13-Java Network Programming

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1 JAVA Programming Language JAVA Network Programming IP Address(Internet Protocol Address) URL(Uniform Resource Location) TCP(Transmission Control Protocol) Socket UDP(User Datagram Protocol) Client / Server Programming 2

2 IP Address(1), 32 1 DNS(Domain Name Servic IP Address 3 IP Address(2) 4

3 IP Address(3) / 5 IP Address(4) (decapsulation). 6

4 IP Address(5) InetAddress IP Byte[ ]] getaddress( ); );//// InetAddress IP String gethostaddress( ); );/// IP %d.%d.%d.%d String gethostname( ); );//// String tostring( ); );/// IP Boolean ismulticastaddress( ); );/// InetAddress IP // // IP Static InetAddress[ ]] getallbyname(string host); // // IP Static InetAddress getbyname(string host); // // local host IP Static InetAddress getlocalhost( ); ); 7 IP Address(6) InetAddress InetAddressTest InetAddressTest main(string main(string args[]) args[]) InetAddress InetAddress myip=null, myip=null, myips[]=null; myips[]=null; myip myip = InetAddress.getByName( InetAddress.getByName( ); ); System.out.println(getHostName: System.out.println(getHostName: + myip.gethostname()); myip.gethostname()); System.out.println(getHostAddr: System.out.println(getHostAddr: + myip.gethostaddress()); myip.gethostaddress()); System.out.println( System.out.println( tostring: tostring: + myip.tostring()); myip.tostring()); catch(unknownhostexception catch(unknownhostexception System.out.println(; System.out.println(; myip myip = InetAddress.getByName(selab.soongsil.ac.kr); InetAddress.getByName(selab.soongsil.ac.kr); System.out.println(getHostName: System.out.println(getHostName: + myip.gethostname()); myip.gethostname()); System.out.println(getHostAddr: System.out.println(getHostAddr: + myip.gethostaddress()); myip.gethostaddress()); System.out.println( System.out.println( tostring: tostring: + myip); myip); catch(unknownhostexception catch(unknownhostexception System.out.println(; System.out.println(; myip myip = InetAddress.getLocalHost(); InetAddress.getLocalHost(); System.out.println(getHostName: System.out.println(getHostName: + myip.gethostname()); myip.gethostname()); System.out.println(getHostAddr: System.out.println(getHostAddr: + myip.gethostaddress()); myip.gethostaddress()); catch(unknownhostexception catch(unknownhostexception System.out.println(; System.out.println(; byte byte inet[] inet[] = myip.getaddress(); myip.getaddress(); System.out.print(getHostAddr: System.out.print(getHostAddr: ); ); for(int for(int i=0;i<inet.length;i++) i=0;i<inet.length;i++) System.out.print(inet[i]+.); System.out.print(inet[i]+.); System.out.println(); System.out.println(); System.out.print(getHostAddr: System.out.print(getHostAddr: ); ); for(int for(int i=0;i<inet.length;i++) i=0;i<inet.length;i++) System.out.print(((inet[i]<0) System.out.print(((inet[i]<0)?? (inet[i]+256) (inet[i]+256) : : inet[i])+.); inet[i])+.); System.out.println(); System.out.println(); myips myips = InetAddress.getAllByName(selab.soongsil.ac.kr); InetAddress.getAllByName(selab.soongsil.ac.kr); for(int for(int i=0;i<myips.length;i++) i=0;i<myips.length;i++) System.out.println(getHostName: System.out.println(getHostName: + myips[i].gethostname()); myips[i].gethostname()); System.out.println(getHostAddr: System.out.println(getHostAddr: + myips[i].gethostaddress()); myips[i].gethostaddress()); catch(unknownhostexception catch(unknownhostexception System.out.println(; System.out.println(; 8

5 URL(Uniform Resource Location) URL <URL > 9 URL(2) URL URL Protocol Host TCP Path Anchor URL ( ref, or reference ) # 10

