tut lap trinh tcp socket

7/28/2019 TUT Lap Trinh TCP Socket

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[TUT]JAVA: Lp trnh TCP Socket

Quote:

JAVA: Lp trnh Socket vi TCPNgi son: Nimbus

Ti liu tham kho:1. Gio trnh Lp trnh Hng i tng JAVA -Ngc Anh Th Press -NXB Thng K2. Computer Networking - By James F. Kurose and Keith W. Ross - Addison Wesley

3. Websitehttp://www.planet-source-code.com4. JAVA Lp trnh mng -Nguyn Phng Lan v Hong c Hi -NXB Gio Dc 1.1. Lptrnh Socket vi TCP

1.1.1. Gii thiuTrong phnny chng ta s tm hiu v s pht trin cc ng dng mng. Ta bit li (core)ca mt ng dng mng bao gm mt cp chng trnh mt chng trnh my khch (clientprogram) v mt chng trnh my ch (server program). Khi c hai chng trnh c thi hnh,

tin trnh (process) my khch v my ch c to ra, v hai tin trnh ny lin lc vi nhaubng cch c t v ghi n nhng socket. Khi to ra mt ng dng mng, nhim v ca chngta l vit m cho c chng trnh my khch v my ch.C hai loi ng dng client-server. Mt loi l nhng ng dng client-server m n c hinthc trn nhng giao thc chun c nh ngha trong cc RFC (Request for Comments).Vi nhng ng dng kiu ny th chng trnh my ch v my khch u phi ph hp vinhng quy tc c nu ra trong RFC. V d, mt chng trnh my khch c th hin thcmt chng trnh FTP client, c nh ngha trong [RFC 959], v chng trnh my ch thhin thc mt FTP server, cng phi c nh ngha trong [RFC 959]

Loi cn li ca mt ng dng client-server l mt ng dng server-client gi c quyn

(proprietary). Trng hp ny ng vi ng dng ta thc hin trong bi tp ny. Trong loi ngdng ny th chng trnh my khch ln my ch u khng cn phi ph hp vi bt c RFCno. Mt nh pht trin n l c th to ra c hai chng trnh client v server, v nh pht trinny hon ton iu khin tt c nhng g c trong m lp trnh. Nhng bi v m lp trnh khngc hin thc trn giao thc chun, nnnhng nh pht trin c lp khc s khng th nopht trin m c th tng thch vi ng dng ny. Khi pht trin mt ng dng kiu ny,nhng nh pht trin phi ch khng s dng nhng cng thng dng c nh nghatrong cc RFC.Trong phn k tip ta s nghin cu nhng im mu cht pht trin mt ng dng client-server gi c quyn. Trong qu trnh pht trin, mt trong nhng quyt nh quan trng m nhpht trin cn phi lm l ng dng s chy trn TCP hay trn UDP. TCP th hng kt ni

(connection-oriented) v cung cp nhng knh lung truyn d liu ng tin m qua d lius c truyn gia hai h thng cui. UDP l mt giao thc khng kt ni v gi i nhng gid liu c lp t h thng cui ny n nhng h thng cn li, m khng h bo m d liuc c nhn hay khng. Trong khun kh bi tp ny th ta ch nghin cu mt ng dng nhchy trn TCP.ng dng nh ny c vit bng ngn ng Java, ta chn Java v nhng l do sau y. Th nht,nhng ng dng mng kiu ny s gn gng hn khi vit bng Java; vi Java s c t dng mhn, v mi dng c th d dng gii thch vi c nhng ngi lp trnh mi bt u. Th hai,
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nhng chng trnh client-server lp trnh bng Java gia tng ngy cng thng dng, v n cth tr thnh tiu chun cho lp trnh mng trong vi nm ti. Java l mt ngn ng c lp nntng, n c c ch by li (iu qun cc ngoi l) cng trng m c th gii quyt hu n ccli xy ra trong qu trnh xut/nhp v nhng hot ng mng, v kh nng phn lung (thread)mnh cung cp nhng phng php n gin hin thc nhng server mnh m.

