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1
29
30 package echo2example.chatserver;
31
32 import java.io.IOException  ;
33 import java.io.InputStream ;
34
35 import javax.servlet.ServletException ;
36 import javax.servlet.http.HttpServlet ;
37 import javax.servlet.http.HttpServletRequest ;
38 import javax.servlet.http.HttpServletResponse ;
39 import javax.xml.parsers.DocumentBuilder ;
40 import javax.xml.parsers.DocumentBuilderFactory ;
41 import javax.xml.parsers.ParserConfigurationException ;
42 import javax.xml.transform.Transformer ;
43 import javax.xml.transform.TransformerException ;
44 import javax.xml.transform.TransformerFactory ;
45 import javax.xml.transform.dom.DOMSource ;
46 import javax.xml.transform.stream.StreamResult ;
47
48 import org.w3c.dom.Document ;
49 import org.w3c.dom.Element ;
50 import org.w3c.dom.NodeList ;
51 import org.w3c.dom.Text ;
52 import org.xml.sax.SAXException ;
53
54
57 public class ChatServerServlet extends HttpServlet {
58
59 private static final Server server = new Server();
60
61
64 protected void doPost(HttpServletRequest request, HttpServletResponse response)
65 throws ServletException , IOException {
66 Document requestDocument = loadRequestDocument(request);
67 Document responseDocument = createResponseDocument();
68 processUserAdd(requestDocument, responseDocument);
69 processUserRemove(requestDocument, responseDocument);
70 processPostMessage(requestDocument, responseDocument);
71 processGetMessages(requestDocument, responseDocument);
72 renderResponseDocument(response, responseDocument);
73 }
74
75
81 private Document createResponseDocument()
82 throws IOException {
83 try {
84 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
85 factory.setNamespaceAware(true);
86 DocumentBuilder builder = factory.newDocumentBuilder();
87 Document document = builder.newDocument();
88 document.appendChild(document.createElement("chat-server-response"));
89 return document;
90 } catch (ParserConfigurationException ex) {
91 throw new IOException ("Cannot create document: " + ex);
92 }
93 }
94
95
102 private Document loadRequestDocument(HttpServletRequest request)
103 throws IOException {
104 InputStream in = null;
105 try {
106 request.setCharacterEncoding("UTF-8");
107 in = request.getInputStream();
108 DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
109 factory.setNamespaceAware(true);
110 DocumentBuilder builder = factory.newDocumentBuilder();
111 return builder.parse(in);
112 } catch (ParserConfigurationException ex) {
113 throw new IOException ("Provided InputStream cannot be parsed: " + ex);
114 } catch (SAXException ex) {
115 throw new IOException ("Provided InputStream cannot be parsed: " + ex);
116 } catch (IOException ex) {
117 throw new IOException ("Provided InputStream cannot be parsed: " + ex);
118 } finally {
119 if (in != null) { try { in.close(); } catch (IOException ex) { } }
120 }
121 }
122
123
130 private void processGetMessages(Document requestDocument, Document responseDocument) {
131 String lastRetrievedIdString = requestDocument.getDocumentElement().getAttribute("last-retrieved-id");
132 Message[] messages;
133 if (lastRetrievedIdString == null || lastRetrievedIdString.trim().length() == 0) {
134 messages = server.getRecentMessages();
135 } else {
136 long lastRetrievedId = Long.parseLong(lastRetrievedIdString);
137 messages = server.getMessages(lastRetrievedId);
138 }
139 for (int i = 0; i < messages.length; ++i) {
140 Element messageElement = responseDocument.createElement("message");
141 messageElement.setAttribute("id", Long.toString(messages[i].getId()));
142 if (messages[i].getUserName() != null) {
143 messageElement.setAttribute("user-name", messages[i].getUserName());
144 }
145 messageElement.setAttribute("time", Long.toString(messages[i].getPostTime()));
146 messageElement.appendChild(responseDocument.createTextNode(messages[i].getContent()));
147 responseDocument.getDocumentElement().appendChild(messageElement);
148 }
149 }
150
151
158 private void processPostMessage(Document requestDocument, Document responseDocument) {
159 NodeList postMessageNodes = requestDocument.getDocumentElement().getElementsByTagName("post-message");
160 if (postMessageNodes.getLength() == 0) {
161 return;
163 }
164
165 String remoteHost = requestDocument.getDocumentElement().getAttribute("remote-host");
166
167 Element postMessageElement = (Element ) postMessageNodes.item(0);
168 String userName = postMessageElement.getAttribute("user-name");
169 String authToken = postMessageElement.getAttribute("auth-token");
170 NodeList postMessageContentNodes = postMessageElement.getChildNodes();
171 int length = postMessageContentNodes.getLength();
172 for (int i = 0; i < length; ++i) {
173 if (postMessageContentNodes.item(i) instanceof Text ) {
174 server.postMessage(userName, authToken, remoteHost, ((Text ) postMessageContentNodes.item(i)).getNodeValue());
175 }
176 }
177 }
178
179
185 private void processUserAdd(Document requestDocument, Document responseDocument) {
186 NodeList userAddNodes = requestDocument.getDocumentElement().getElementsByTagName("user-add");
187 if (userAddNodes.getLength() == 0) {
188 return;
190 }
191
192 String remoteHost = requestDocument.getDocumentElement().getAttribute("remote-host");
193
194 Element userAddElement = (Element ) userAddNodes.item(0);
196 String userName = userAddElement.getAttribute("name");
197 String authToken = server.addUser(userName, remoteHost);
198
199 Element userAuthElement = responseDocument.createElement("user-auth");
200 if (authToken == null) {
201 userAuthElement.setAttribute("failed", "true");
202 } else {
203 userAuthElement.setAttribute("auth-token", authToken);
204 }
205 responseDocument.getDocumentElement().appendChild(userAuthElement);
206 }
207
208
214 private void processUserRemove(Document requestDocument, Document responseDocument) {
215 NodeList userRemoveNodes = requestDocument.getDocumentElement().getElementsByTagName("user-remove");
216 if (userRemoveNodes.getLength() == 0) {
217 return;
219 }
220
221 Element userRemoveElement = (Element ) userRemoveNodes.item(0);
222 String userName = userRemoveElement.getAttribute("name");
223 String authToken = userRemoveElement.getAttribute("auth-token");
224
225 String remoteHost = requestDocument.getDocumentElement().getAttribute("remote-host");
226
227 server.removeUser(userName, authToken, remoteHost);
228 }
229
230
237 private void renderResponseDocument(HttpServletResponse response, Document responseDocument)
238 throws IOException {
239 response.setContentType("text/xml; charset=UTF-8");
240 try {
241 TransformerFactory tFactory = TransformerFactory.newInstance();
242 Transformer transformer = tFactory.newTransformer();
243 DOMSource source = new DOMSource (responseDocument);
244 StreamResult result = new StreamResult (response.getWriter());
245 transformer.transform(source, result);
246 } catch (TransformerException ex) {
247 throw new IOException ("Unable to write document to OutputStream: " + ex.toString());
248 }
249 }
250 }
251 |
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