6 URL(3) URLEncoder x-www-form-urlencoded MIME + %xy 3 URLDecoder URLEncoder 11 URL(4) URLConnection, URL URL 1. URL openconnection 2. setup parameter 3. connect

7 URL(5) HTTP(Hyper Text Transfer Protocol) MIME(Multipurpose Internet Mail Extension) HTML 1. (create connection) 2. (request) 3. (respons 4. (close connection) 13 URL(6) HttpURLConnection URLConnection HTTP 14

8 TCP Socket(1) Socket TCP <IP Address port, socket > 15 TCP Socket(2) C TCP 16

9 TCP Socket(3) TCP 17 TCP Socket(4), echo daytime FTP TELNET SMTP HTTP

10 TCP Socket(5) Socket Socket port <socket> 19 TCP Socket(5) Basic process for JAVA Network Program Step 1 Open a socket Step 2 Open an input stream and output stream to the socket Step 3 Read from and write to the stream according to the server s protocol Step 4 Close the streams Step 5 Close the socket 20

TCP Socket(6) ServerSocket Socket / 21 Establishing a Server Step 1 : create a ServerSocket object Register port number, a maximum number of clients Step 2 : listen indefinitely for an attempt by a

11 TCP Socket(6) ServerSocket Socket / 21 Establishing a Server Step 1 : create a ServerSocket object Register port number, a maximum number of clients Step 2 : listen indefinitely for an attempt by a client to connect Call to the ServerSocket accept method Step 3 : to get OutputStream, InputStream object Enable the server to communicate with the client Step 4 : the Server and the client communicate Via the InputStream and OutputStream object Step 5 : the server close the connection By invoking the close method on the Socket 22

12 Establishing a Server - code... // // Step 1: 1: Create a ServerSocket. server = ServerSocket( 5000, 100 ); ); while (( true )) // // Step 2: 2: Wait for for a connection. connection = server.accept(); display.append( Connection + counter + received from: + connection.getinetaddress().gethostname () ());); // // Step 3: 3: Get Get input and output streams. input = DataInputStream( connection.getinputstream() ); ); output = DataOutputStream( connection.getoutputstream() ); ); display.append( \ngot I/O I/O streams\n ); ); // // Step 4: 4: Process connection. display.append( Sending message \Connection successful\\n ); ); output.writeutf ((Connection successful ); ); display.append( Client message: + input.readutf () ());); // // Step 5: 5: Close connection. display.append( \ntransmission complete. + Closing socket.\n\n ); ); connection.close(); ++counter; Establishing a Client Establishing a Client Step 1 : create a Socket object To connect to the server Step 2 : to get OutputStream, InputStream object To get references to the Socket s associated InputStream and OutputStream Step 3 : the server and the client communicate Via the InputStream and OutputStream object Step 4 : the client close the connection By invoking the close method on the Socket 24

13 Establishing a Client - code... // // Step 1: 1: Create a Socket to to make connection. client = Socket( InetAddress.getLocalHost(), 5000 ); ); display.append( Connected to: to: + client.getinetaddress().gethostname() ); ); // // Step 2: 2: Get the input and output streams. input = DataInputStream( client.getinputstream() ); ); output = DataOutputStream( client.getoutputstream() ); ); display.append( \ngot I/O Streams\n ); ); // // Step 3: 3: Process connection. display.append( Server message: + input.readutf() ); ); display.append( \nsending message \Thank you.\\n ); ); output.writeutf( Thank you. ); ); // // Step 4: 4: Close connection. display.append( Transmission complete. + Closing connection.\n ); ); client.close(); TCP Socket(7) ( ) java.net ServerSocket ServerSocket(int port); ServerSocket(int port, int backlog); ServerSocket(int port, int backlog, InetAddress bindaddr); 26