1.1.2. Lp trnh Socket vi TCP

Ta bit rng nhng tin trnh chy trn nhng my khc nhau c th lin lc vi nhay bngcch gi nhng thng ip n socket. Chng ta c th ni mt cch n gin rng mi mt tintrnh th tng t nh mt cn nh v socket ca tin trnh th tng t nh l cnh ca nh.Nh th hin trn hnh v bn di, socket l cnh ca gia tin trnh ng dng (ApplicationProcess) v TCP. Nhng nh pht trin ng dng c th kim sot mi th bn pha lpApplication ca Socket; tuy nhin, c rt t kim sot bn pha lp Transport.By gi ta hy xt k hn s tng tc gia chng trnh client v chng trnh server. Mykhch client phi c nhim v khi to s giao tip vi server. server c th tr li li s giao

tip ban u ny th server cng phi lun lun sn sng. iu ny bao gm 2 yu t. u tin,chng trnh bn server phi ang hot ng, n phi ang chy nh mt tin trnh trc khimy khch tin hnh s giao tip u tin. Th hai, chng trnh bn server phi c sn mt scng (port) c th tip n (welcome) nhng giao tip khi to t bn pha client. S dng stng t nh cn nh/cnh ca i vi process/socket nh ni trn th ta c th xem nh skhi to giao tip u tin bn pha client nh l mt s g ca.Khi mt tin trnh (process) bn server ang chy, mt tin trnh bn client c th khi to mtTCP connection. iu ny c thc bn chng trnh my client bng cch to ra mt itng socket (ta gi n l clientSocket). Khi mt my khch to ra mt i tng socket th ns ch n a ch ca tin trnh my ch, theo cch gi tn, th l a ch IP ca my server.V cng lc to ra i tng clientSocket th TCP client khi to mt three-way handshake(bi tp mng TCP/IP s gii thiu r hn v cch thc ny) v thit lp mt TCP connection viserver. Three-way handshake ny th hon ton n giu vi c chng trnh server ln chngtrnh client.Trong sut qu trnh three-way handshake, tin trnh bn my khch s g vo cng ca tintrnh my ch. Khi server nhn c s g ca ny, n s to ra mt cnh ca mi (tht ra l mtsocket mi) m phc v cho tng client chuyn bit. Trong bi tp ny, cnh ca cho nchnh l mt i tng ServerSocket m ta gi l welcomeSocket. Khi mt my khch gca, chng trnh s vin dn phng thc accept() ca welcomeSocket, phng thc ny s tora mt socket khc cho client. Vo cui qu trnh handshaking ny th mt kt ni TCP s cthit lp gia socket ca client v mt socket mi ca server. T y tr v sau, ta s gi newsocket ny bng tn gi l connection socket

TCP connection uc xem nh l mt ng dn o gia clients socket v server's connectionsocket. Lc ny, tin trnh bn my khch c th gi nhng byte tu n socket ca n, TCPbo m rng tin trnh bn server s nhn (thng qua connection socket) mi byte theo trnh t gi. Hn th na, ngc li tin trnh bn my khch cng c th nhn byte t socket ca nv tin trnh bn server cng c th gi byte n connection socket ca n. iu ny c m t hnh bn di.
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Bi v socket ng mt vai tr quan trng trong nhng ng dng client-server, cho nn nhngng dng client-server thng c gi l socket programming. Trc khi i n ng dng bitp c th, ta s ni v khi nim lung (stream). Theo ngha en lung l mt dng lu chuyn.Theo ngha k thut,mt lung l mt l trnh qua d liu di chuyn i vo hay i ra mt tintrnh (process). Mi mt lung th c th l mt lung vo (input stream) hay l mt lung xut

(output stream) cho mt tin trnh. Nu mt lung l lung vo th n s nh km vi nhngngun vo ca mt tin trnh, v d nh l mt cng c nhp chun (keyboard) hoc mt socketm d liu i vo n t network. Nu mt lung l lung xut, th n s c nh km vi mtvi ngun xut ca tin trnh, v d nh l mt cng c xut chun (mn hnh) hoc mt socketm i ra t n d liu s i vo network.

