ServletAction


1   // Copyright (c) 2003-2007, Jodd Team (jodd.sf.net). All Rights Reserved.
2   
3   package jodd.servlet;
4   
5   import jodd.util.StringUtil;
6   
7   import java.io.IOException  ;
8   import java.lang.reflect.Method  ;
9   
10  import javax.servlet.ServletException  ;
11  import javax.servlet.http.HttpServlet  ;
12  import javax.servlet.http.HttpServletRequest  ;
13  import javax.servlet.http.HttpServletResponse  ;
14  
15  /**
16   * Replacement and enhancement of <code>HttpServlet</code>, containing additional
17   * functionalities. Must be inherited by user.
18   * <p>
19   *
20   * Here both POST and GET requests calls <code>doRequest</code> method, which
21   * is the entering point of the servlet. For more easier work, this servlet
22   * may use one of the helper methods. Helper methods can be grouped in 3
23   * groups:
24   *
25   * <ul>
26   *
27   * <li>invokers - they execute an action. Action may be specified in request
28   * parameter 'action' or internal, during method invocation. Actions are
29   * (names of the) methods in the same <code>ServletAction</code>
30   * implementation. Action methods can help in reducing the number of
31   * <code>ServletAction</code> classes, since one class may be used for
32   * handling more than one request.</li>
33   *
34   * <li>forwarders - perform forwards to specific URL. They also can read
35   * forward destination from the request parameter 'forward'. </ul>
36   *
37   * <li>redirectors - perform redirect to specific URL. They also can read
38   * redirect destination from the request parameter 'redirect'. </ul>
39   * </ul>
40   *
41   * Default forwarders and redirector names given as request parameter are
42   * either 'forward' or 'redirect' respectively. If more than one parameter
43   * is needed, they have to be named as 'forward-...' or 'redirect-...'.
44   */
45  public abstract class ServletAction extends HttpServlet   {
46  
47      // ---------------------------------------------------------------- HTTP method
48  
49      public final static int HTTP_METHOD_UNKNOWN = 0;
50      public final static int HTTP_METHOD_GET = 1;
51      public final static int HTTP_METHOD_POST = 2;
52  
53      private int method = HTTP_METHOD_UNKNOWN;
54  
55  
56      /**
57       * Returns HTTP method (POST/GET) which invoked the action.
58       */
59      public int getHttpMethod() {
60          return method;
61      }
62  
63      /**
64       * Default doGet method, calls {@link #doRequest(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)}.
65       */
66      protected void doGet(HttpServletRequest   request, HttpServletResponse   response) throws IOException  , ServletException   {
67          method = HTTP_METHOD_GET;
68          doRequest(request, response);
69      }
70  
71      /**
72       * Default doPost method, calls {@link #doRequest(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)}.
73       */
74      protected void doPost(HttpServletRequest   request, HttpServletResponse   response) throws IOException  , ServletException   {
75          method = HTTP_METHOD_POST;
76          doRequest(request, response);
77      }
78  
79      /**
80       * Main get/post request handler.
81       */
82      protected void doRequest(HttpServletRequest   request, HttpServletResponse   response) throws IOException  , ServletException   {
83      }
84  
85      // ---------------------------------------------------------------- UTILTIES: forward
86  
87      /**
88       * Performs forward with use of the RequestDispatcher.
89       */
90      public boolean forward(HttpServletRequest   request, HttpServletResponse   response, String   url) throws IOException  , ServletException   {
91          return DispatcherUtil.forward(request, response, url);
92      }
93  
94      /**
95       * Performs forward with use of the RequestDispatcher.
96       * URL is read from the request. If URL doesn't exist, nothing happens.
97       *
98       * @return true if parameter found, false otherwise
99       */
100     public boolean forwardParam(HttpServletRequest   request, HttpServletResponse   response) throws IOException  , ServletException   {
101         String   url = request.getParameter("forward");
102         if (url != null) {
103             return forward(request, response, url);
104         }
105         return false;
106     }
107 
108     /**
109      * Performs forward where URL is read from the request. If URL doesn't exist,
110      * nothing happens.