14 TCP Socket(8) ( ) Backlog Argument, Backlog Backlog,. bindaddr Argument, 27 TCP Socket(9) ServerSocket (EchoServerTest) java.io.*; catch catch (IOException (IOException java.io.*; System.err. System.err. println(failure: println(failure: +; +; System.exit( EchoServerTest EchoServerTest System.exit( 1); 1); main(string[] main(string[] args) args) int int port=4444; port=4444; Socket Socket clientsocket clientsocket = null; null; PrintWriter ServerSocket ServerSocket serversocket serversocket = null; PrintWriter socketout socketout = null; PrintWriter(clientSocket.getOutputStream(), PrintWriter(clientSocket.getOutputStream(), tru; tru; BufferedReader if(args.length if(args.length == == 1) 1) BufferedReader socketin socketin = BufferedReader( BufferedReader( InputStreamReader(clientSocket.getInputStream())); InputStreamReader(clientSocket.getInputStream())); String port port = Integer. Integer. parseint(args[0]); String inputline; inputline; parseint(args[0]); catch(numberformatexception catch(numberformatexception while((inputline port port = 4444; while((inputline = socketin.readline()) socketin.readline())!=!= null) null) 4444; socketout.println(inputlin; socketout.println(inputlin; System.out.println( System.out.println( echo: echo: +inputlin; +inputlin; socketin.close(); socketin.close(); socketout.close(); serversocket serversocket = ServerSocket(port); socketout.close(); ServerSocket(port); clientsocket.close(); clientsocket clientsocket = serversocket.accept(); clientsocket.close(); serversocket.accept(); serversocket.close(); serversocket.close(); System.out.println( System.out.println( serversocket: serversocket: +serversocket); catch catch (IOException (IOException +serversocket); System.out.println(Failure: System.out.println( System.out.println( getlocalport: getlocalport: +serversocket.getlocalport()); System.out.println(Failure: +; +; +serversocket.getlocalport()); System.out.println(); System.out.println(); System.out.print( System.out.print( Connected Connected to: to: +clientsocket.getinetaddress()); +clientsocket.getinetaddress()); System.out.println( System.out.println( : : +clientsocket.getport()); +clientsocket.getport()); 28

15 TCP Socket(10) ServerSocket (EchoClientTest) System.out.println ( Connected to: +clientsocket.getinetaddress()); java.io.*; System.out.println ( Connected to: +clientsocket.getinetaddress()); java.io.*; System.out.println ( getport: +clientsocket.getport()); System.out.println ( getport: +clientsocket.getport()); System.out.println (getlocaladdress: +clientsocket.getlocaladdress()); System.out.println (getlocaladdress: +clientsocket.getlocaladdress()); System.out.println ( getlocalport: +clientsocket.getlocalport()); System.out.println ( getlocalport: +clientsocket.getlocalport()); EchoClientTest EchoClientTest System.out.print( : ); System.out.print( : ); main(string main(string args[]) while (( inputline = stdin.readline())!= null ) args[]) while (( inputline = stdin.readline())!= null ) int int port; if (inputline.equals(by) port; if (inputline.equals(by) Socket Socket clientsocket=null; break; clientsocket=null; break; PrintWriter PrintWriter socketout=null; socketout=null; socketout.println (inputlin; BufferedReader BufferedReader socketin=null; socketout.println (inputlin; socketin=null; System.out.println ( echo: + socketin.readline()); System.out.println ( echo: + socketin.readline()); System.out.print( : ); System.out.print( : ); if(args.length if(args.length < 2) 2) System.out.println([USAGE] System.out.println([USAGE] java java EchoClientTest EchoClientTest EchoServer EchoServer Port); Port); socketout.close(); socketout.close(); System.exit( System.exit( 1); 1); socketin.close(); socketin.close(); stdin.close(); stdin.close(); clientsocket.close(); clientsocket.close(); port port = Integer. Integer. parseint(args[1]); catch (UnknownHostException parseint(args[1]); catch (UnknownHostException System.out.println (Failure: +; catch(numberformatexception catch(numberformatexception System.out.println (Failure: +; System.exit(1); port port = 4444; System.exit(1); 4444; catch (Exception catch (Exception System.out.println (Failure: +; System.out.println (Failure: +; String String inputline; inputline; BufferedReader BufferedReader stdin stdin = BufferedReader( BufferedReader( InputStreamReader(System.in)); InputStreamReader(System.in)); clientsocket clientsocket = Socket(args[0], Socket(args[0], port); port); socketin socketin = BufferedReader( BufferedReader( InputStreamReader(clientSocket.getInputStream())); InputStreamReader(clientSocket.getInputStream())); socketout socketout = PrintWriter(clientSocket.getOutputStream(), PrintWriter(clientSocket.getOutputStream(), tru; tru; 29 TCP Socket(11) ( ) Socket Socket, I/O stream InputStream / OutputStream getinputstream / getoutputstream Socket(String host, int port); Socket(InetAddress address, int port); // // host,, // // port // // address IP Address 30