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1.2. Chng trnh v d 1: Giao nhn file bng IP1.2.1. Cch thc hot ngChng trnh gm mt file duy nht c tn l FileTransfer.java tc l n ch c mt m ngun

cho c hai bn server v client. Sau khi bin dch file .java ny th ta s chy n bng lnh javaFileTransfer. Tip theo chng trnh s yu cu ngi dng chn la computer tr thnhclient hoc server, c th hin nh trn hnh v. Ta nhp vo 1 nu chn l client v nhpvo 2 nu mun my tnh tr thnh server.

Chy chng trnh server modeTu chn 2 phi c chn trc my tnh c ch nh chy server mode, sau mytnh ny s ch i cc kt ni n n. Ta phi nhp tip port number, ng vi server mode nyth ta c th chn bt c port number no ln hn 1024, v nhng port number di 1024 bgi trc v s dng bi h thng (well-known ports). Chng trnh ny cng c th thc hingiao nhn file gia mt server v nhiu my con ng thi trong mt h thng mng nn n syu cu ta nhp vo s lng my client ln nht c th kt ni n server ny.

Chy chng trnh client modeTng t cho pha bn client, chng trnh s yu cu nhp vo a ch ca server (host address),ta c th nhp a ch IP hay nhp vo tn ca my chy server mode u c (trong trng hptrn hnh bn di th tn my chy server mode c a ch IP trong mng LAN l192.168.0.144). Tip tc ta s nhp port number, client phi cng ng chn nhp port numbernh bn server nh bn server chn th mi c th giao nhn file c.

Giao din giao nhn fileSao khi chn xong bc ny th chng trnh c hai my s hin th mt ca s dng GUI gip cho vic giao nhn file c thc hin d dng.

C hai bn server v client u c th gi file bng cch click vo nt Browse chn file v sau click vo nt Send gi file i.Sau khi click Send gi i th chng trnh bn my nhn s hin th mt hp thoi hingi dng c chp nhn nhn file hay khng. Theo m t trn hnh v th mysieutoc.mshome.net (my chy server mode c a ch IP 192.168.0.144 nh hnh trn) gimt file c tn l TestTransferFile.txt cho my khc.


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Sau khi chnnhn file xong th chng trnh s tip tc hin mt hp thoi khc na thngbo rng file c gi hay c nhn. File sau khi nhn s c cha trong cng th mccha file chng trnh.

1.2.2. Hin thc ng dng bng m lp trnh Java:

Code:

//************************************************** ************************// Name: File transfer application

// Description: transfer files on a network

// Source:http://www.planet-source-code.com

// File Name: FileTransfer.java//************************************************** ************************

import java.io.*;import java.net.*;

import java.util.*;

import java.awt.*;

import java.awt.event.*;import javax.swing.*;

public class FileTransfer extends Frame {

public static String strHostAddress = "";

public static int intPortNumber = 0, intMaxClients = 0;public static Vector vecConnectionSockets = null;

public static FileTransfer objFileTransfer;

public static String strFileName = "",strFilePath = "";public static int intCheckChoice = 0;

public static Socket clientSocket = null;

public static ObjectOutputStream outToServer = null;public static ObjectInputStream inFromServer = null;

public static void main (String [] args) throws IOException {BufferedReader stdin = new BufferedReader(new InputStreamReader (System.in));

System.out.println("\nSelect Type for this Computer:");

System.out.println(" 1. Connect to host (i.e This computer is a client)");

System.out.println(" 2. Wait for connections (i.e This computer is a server)");System.out.println();

System.out.print("Please make a choice: ");

System.out.flush();int intChoice = Integer.parseInt(stdin.readLine());


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if (intChoice == 1) { // This computer is a clientSystem.out.print("Please type in the host address: ");

System.out.flush();

strHostAddress = stdin.readLine();System.out.print("Please type in the host port number: ");System.out.flush();

intPortNumber = Integer.parseInt(stdin.readLine());

}

if (intChoice == 2) { //This computer is a server

System.out.print("Give the port number to listen for requests: ");System.out.flush();

intPortNumber = Integer.parseInt(stdin.readLine());

System.out.print("Give the maximum number of clients for this server: ");System.out.flush();

intMaxClients = Integer.parseInt(stdin.readLine());

