| 183 | else if (_handler!=null) |
| 184 | _handler.handle(target,baseRequest, request, response); |
| 185 | } |
| 186 | |
| 187 | /* ------------------------------------------------------------ */ |
| 188 | protected boolean never() |
| 189 | { |
| 190 | return false; |
| 191 | } |
| 192 | |
| 193 | } |