16 TCP Socket(12) Socket (1) java.io.*; java.io.*; EchoPortTest EchoPortTest final final int int ECHO_PORT=7; ECHO_PORT=7; main(string[] main(string[] args) args) Socket Socket socket socket = null; null; PrintWriter PrintWriter socketout socketout = null; null; BufferedReader BufferedReader socketin socketin = null; null; if(args.length if(args.length < 1) 1) System.out.println([USAGE] System.out.println([USAGE] java java EchoPortTest EchoPortTest EchoServer); EchoServer); System.exit( System.exit( 1); 1); socketin.close(); socketin.close(); socketout.close(); socketout.close(); socket.close(); socket.close(); catch(exception catch(exception System.out.println(Failure: +; +; String String inputline; inputline; BufferedReader BufferedReader stdin stdin = BufferedReader( BufferedReader( InputStreamReader(System.in)); InputStreamReader(System.in)); socket socket = Socket(args[0], Socket(args[0], EchoPortTest.ECHO_PORT); EchoPortTest.ECHO_PORT); socketin socketin = BufferedReader( BufferedReader( InputStreamReader(socket.getInputStream())); InputStreamReader(socket.getInputStream())); socketout socketout = PrintWriter(socket.getOutputStream(), PrintWriter(socket.getOutputStream(), tru; tru; while((inputline while((inputline = stdin.readline()) stdin.readline())!=!= null) null) socketout.println(inputlin; socketout.println(inputlin; System.out.println(echo: System.out.println(echo: + socketin.readline()); socketin.readline()); 31 TCP Socket(13) Socket (2) java.io.*; DayTimePortTest final final int intdaytime_port=13; main(string[ ]] args) args) Socket Socket socket socket = null; null; BufferedReader BufferedReader socketin= socketin= null; null; if(args.length if(args.length < 1) 1) System.out.println([USAGE] java javadaytimeporttest DayTimeServer); DayTimeServer); System.exit(1); System.exit(1); socket socket = Socket(args[0],DayTimePortTest.DAYTIME_PORT); socketin= socketin= BufferedReader(InputStreamReader(socket.getInputStream( ))); ))); System.out.println(Day Time: Time: + socketin.readline( socketin.readline( )); )); socketin.close( socketin.close( ); ); socket.close( socket.close( ); ); catch catch (Exception (Exception System.out.println(Failure: +; +; 32