}

objFileTransfer = new FileTransfer(intChoice);}

public Label lblSelectFile;

public Label lblTitle;public Label lblStudentName;

public TextField tfFile;

public Button btnBrowse;

public Button btnSend;public Button btnReset;

public FileTransfer (int c) {

setTitle("Java - File Transfer");

setSize(300 , 300);setLayout(null);

addWindowListener(new WindowAdapter () { public void windowClosing (WindowEvent e) {

System.exit(0); } } );

lblTitle = new Label("FILE TRANSFER BY IP");

add(lblTitle);

lblTitle.setBounds(80,30,300,30);

lblSelectFile = new Label("Select File:");

add(lblSelectFile);

lblSelectFile.setBounds(15,87,100,20);


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lblStudentName = new Label("Thanh Thien - Thanh Tuan");

add(lblStudentName);

lblStudentName.setBounds(130,270,200,20);

tfFile = new TextField("");add(tfFile);tfFile.setBounds(13,114,200,20);

btnBrowse = new Button("Browse");btnBrowse.addActionListener(new buttonListener());

add(btnBrowse);

btnBrowse.setBounds(223,113,50,20);btnSend = new Button("Send");

btnSend.addActionListener(new buttonListener());

add(btnSend);btnSend.setBounds(64,168,50,20);

btnReset = new Button("Reset");

btnReset.addActionListener(new buttonListener());add(btnReset);

btnReset.setBounds(120,168,50,20);

show();

if (c == 1) { // Client receives fileintCheckChoice = 1;

try {

clientSocket = new Socket (strHostAddress,intPortNumber);

outToServer = new ObjectOutputStream(clientSocket.getOutputStream()) ;outToServer.flush();

inFromServer = new ObjectInputStream(clientSocket.getInputStream());

int intFlag = 0;

while (true) {

Object objRecieved = inFromServer.readObject();

switch (intFlag) {

case 0:


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if (objRecieved.equals("IsFileTransfered")) {

intFlag++;

}break;

case 1:

strFileName = (String) objRecieved;int intOption = JOptionPane.showConfirmDialog(this,clientSocket.getInetAddress().getHostName()+" is sending you "+strFileName+"!\nDo you want to recieve

it?","Recieve Confirm",JOptionPane.YES_NO_OPTION,JOptionPane.QUE

STION_MESSAGE);

if (intOption == JOptionPane.YES_OPTION) {

intFlag++;

} else {

intFlag = 0;

}break;

case 2:

byte[] arrByteOfReceivedFile = (byte[])objRecieved;

FileOutputStream outToHardDisk = new FileOutputStream(strFileName);outToHardDisk.write(arrByteOfReceivedFile);

intFlag = 0;

JOptionPane.showMessageDialog(this,"FileRecieved!","Confirmation",JOptionPane.INFORMATION_ MESSAGE);

break;

}

Thread.yield();}

} catch (Exception e) {System.out.println(e);}

}

if (c == 2) { // Server receives filevecConnectionSockets = new Vector();

intCheckChoice = 2;

try {ServerSocket welcomeSocket = new ServerSocket(intPortNumber,intMaxClients);

while (true) {

vecConnectionSockets.addElement(new ThreadedConnectionSocket(welcomeSocket.accept()));Thread.yield();

}

} catch (IOException ioe) {System.out.println(ioe);}}


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}

public static String showDialog () {

FileDialog fd = new FileDialog(new Frame(),"Select File...",FileDialog.LOAD);

fd.show();return fd.getDirectory()+fd.getFile();}

private class buttonListener implements ActionListener {

public void actionPerformed (ActionEvent ae) {byte[] arrByteOfSentFile = null;

if (ae.getSource() == btnBrowse) {

strFilePath = showDialog();

tfFile.setText(strFilePath);

int intIndex = strFilePath.lastIndexOf("\\");strFileName = strFilePath.substring(intIndex+1);

}

if (ae.getSource() == btnSend) {

try {FileInputStream inFromHardDisk = new FileInputStream (strFilePath);

int size = inFromHardDisk.available();

arrByteOfSentFile = new byte[size];inFromHardDisk.read(arrByteOfSentFile,0,size);

if (intCheckChoice == 2) {// Send file from server

for (int i=0;i


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}

if (intCheckChoice == 1) { // Send file from clientoutToServer.writeObject("IsFileTransfered");

outToServer.flush();

outToServer.writeObject(strFileName);outToServer.flush();outToServer.writeObject(arrByteOfSentFile);


