001    /*
002     $Id: ServletBinding.java,v 1.6 2005/06/18 07:53:58 cstein Exp $
003    
004     Copyright 2005 (C) Guillaume Laforge. All Rights Reserved.
005    
006     Redistribution and use of this software and associated documentation
007     ("Software"), with or without modification, are permitted provided
008     that the following conditions are met:
009    
010     1. Redistributions of source code must retain copyright
011        statements and notices.  Redistributions must also contain a
012        copy of this document.
013    
014     2. Redistributions in binary form must reproduce the
015        above copyright notice, this list of conditions and the
016        following disclaimer in the documentation and/or other
017        materials provided with the distribution.
018    
019     3. The name "groovy" must not be used to endorse or promote
020        products derived from this Software without prior written
021        permission of The Codehaus.  For written permission,
022        please contact info@codehaus.org.
023    
024     4. Products derived from this Software may not be called "groovy"
025        nor may "groovy" appear in their names without prior written
026        permission of The Codehaus. "groovy" is a registered
027        trademark of The Codehaus.
028    
029     5. Due credit should be given to The Codehaus -
030        http://groovy.codehaus.org/
031    
032     THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS
033     ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
034     NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
035     FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
036     THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
037     INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
038     (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
039     SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
040     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
041     STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
042     ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
043     OF THE POSSIBILITY OF SUCH DAMAGE.
044    
045     */
046    package groovy.servlet;
047    
048    import groovy.lang.Binding;
049    import groovy.xml.MarkupBuilder;
050    
051    import java.io.IOException;
052    import java.util.Enumeration;
053    import java.util.HashMap;
054    import java.util.Map;
055    
056    import javax.servlet.ServletContext;
057    import javax.servlet.http.HttpServletRequest;
058    import javax.servlet.http.HttpServletResponse;
059    
060    /**
061     * Servlet-specific binding extension to lazy load the writer or the output
062     * stream from the response.
063     * 
064     * <p>
065     * <h3>Default variables bound</h3>
066     * <ul>
067     * <li><tt>"request"</tt> : the HttpServletRequest object</li>
068     * <li><tt>"response"</tt> : the HttpServletResponse object</li>
069     * <li><tt>"context"</tt> : the ServletContext object </li>
070     * <li><tt>"application"</tt> : same as context</li>
071     * <li><tt>"session"</tt> : convenient for <code>request.getSession(<b>false</b>)</code> - can be null!</li>
072     * <li><tt>"params"</tt> : map of all form parameters - can be empty</li>
073     * <li><tt>"headers"</tt> : map of all <b>request</b> header fields</li>
074     * </ul>
075     * 
076     * <p>
077     * <h3>Implicite bound variables</h3>
078     * <ul>
079     * <li><tt>"out"</tt> : response.getWriter() </li>
080     * <li><tt>"sout"</tt> : response.getOutputStream() </li>
081     * <li><tt>"html"</tt> : new MarkupBuilder(response.getWriter()) </li>
082     * </ul>
083     * </p>
084     * 
085     * @author Guillaume Laforge
086     * @author Christian Stein
087     */
088    public class ServletBinding extends Binding {
089    
090        private final Binding binding;
091    
092        private final ServletContext context;
093    
094        private final HttpServletRequest request;
095    
096        private final HttpServletResponse response;
097    
098        private MarkupBuilder html;
099    
100        /**
101         * Initializes a servlet binding.
102         */
103        public ServletBinding(HttpServletRequest request, HttpServletResponse response, ServletContext context) {
104            this.binding = new Binding();
105            this.request = request;
106            this.response = response;
107            this.context = context;
108    
109            /*
110             * Bind the default variables.
111             */
112            binding.setVariable("request", request);
113            binding.setVariable("response", response);
114            binding.setVariable("context", context);
115            binding.setVariable("application", context);
116    
117            /*
118             * Bind the HTTP session object - if there is one.
119             * Note: we don't create one here!
120             */
121            binding.setVariable("session", request.getSession(false));
122    
123            /*
124             * Bind form parameter key-value hash map.
125             *
126             * If there are multiple, they are passed as an array.
127             */
128            Map params = new HashMap();
129            for (Enumeration names = request.getParameterNames(); names.hasMoreElements();) {
130                String name = (String) names.nextElement();
131                if (!binding.getVariables().containsKey(name)) {
132                    String[] values = request.getParameterValues(name);
133                    if (values.length == 1) {
134                        params.put(name, values[0]);
135                    } else {
136                        params.put(name, values);
137                    }
138                }
139            }
140            binding.setVariable("params", params);
141    
142            /*
143             * Bind request header key-value hash map.
144             */
145            Map headers = new HashMap();
146            for (Enumeration names = request.getHeaderNames(); names.hasMoreElements();) {
147                String headerName = (String) names.nextElement();
148                String headerValue = request.getHeader(headerName);
149                headers.put(headerName, headerValue);
150            }
151            binding.setVariable("headers", headers);
152        }
153    
154        public void setVariable(String name, Object value) {
155            /*
156             * Check sanity.
157             */
158            if (name == null) {
159                throw new IllegalArgumentException("Can't bind variable to null key.");
160            }
161            if (name.length() == 0) {
162                throw new IllegalArgumentException("Can't bind variable to blank key name. [length=0]");
163            }
164            /*
165             * Check implicite key names. See getVariable(String)!
166             */
167            if ("out".equals(name)) {
168                throw new IllegalArgumentException("Can't bind variable to key named '" + name + "'.");
169            }
170            if ("sout".equals(name)) {
171                throw new IllegalArgumentException("Can't bind variable to key named '" + name + "'.");
172            }
173            if ("html".equals(name)) {
174                throw new IllegalArgumentException("Can't bind variable to key named '" + name + "'.");
175            }
176            /*
177             * TODO Check default key names. See constructor(s).
178             */
179            
180            /*
181             * All checks passed, set the variable.
182             */
183            binding.setVariable(name, value);
184        }
185    
186        public Map getVariables() {
187            return binding.getVariables();
188        }
189    
190        /**
191         * @return a writer, an output stream, a markup builder or another requested object
192         */
193        public Object getVariable(String name) {
194            /*
195             * Check sanity.
196             */
197            if (name == null) {
198                throw new IllegalArgumentException("No variable with null key name.");
199            }
200            if (name.length() == 0) {
201                throw new IllegalArgumentException("No variable with blank key name. [length=0]");
202            }
203            /*
204             * Check implicite key names. See setVariable(String, Object)!
205             */
206            try {
207                if ("out".equals(name)) {
208                    return response.getWriter();
209                }
210                if ("sout".equals(name)) {
211                    return response.getOutputStream();
212                }
213                if ("html".equals(name)) {
214                    if (html == null) {
215                        html = new MarkupBuilder(response.getWriter());
216                    }
217                    return html;
218                }
219            } catch (IOException e) {
220                String message = "Failed to get writer or output stream from response.";
221                context.log(message, e);
222                throw new RuntimeException(message, e);
223            }
224            /*
225             * Still here? Delegate to the binding object.
226             */
227            return binding.getVariable(name);
228        }
229    }