17 UDP(1) UDP DatagramPacket, DatagramSocket 33 UDP(2) UDP / (UdpDayTimeServerTest) java.io.*; java.io.*; java.util.date; java.util.date; UdpDayTimeServerTest UdpDayTimeServerTest main(string[] main(string[] args) args) DatagramSocket DatagramSocket socket=null; socket=null; DatagramPacket DatagramPacket packetout=null; packetout=null; DatagramPacket DatagramPacket packetin=null; packetin=null; byte byte packetbuf[] packetbuf[] = byte[1024]; byte[1024]; String String datestring=null; datestring=null; socket socket = DatagramSocket(13); DatagramSocket(13); for(;;) for(;;) packetin packetin = DatagramPacket(packetBuf, DatagramPacket(packetBuf, 1024); 1024); socket.receive(packetin); socket.receive(packetin); datestring datestring = String( String( Date(). Date(). togmtstring()+\r\n); togmtstring()+\r\n); int int len len = datestring.length(); datestring.length(); int int port port =packetin.getport(); =packetin.getport(); InetAddress InetAddress inet inet = packetin.getaddress(); packetin.getaddress(); packetout packetout = DatagramPacket(dateString.getBytes(), DatagramPacket(dateString.getBytes(), len, len, inet, inet, port); port); socket.send( socket.send( packetout); packetout); System.out.println( System.out.println( Sending: Sending: + datestring); datestring); catch(ioexception catch(ioexception System.out.println(Failure: System.out.println(Failure: +; +; 34

18 UDP(3) UDP / (UdpDayTimeServerTest) java.io.*; java.io.*; UdpDayTimeClientTest UdpDayTimeClientTest main(string[] main(string[] args) args) DatagramSocket DatagramSocket socket=null; socket=null; DatagramPacket DatagramPacket packetout=null; packetout=null; DatagramPacket DatagramPacket packetin=null; packetin=null; byte byte packetbuf[] packetbuf[] = byte[1024]; byte[1024]; InetAddress InetAddress serverinet; serverinet; if(args.length if(args.length < 1) 1) System.out.println([USAGE] System.out.println([USAGE] java java UdpClockTest UdpClockTest DayTimeServer); DayTimeServer); System.exit( System.exit( 1); 1); socket socket = DatagramSocket(); DatagramSocket(); serverinet serverinet = InetAddress.getByName(args[0]); InetAddress.getByName(args[0]); packetout packetout = DatagramPacket(packetBuf, DatagramPacket(packetBuf, 2, 2, serverinet, serverinet, 13); 13); packetin packetin = DatagramPacket(packetBuf, DatagramPacket(packetBuf, 1024); 1024); socket.send( socket.send( packetout); packetout); socket.receive(packetin); socket.receive(packetin); String String daytime daytime = String(packetIn.getData(), String(packetIn.getData(), 0, 0, packetin.getlength()); packetin.getlength()); System.out.println(Day System.out.println(Day Time: Time: + daytim; daytim; socket.close(); socket.close(); catch(ioexception catch(ioexception System.out.println(Failure: System.out.println(Failure: +; +; 35 UDP(4) MulticastSocket IP IP D , UDP 36

19 UDP(5) // // join a Multicast group and send the the group salutations byte[ ]] msg msg = 'H', 'e', 'e','l', 'l', 'l', 'l','o'; InetAddress group = InetAddress.getByName ( ); MulticastSocket s = MulticastSocket(6789); s.joingroup(group); DatagramPacket hi hi = DatagramPacket(msg, msg.length, group, 6789); s.send(hi); // // get get their responses! byte[ ]] buf buf = byte[1000]; DatagramPacket recv = DatagramPacket(buf, buf.length); s.receive(recv); // // OK, I'm I'm done talking --leave the the group... s.leavegroup(group); 37 / (1) SMTP(Send Mail Transfer Protocol), SMTP. HELO localhost SMTP MAIL FROM: RCPT TO: DATA SUBJECT: >. QUIT 38

20 / (2) / Socket ServerSocket Chatting Server Chatting Client 39 / (3) Chatting Server Chatting Client Chatting Client 40

자바-11장N'1-502

자바-11장N'1-502 C h a p t e r 11 java.net.,,., (TCP/IP) (UDP/IP).,. 1 ISO OSI 7 1977 (ISO, International Standards Organization) (OSI, Open Systems Interconnection). 6 1983 X.200. OSI 7 [ 11-1] 7. 1 (Physical Layer),