}JOptionPane.showMessageDialog(null,"File

Sent!","Confirmation",JOptionPane.INFORMATION_MESS AGE);

} catch (Exception ex) {}

}

if (ae.getSource() == btnReset) {tfFile.setText("");

}

}

}}

class ThreadedConnectionSocket extends Thread {

public Socket connectionSocket;

public ObjectInputStream inFromClient;

public ObjectOutputStream outToClient;

public ThreadedConnectionSocket (Socket s) {connectionSocket = s;

try {

outToClient = new ObjectOutputStream(connectionSocket.getOutputStrea m());

outToClient.flush();

inFromClient = new ObjectInputStream(connectionSocket.getInputStream( ));} catch (Exception e) {System.out.println(e);}

start();

}

public void run () {


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try {

int intFlag = 0;

String strFileName = "";

while (true) {Object objRecieved = inFromClient.readObject();

switch (intFlag) {case 0:

if (objRecieved.equals("IsFileTransfered")) {intFlag++;

}

break;case 1:

strFileName = (String) objRecieved;

int intOption = JOptionPane.showConfirmDialog(null,connectionSocke

t.getInetAddress().getHostName()+" is sending you "+strFileName+"!\nDo you want to recieveit?","Recieve Confirm",JOptionPane.YES_NO_OPTION,JOptionPane.QUE

STION_MESSAGE);


intFlag++;

} else {

intFlag = 0;}

break;

case 2:byte[] arrByteOfReceivedFile = (byte[])objRecieved;

FileOutputStream outToHardDisk = new FileOutputStream(strFileName);

outToHardDisk.write(arrByteOfReceivedFile);

intFlag = 0;JOptionPane.showMessageDialog(null,"File

Recieved!","Confirmation",JOptionPane.INFORMATION_ MESSAGE);

break;

}Thread.yield();

}

} catch (Exception e) {System.out.println(e);}}


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}

================================================== ========

1.2.3. Gii thch phn hin thc chng trnhChng ta s nghin cu chi tit, tng dngmt trong m chng trnh hiu r c ch hot

ng ca n. Tuy nhin c th d dng nm bt n th ta s nu mt s im mu cht trongchng trnh

1.2.3.1 Nhng im mu cht ca chng trnhTi my chy client modeChng trnh s ti ra 4 stream v mt socket c biu din nh hnh v:

Xt qu trnh gi file: Socket th c gi l clientSocket. Cn lung (stream)inFromHardDisk c kiu l FileInputStream, l mt lung nhp n chng trnh; n th nhkm vi cng my tnh. Mt khi ta chn c ng dn v tn file th d liu ca file s c chy vo lung inFromHardDisk. Cn lung outToServer c kiu l

ObjectOutputStream l mt lung xut ca chng trnh; n c nh km vi clientSocket. Dliu m client gi n mng chy trong lung outToServer.

Xt qu trnh nhn File: Lung inFromServer c kiu l ObjectInputStream, l mt lung nhpn chng trnh; n c nh km vi socket. D liu n t network s chy vo lunginFromServer. Cn lung outToHardDisk c kiu l FileOutputStream, l lung xut ca chngtrnh; n c nh km vi cng, d liu t lung inFromServer s i vo lungoutToHardDisk, t n s ghi file ra cng my tnh

Ti my chy server modeChng trnh s ti ra 4 stream v mt socket c biu din nh hnh v:

Qu trnh giao nhn file v send file cng din ra tng t nh bn client vi 4 lunginFromHardDisk, outToHardDisk, inFromClient, outToClient v connectionSocket c biudin nh trn hnh v. y ta s khng trnh by li. Ch c mt ch quan trng l trong ng dng ny cho php giao nhn file gia mt server vnhiu my con ng thi trong mt h thng mng nn ti u ho qu trnh hot ng th takhai bo thm mt lp na gi l ThreadedConnectionSocket, lp ny nh ngha mt i tngsocket cng tng t nh connectionSocket m t trn nhng lp ny l lp m rng calp Thread, iu ny s tn dng c tnh nng a xu (multithreading) ca Java. V nhngThreadedConnectionSocket li c a vo lp Vector. Kt qu l ta c th giao nhn file giamt server v nhiu client trong mt mng vi tc x l ti u.