111      *
112      * @return <code>true</code> if parameter found and forward was successful,
113      *         <code>false</code> otherwise
114      */
115     public boolean forwardParam(HttpServletRequest   request, HttpServletResponse   response, String   s) throws IOException  , ServletException   {
116         String   url = request.getParameter("forward-" + s);
117         if (url != null) {
118             return forward(request, response, url);
119         }
120         return false;
121 
122     }
123 
124 
125     // ---------------------------------------------------------------- UTILTIES: redirect
126 
127     /**
128      * Performs redirection.
129      */
130     protected static void redirect(HttpServletRequest   request, HttpServletResponse   response, String   url) throws IOException   {
131         DispatcherUtil.redirect(request, response, url);
132     }
133 
134     /**
135      * Performs redirection. URL is read from the request. If URL doesn't exist,
136      * nothing happens.
137      *
138      * @return true if parameter found, false otherwise
139      */
140     protected static boolean redirectParam(HttpServletRequest   request, HttpServletResponse   response)  throws IOException   {
141         String   url = request.getParameter("redirect");
142         if (url != null) {
143             redirect(request, response, url);
144             return true;
145         }
146         return false;
147 
148     }
149 
150     /**
151      * Performs redirection where URL is read from the request. If URL doesn't
152      * exist, nothing happens.
153      *
154      * @return true if parameter found, false otherwise
155      */
156     protected static boolean redirectParam(HttpServletRequest   request, HttpServletResponse   response, String   s) throws IOException   {
157         String   url = request.getParameter("redirect-" + s);
158         if (url != null) {
159             redirect(request, response, url);
160             return true;
161         }
162         return false;
163 
164     }
165 
166 
167 
168 
169     // ---------------------------------------------------------------- UTILTIES: invokers
170 
171     /**
172      * Calls a method defined in the request parameter. Method name is read from
173      * the request. If method name is null (doesn't exist in the request) nothing
174      * happens.
175      *
176      * @return true if action was invoked, otherwise false
177      */
178     public String   invokeActionParam(HttpServletRequest   request, HttpServletResponse   response) throws ServletException   {
179         String   actionName = request.getParameter("action");
180         return invokeActionParam(this, request, response, actionName);
181     }
182 
183     /**
184      * Invoke a method from this ServletAction class. Methods name is given as
185      * parameter. If method name is null nothing happens.
186      *
187      * @return null if error, otherwise string mapping
188      */
189     public String   invokeActionParam(Object   servlet, HttpServletRequest   request, HttpServletResponse   response, String   actionName) throws ServletException   {
190         if (actionName == null) {
191             return null;
192         }
193         try {
194             Method   m = servlet.getClass().getMethod(actionName, new Class  [] {HttpServletRequest  .class, HttpServletResponse  .class});
195             Object   result = m.invoke(servlet, new Object  [] {request, response});
196             return StringUtil.toString(result);
197         } catch (Exception   ex) {
198             throw new ServletException  ("Invocation error of action '" + actionName + "': " + ex.getMessage(), ex);
199         }
200     }
201 
202 
203     // ---------------------------------------------------------------- UTILITIES: include
204 
205     /**
206      * Performs include page.
207      */
208     public static boolean include(HttpServletRequest   request, HttpServletResponse   response, String   page) throws IOException  , ServletException   {
209         return DispatcherUtil.include(request, response, page);
210     }
211 
212     public static boolean includeParam(HttpServletRequest   request, HttpServletResponse   response) throws IOException  , ServletException   {
213         String   url = request.getParameter("include");
214         if (url != null) {
215             return include(request, response, url);
216         }
217         return false;
218     }
219 
220     public static boolean includeParam(HttpServletRequest   request, HttpServletResponse   response, String   includeName) throws IOException  , ServletException   {
221         String   url = request.getParameter("include-" + includeName);
222         if (url != null) {
223             return include(request, response, url);
224         }
225         return false;
226     }
227 
228 
229 }
230
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