1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
|
import java.io.*;
import java.util.Date;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import org.w3c.dom.*;
// xml document will have a number of message elements.
// each message element will have the attributes id, nesting level, title, author, time, ip address
// nesting level will be 0 for root level messages
public class BulletinBoardServlet extends HttpServlet implements SingleThreadModel
{
Document doc = null;
String fileLocation = null;
String title = null;
String backgroundColor = null;
String foregroundColor = null;
String backgroundImage = null;
String indentation = null;
String requestURI = null;
int nextAvailableMessageId = 0;
String fileLocationRealPath = null;
public void init (ServletConfig config) throws ServletException
{
this.fileLocation = config.getInitParameter ("fileLocation");
if (this.fileLocation==null)
{
System.out.println ("Init Parameter fileLocation missing");
return;
}
try
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
this.fileLocationRealPath = config.getServletContext().getRealPath(this.fileLocation);
doc = db.parse(new InputSource(new FileReader(this.fileLocationRealPath)));
NodeList nl = doc.getElementsByTagName ("Title");
title = nl.item(0).getFirstChild().getNodeValue();
nl = doc.getElementsByTagName ("BackgroundColor");
backgroundColor = nl.item(0).getFirstChild().getNodeValue();
nl = doc.getElementsByTagName ("ForegroundColor");
foregroundColor = nl.item(0).getFirstChild().getNodeValue();
nl = doc.getElementsByTagName ("BackgroundImage");
if (!(nl.item(0).getFirstChild()==null))
backgroundImage = nl.item(0).getFirstChild().getNodeValue();
nl = doc.getElementsByTagName ("Indentation");
indentation = nl.item(0).getFirstChild().getNodeValue();
nl = doc.getElementsByTagName ("NextAvailableMessageId");
nextAvailableMessageId = Integer.parseInt(nl.item(0).getFirstChild().getNodeValue());
} catch (Exception e) { doc = null; System.out.println (e.toString()); }
} // end init
private void updateDocument() throws Exception
{
NodeList nl = doc.getElementsByTagName ("NextAvailableMessageId");
nl.item(0).getFirstChild().setNodeValue(String.valueOf(++nextAvailableMessageId));
PrintWriter pw = new PrintWriter(new FileWriter(this.fileLocationRealPath));
String s = "";
s += doc.getDocumentElement();
pw.println (s);
pw.close();
} // end updateDocument
private Node getMessageById (int id)
{
NodeList nl = doc.getElementsByTagName ("Message");
int i = nl.getLength();
for (int j=0; j<i; j++)
if (id==Integer.parseInt(nl.item(j).getAttributes().getNamedItem("Id").getNodeValue()))
return nl.item(j);
return null;
} // end getMessageById
private void presentMainPage (PrintWriter pw)
{
pw.println (" <center>");
pw.println (" <b>Welcome to " + title+"!</b>");
pw.println (" <br><br>");
pw.println (" </center>");
NodeList nl = doc.getElementsByTagName ("Message");
int i = nl.getLength();
for (int j=0; j<i; j++)
{
NamedNodeMap attr = nl.item(j).getAttributes();
StringBuffer indentation = new StringBuffer();
int k1 = Integer.parseInt (attr.getNamedItem("NestingLevel").getNodeValue());
for (int k2=0; k2<k1; k2++)
indentation.append (this.indentation);
pw.println (" <b><a href='"+requestURI+"?action=showMessage&id="+attr.getNamedItem("Id").getNodeValue()+"'>"+indentation.toString()+attr.getNamedItem("Title").getNodeValue()+"</a></b> "+attr.getNamedItem("Author").getNodeValue()+" <i>"+attr.getNamedItem("Time").getNodeValue()+"</i><br>");
}
pw.println (" <center>");
pw.println (" <br><a href='"+requestURI+"?action=presentAddMessageForm'>Add a Message</a>");
pw.println (" </center>");
} // end presentMainPage
private void showMessage (HttpServletRequest req, PrintWriter pw) throws Exception
{
String id = req.getParameter("id");
Node n = getMessageById (Integer.parseInt(id));
if (n==null)
throw new Exception ("Message Not Found");
NamedNodeMap attr = n.getAttributes();
String title = attr.getNamedItem("Title").getNodeValue();
pw.println (" <center>");
pw.println (" <b>"+title+"</b><br><br>");
pw.println (" "+attr.getNamedItem("Author").getNodeValue()+"<br>");
pw.println (" <i>"+attr.getNamedItem("Time").getNodeValue()+"</i><br>");
pw.println (" <i>"+attr.getNamedItem("IpAddress").getNodeValue()+"</i><br>");
pw.println (" <p><table><tr><td>");
BufferedReader br = new BufferedReader (new StringReader(n.getFirstChild().getNodeValue()));
String line = null;
while ((line=br.readLine())!=null)
{
if (line.startsWith("http://"))
pw.println (" <a href='"+line+"'>" + line + "</a><br>");
else
pw.println (" " + line + "<br>");
}
pw.println (" </td></tr></table></p>");
pw.println (" <p><a href='"+requestURI+"?action=presentReplyMessageForm&id="+id+"'>Reply</a></p>");