1.2.3.2 Phn tch chi tit m ngun ca chng trnh2.3.2.1. Qu trnh khai bo v to i tng

import java.io.*;

import java.net.*;

import java.util.*;


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java.io v java.net l nhng gi trong Java. Gi java.io cha cc lp cho cc lung xut v lungnhp. C th l, gi java.io cha cc lp ObjectOutputStream, ObjectInputStream,FileInputStream, FileOutputStream, nhng lp ny c sdng v m t trn. Cn gijava.net th cung cp nhng lp h tr mng. C th l, n cha cc lp Socket vServerSocket. i tng clientSocket trong chng trnh ny l mt s dn xut t lp Socket.

Cn gi java.util th cha mt vi lp hu chnht m ta s da vo n. Trong chng trnh nyta c s dng lp Vector ca gi ny.

import java.awt.*;

import java.awt.event.*;import javax.swing.*;

Gi java.awt.* cha nhng lp to ra giao din ngi dng ho (GUI), to ra mt giaodin hnh nh d lm vic. Mt thnh phn GUI l mt i tng hnh nh m ngi dngtng tc vi n thng qua chut hoc bn phm. Cc thnh phn ny c th l cc nt (button),nhn (label), trng vn bn (TextField) v.v... Cn java.awt.event.* gip iu qun cc s

kin, khi ngi dng thc hin mt hnh ng nh di chut, nhn phm, nh phm ... Tt c cchnh ng ny to ra mt s kin. C mt s s kin cn c chng trnh iu qun mt cchr rt, ta s phn tch k iu ny khi i vo tng dng m c th. Cn Swing chnh l mt s bsung AWT, n cung cp cho ta nhiu thnh phn giao din ngi dng khc m AWT khng c.Trong chng trnh ny ta c s dng thnh phn JOptionPane ca Swing.

public class FileTransfer extends Frame {

public static String strHostAddress = "";public static int intPortNumber = 0, intMaxClients = 0;

public static Vector vecConnectionSockets = null;

ngha ca nhng dng m trn l ta khai bo mt lp FileTransfer chnh cho chng trnh, lpny lp m rng ca lp Frame. Mt Frame l mt ca s c lp. Cc khung thng cdng trong cc ng dng yu cu giao din ngi dng ho. Tip theo ta khai bo cc binthuc tnh cho class ny, strHostAddress l a ch ca server m client kt ni n,intPortNumber l s th t ca cng giao nhn d liu, intMaxClients l s my client ti akt ni n server cc bin ny s c gn t pha ngi dng. Cn vecConnectionSockets lmt Vector cha cc ThreadedConnectionSocket h tr cho vic nhiu my client kt ni nmt my ch nh bn trn. Trong trng hp ny ta dng kiu Vector v lp Java Vectorcung cp mt dng mng chnh c c c th tng trng khi c thm mt phn t c bsung vo n.

public static FileTransfer objFileTransfer;

Cn objFileTransfer l mt i tng thuc chnh lp FileTransfer, trong trng hp ny ta dng cu t trong lp FileTransfer ny. Mt cu t l mt phng php c bit c cng tnnh ca lp. on m pha di ta s thy i tng objFileTransfer sc khi to bngcch gi cu t objFileTransfer = new FileTransfer(intChoice).

public static String strFileName = "",strFilePath = "";


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public static int intCheckChoice = 0;

Hai bin thuc tnh strFileName v strFilePath s cha tn v ng dn ca file cn gi i. BinintCheckChoice s gip cho ta xc nh my ang chy kiu server mode hay client mode trongqu trnh gi file.

public static Socket clientSocket = null;public static ObjectOutputStream outToServer = null;

public static ObjectInputStream inFromServer = null;

