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1738
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1 package goodjava.webserver;
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2
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3 import java.io.Writer;
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4 import java.io.OutputStreamWriter;
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5 import java.io.BufferedWriter;
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6 import java.io.IOException;
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7 import java.net.Socket;
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8 import java.util.List;
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9 import java.util.ArrayList;
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10 import java.util.Map;
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11 import java.util.HashMap;
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12 import java.util.Collections;
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13 import java.util.Iterator;
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14
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15
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16 public class ServerSentEvents {
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17
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18 private static class Con {
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19 final Socket socket;
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20 final Writer writer;
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21
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22 Con(Socket socket) throws IOException {
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23 this.socket = socket;
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24 this.writer = new BufferedWriter( new OutputStreamWriter( socket.getOutputStream(), "UTF-8" ) );
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25 }
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26 }
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27
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28 private static class EventHandler {
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29 private final List<Con> cons = new ArrayList<Con>();
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30
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31 synchronized void add(Con con) {
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32 cons.add(con);
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33 }
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34
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35 synchronized void write( String url, String content ) {
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36 Iterator<Con> iter = cons.iterator();
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37 while( iter.hasNext() ) {
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38 Con con = iter.next();
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39 Writer writer = con.writer;
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40 try {
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41 writer.write(content);
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42 writer.write("\n\n");
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43 writer.flush();
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44 } catch(IOException e) {
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45 iter.remove();
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46 }
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47 }
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48 if( cons.isEmpty() )
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49 map.remove(url);
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50 }
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51 }
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52
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53 private static final Map<String,EventHandler> map
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54 = Collections.synchronizedMap(new HashMap<String,EventHandler>());
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55
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56 static void add(Socket socket,Request request) throws IOException {
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57 Con con = new Con(socket);
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58
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59 Writer writer = con.writer;
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60 writer.write("HTTP/1.1 200 OK\r\n");
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61 writer.write("Access-Control-Allow-Origin: *\r\n");
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62 writer.write("Cache-Control: no-cache\r\n");
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63 writer.write("Content-Type: text/event-stream\r\n");
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64 writer.write("\r\n");
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65 writer.flush();
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66
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67 String url = request.url();
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68 EventHandler handler;
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69 synchronized(map) {
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70 handler = map.get(url);
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71 if( handler==null ) {
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72 handler = new EventHandler();
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73 map.put(url,handler);
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74 }
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75 }
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76 handler.add(con);
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77 }
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78
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79 public static void write( String url, String content ) {
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80 EventHandler handler = map.get(url);
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81 if( handler != null )
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82 handler.write(url,content);
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83 }
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84
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85 public static String toData(String message) {
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86 if( message.endsWith("\n") )
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87 message = message.substring( 0, message.length() - 1 );
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88 return "data: " + message.replace( "\n", "\ndata: " ) + "\n";
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89 }
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90
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91 public static void writeMessage( String url, String message ) {
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92 write( url, toData(message) );
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93 }
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94
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95 private ServerSentEvents() {} // never
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96 }
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