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Java > Open Source Codes > com > jcorporate > expresso > core > servlet > viewhandler > ViewHandler


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64
65 package com.jcorporate.expresso.core.servlet.viewhandler;
66
67 import com.jcorporate.expresso.core.ExpressoConstants;
68 import com.jcorporate.expresso.core.controller.ControllerException;
69 import com.jcorporate.expresso.core.controller.ControllerResponse;
70 import com.jcorporate.expresso.core.controller.NonHandleableException;
71 import com.jcorporate.expresso.core.servlet.DBServlet;
72 import org.apache.log4j.Logger;
73
74 import javax.servlet.ServletException JavaDoc;
75 import javax.servlet.http.HttpServletRequest JavaDoc;
76 import javax.servlet.http.HttpServletResponse JavaDoc;
77 import java.io.IOException JavaDoc;
78
79
80 public abstract class ViewHandler
81         extends DBServlet {
82     private static Logger log = Logger.getLogger(ViewHandler.class);
83
84     public ViewHandler() {
85     }
86
87     /**
88      * The ViewHandler implementation must implement only this method
89      */
90     public abstract void handleView(ControllerResponse con,
91                                     HttpServletRequest JavaDoc req,
92                                     HttpServletResponse JavaDoc res)
93             throws ServletException JavaDoc, IOException JavaDoc,
94             ControllerException,
95             NonHandleableException;
96
97     /* doController(HttpServletRequest, HttpServletResponse, Hashtable) */
98     /**
99      * Both GET and POST for the ViewHandler simply pass the information
100      * from parameters and form fields on to the named controller object.
101      * The Controller object passes back a series of Inputs, Outputs
102      * and Actions that are a result of the requested Controller
103      *
104      * @param request Standard request object
105      * @param response Standard response object
106      * @throws ServletException If an uncaught exception occurs
107      * @throws IOException If an I/O error occurs while communicating with
108      * the client
109      */
110     public void doGet(HttpServletRequest JavaDoc request, HttpServletResponse JavaDoc response)
111             throws ServletException JavaDoc, IOException JavaDoc {
112         super.doGet(request, response);
113         log.debug("ViewHandler Begins in Get method");
114         process(request, response);
115     } /* doGet(HttpServletRequest, HttpServletResponse) */
116
117
118     /**
119      * Handle POST method, typically from a form. The only difference between
120      * get and post in this servlet is that when processing post, we look
121      * for a parameter with a name of the form "button_xxx", where xxx is
122      * the next state, as the state to controller into might vary depending on
123      * what button the user presses.
124      *
125      * @param req Standard request object
126      * @param res Standard response object
127      * @throws ServletException If an uncaught exception occurs
128      * @throws IOException If an I/O error occurs while communicating with
129      * the client
130      */
131     public void doPost(HttpServletRequest JavaDoc req, HttpServletResponse JavaDoc res)
132             throws ServletException JavaDoc, IOException JavaDoc {
133         super.doPost(req, res);
134         log.debug("ViewHandler Begins in Post method");
135         process(req, res);
136     } /* doPost(HttpServletRequest, HttpServletResponse) */
137
138
139     public String JavaDoc getTitle() {
140         return ("View Handler Servlet");
141     }
142
143     /**
144      * This is a master method that is does the processing for both GET
145      * and POST.
146      * <p/>
147      * <p/>
148      * Creation date: (1/10/01 8:38:52 AM)
149      * author Adam Rossi, PlatinumSolutions
150      *
151      * @param request javax.servlet.http.HttpServletRequest
152      * @param response javax.servlet.http.HttpServletResponse
153      */
154     public void process(HttpServletRequest JavaDoc request,
155                         HttpServletResponse JavaDoc response)
156             throws ServletException JavaDoc, IOException JavaDoc {
157         ControllerResponse res = (ControllerResponse) request.getAttribute(ExpressoConstants.CONTROLLER_RESPONSE_KEY);
158
159         if (res == null) {
160             throw new ServletException JavaDoc("No Controller Response found in request");
161         }
162         try {
163             handleView(res, request, response);
164         } catch (ControllerException ce) {
165             throw new ServletException JavaDoc(ce);
166         } catch (NonHandleableException ce) {
167             throw new ServletException JavaDoc(ce);
168         }
169     }
170 }
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