tomcat-阿里云开发者社区

tomcat

2016-03-31 1901

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简介：

1.public class ChatServlet  
2.    extends HttpServlet implements CometProcessor {  
3.  
4.    protected ArrayList<HttpServletResponse> connections =   
5.        new ArrayList<HttpServletResponse>();  
6.    protected MessageSender messageSender = null;  
7.      
8.    public void init() throws ServletException {  
9.        messageSender = new MessageSender();  
10.        Thread messageSenderThread =   
11.            new Thread(messageSender, "MessageSender[" + getServletContext().getContextPath() + "]");  
12.        messageSenderThread.setDaemon(true);  
13.        messageSenderThread.start();  
14.    }  
15.  
16.    public void destroy() {  
17.        connections.clear();  
18.        messageSender.stop();  
19.        messageSender = null;  
20.    }  
21.  
22.    /** 
23.     * Process the given Comet event. 
24.     *  
25.     * @param event The Comet event that will be processed 
26.     * @throws IOException 
27.     * @throws ServletException 
28.     */  
29.    public void event(CometEvent event)  
30.        throws IOException, ServletException {  
31.        HttpServletRequest request = event.getHttpServletRequest();  
32.        HttpServletResponse response = event.getHttpServletResponse();  
33.        if (event.getEventType() == CometEvent.EventType.BEGIN) {  
34.            log("Begin for session: " + request.getSession(true).getId());  
35.            PrintWriter writer = response.getWriter();  
36.            writer.println("<!doctype html public \"-//w3c//dtd html 4.0 transitional//en\">");  
37.            writer.println("<head><title>JSP Chat</title></head><body bgcolor=\"#FFFFFF\">");  
38.            writer.flush();  
39.            synchronized(connections) {  
40.                connections.add(response);  
41.            }  
42.        } else if (event.getEventType() == CometEvent.EventType.ERROR) {  
43.            log("Error for session: " + request.getSession(true).getId());  
44.            synchronized(connections) {  
45.                connections.remove(response);  
46.            }  
47.            event.close();  
48.        } else if (event.getEventType() == CometEvent.EventType.END) {  
49.            log("End for session: " + request.getSession(true).getId());  
50.            synchronized(connections) {  
51.                connections.remove(response);  
52.            }  
53.            PrintWriter writer = response.getWriter();  
54.            writer.println("</body></html>");  
55.            event.close();  
56.        } else if (event.getEventType() == CometEvent.EventType.READ) {  
57.            InputStream is = request.getInputStream();  
58.            byte[] buf = new byte[512];  
59.            do {  
60.                int n = is.read(buf); //can throw an IOException  
61.                if (n > 0) {  
62.                    log("Read " + n + " bytes: " + new String(buf, 0, n)   
63.                            + " for session: " + request.getSession(true).getId());  
64.                } else if (n < 0) {  
65.                    error(event, request, response);  
66.                    return;  
67.                }  
68.            } while (is.available() > 0);  
69.        }  
70.    }  
71.  
72.    public class MessageSender implements Runnable {  
73.  
74.        protected boolean running = true;  
75.        protected ArrayList<String> messages = new ArrayList<String>();  
76.          
77.        public MessageSender() {  
78.        }  
79.          
80.        public void stop() {  
81.            running = false;  
82.        }  
83.  
84.        /** 
85.         * Add message for sending. 
86.         */  
87.        public void send(String user, String message) {  
88.            synchronized (messages) {  
89.                messages.add("[" + user + "]: " + message);  
90.                messages.notify();  
91.            }  
92.        }  
93.  
94.        public void run() {  
95.  
96.            while (running) {  
97.  
98.                if (messages.size() == 0) {  
99.                    try {  
100.                        synchronized (messages) {  
101.                            messages.wait();  
102.                        }  
103.                    } catch (InterruptedException e) {  
104.                        // Ignore  
105.                    }  
106.                }  
107.  
108.                synchronized (connections) {  
109.                    String[] pendingMessages = null;  
110.                    synchronized (messages) {  
111.                        pendingMessages = messages.toArray(new String[0]);  
112.                        messages.clear();  
113.                    }  
114.                    // Send any pending message on all the open connections  
115.                    for (int i = 0; i < connections.size(); i++) {  
116.                        try {  
117.                            PrintWriter writer = connections.get(i).getWriter();  
118.                            for (int j = 0; j < pendingMessages.length; j++) {  
119.                                writer.println(pendingMessages[j] + "<br>");  
120.                            }  
121.                            writer.flush();  
122.                        } catch (IOException e) {  
123.                            log("IOExeption sending message", e);  
124.                        }  
125.                    }  
126.                }  
127.  
128.            }  
129.  
130.        }  
131.  
132.    }  
133.  
134.}  
135.

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