pw.println (" </center>");
} // end showMessage
private void presentAddMessageForm (PrintWriter pw)
{
pw.println (" <center>");
pw.println (" <form method='post' action='"+requestURI+"?action=addMessage'><br>");
pw.println (" <table border='3'>");
pw.println (" <tr>");
pw.println (" <td colspan='2'><b>Add Message:</b></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Title:</td>");
pw.println (" <td><input type='text' name='title' cols='250' size='64'></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Author:</td>");
pw.println (" <td><input type='text' name='author' cols='250' size='64'></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Text:</td>");
pw.println (" <td><textarea name='text' rows='7' cols='50'></textarea></td>");
pw.println (" </tr>");
pw.println (" </table>");
pw.println (" <input type='submit' value='Submit Form'>");
pw.println (" <input type='reset' value='Reset Form'>");
pw.println (" </form>");
pw.println (" </center>");
} // end presentAddMessageForm
private void presentReplyMessageForm (HttpServletRequest req, PrintWriter pw) throws Exception
{
String id = req.getParameter ("id");
Node n = getMessageById (Integer.parseInt(id));
if (n==null)
throw new Exception ("Message to Reply Not Found");
String title = n.getAttributes().getNamedItem("Title").getNodeValue();
if (!(title.startsWith("Re:")))
title = "Re:" + title;
pw.println (" <center>");
pw.println (" <form method='post' action='"+requestURI+"?action=addMessage&replyMessageId="+id+"'><br>");
pw.println (" <table border='3'>");
pw.println (" <tr>");
pw.println (" <td colspan='2'><b>Reply to Message:</b></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Title:</td>");
pw.println (" <td>"+title+"</td>");
pw.println (" <td><input type='hidden' name='title' value='"+title+"'></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Author:</td>");
pw.println (" <td><input type='text' name='author' cols='250' size='64'></td>");
pw.println (" </tr>");
pw.println (" <tr>");
pw.println (" <td>Text:</td>");
pw.println (" <td><textarea name='text' rows='7' cols='50'></textarea></td>");
pw.println (" </tr>");
pw.println (" </table>");
pw.println (" <input type='submit' value='Submit Form'>");
pw.println (" <input type='reset' value='Reset Form'>");
pw.println (" </form>");
pw.println (" </center>");
} // end presentReplyMessageForm
private void addMessage (HttpServletRequest req) throws Exception
{
String nestingLevel = null;
String author = req.getParameter ("author");
String title = req.getParameter ("title");
String text = req.getParameter ("text");
String replyMessageId = req.getParameter ("replyMessageId");
Element messageElement = doc.createElement ("Message");
if (replyMessageId==null)
{
doc.getDocumentElement().appendChild(messageElement);
nestingLevel = "0";
}
else
{
Node n = getMessageById (Integer.parseInt(replyMessageId));
if (n==null)
throw new Exception ("Message to Reply Not Found");
n.appendChild (messageElement);
nestingLevel = String.valueOf ((Integer.parseInt(n.getAttributes().getNamedItem("NestingLevel").getNodeValue()))+1);
}
messageElement.setAttribute ("Id", String.valueOf(nextAvailableMessageId));
messageElement.setAttribute ("Title", title);
messageElement.setAttribute ("Author", author);
messageElement.setAttribute ("Time", new Date().toString());
messageElement.setAttribute ("IpAddress", req.getRemoteAddr());
messageElement.setAttribute ("NestingLevel", nestingLevel);
messageElement.appendChild (doc.createTextNode(text));
updateDocument();
} // end addMessage
public void service (HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException
{
if (this.requestURI==null)
this.requestURI = req.getRequestURI();
String action = req.getParameter ("action");
res.setContentType("text/html");
PrintWriter pw = res.getWriter();
pw.println ("<html>");
pw.println (" <head><title>"+title+"</title></head>");
if (backgroundImage==null)
pw.println (" <body text='"+foregroundColor+"' bgcolor='"+backgroundColor+"'>");
else
pw.println (" <body background='"+backgroundImage+"' text='"+foregroundColor+"' bgcolor='"+backgroundColor+"'>");
try
{
if (action==null)
presentMainPage (pw);
else if (action.equals("showMessage"))
showMessage (req, pw);
else if (action.equals("presentAddMessageForm"))
presentAddMessageForm (pw);
else if (action.equals("presentReplyMessageForm"))
presentReplyMessageForm (req, pw);
else if (action.equals("addMessage"))
{
addMessage (req);
res.sendRedirect (requestURI);
}
} catch (Exception e) { pw.println (e.toString()); }
pw.println (" </body>");
pw.println ("</html>");
pw.flush();
pw.close();
} // end service
} // end class BulletinBoardServlet
|