Cc variable clientSocket, outToServer, inFromServer cng c khai bo, v cc tng ny c m t trn cc hnh v 1-8 trn. Lung outToServer c kiu l ObjectOutputStream lmt lung xut ca chng trnh; n c nh km vi socket. D liu m client gi n mngchy trong lung outToServer. Lung inFromServer c kiu l ObjectInputStream, l mt lungnhp n chng trnh; n c nh km vi socket. D liu n t network s chy vo lunginFromServer.

public static void main (String [] args) throws IOException {

BufferedReader stdin = new BufferedReader(new InputStreamReader (System.in));

System.out.println("\nSelect Type for this Computer:");

System.out.println(" 1. Connect to host (i.e This computer is a client)");System.out.println(" 2. Wait for connections (i.e This computer is a server)");

System.out.println();

System.out.print("Please make a choice: ");System.out.flush();

int intChoice = Integer.parseInt(stdin.readLine());

on m s to nn mt i tng lung stdin c kiu l BufferedReader. Lung nhp ny skhi to vi System.in, gn lung ny vi cng c nhp chun (trong trng hp ny l bnphm). Nhng lnh ny cho php chng trnh c c k t nhp t bn phm, t gn vobin intChoice chn kiu server mode hay client mode.

if (intChoice == 1) { // This computer is a client

System.out.print("Please type in the host address: ");System.out.flush();

strHostAddress = stdin.readLine();

System.out.print("Please type in the host port number: ");

System.out.flush();intPortNumber = Integer.parseInt(stdin.readLine());

}

if (intChoice == 2) { //This computer is a serverSystem.out.print("Give the port number to listen for requests: ");

System.out.flush();

intPortNumber = Integer.parseInt(stdin.readLine());System.out.print("Give the maximum number of clients for this server: ");


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System.out.flush();

intMaxClients = Integer.parseInt(stdin.readLine());

}

Nu intChoice bng 2 tc my chn kiu server mode, th ta s yu cu ngi dng chn s th

t cng, chn s my client ti a c th kt ni n. Nu intChoice bng 1 tc my chn kiuclient mode, th ta s yu cu ngi dng nhp vo a ch ca my server, nhp vo s th tcng giao tip vi server. Tt c cc gi tr ny sau c gn vo cc bin cn thit nhtrong on m.

objFileTransfer = new FileTransfer(intChoice);

Dng m ny khito mt i tng objFileTransfer bng cch dng cu t, l hm FileTransferc cng tn vi lp.

public Label lblSelectFile;public Label lblTitle;

public Label lblStudentName;

public TextField tfFile;

public Button btnBrowse;public Button btnSend;

public Button btnReset;

Ta tip tc khai bo cc thnh phn giao din ngi dng ho, n c m t trn hnh v.

public FileTransfer (int c) {

setTitle("Java - File Transfer");

setSize(300 , 300);setLayout(null);

addWindowListener(new WindowAdapter () { public void windowClosing (WindowEvent e) {

System.exit(0); } } );

lblTitle = new Label("FILE TRANSFER BY IP");

add(lblTitle);

lblTitle.setBounds(80,30,300,30);

lblSelectFile = new Label("Select File:");

add(lblSelectFile);

lblSelectFile.setBounds(15,87,100,20);

lblStudentName = new Label("Thanh Thien - Thanh Tuan");

add(lblStudentName);lblStudentName.setBounds(130,270,200,20);


15/30

tfFile = new TextField("");add(tfFile);

tfFile.setBounds(13,114,200,20);

btnBrowse = new Button("Browse");btnBrowse.addActionListener(new buttonListener());

add(btnBrowse);

btnBrowse.setBounds(223,113,50,20);

btnSend = new Button("Send");

btnSend.addActionListener(new buttonListener());

add(btnSend);btnSend.setBounds(64,168,50,20);

btnReset = new Button("Reset");btnReset.addActionListener(new buttonListener());

add(btnReset);

btnReset.setBounds(120,168,50,20);

show();

Trng hp ny ta dng cu t khi to mt i tng, mt cu t khi to mt i tngngay khi to. N trng tn vi lp, trong chng trnh ny nh ngha mt cu t ca lp tnFileTransfer. Trong phn u ca cu t n gin ta ch thit k giao din ngi dng, v d mlnh lblTitle = new Label("FILE TRANSFER BY IP") s gn ni dung cho n l FILETRANSFER BY IP v sau lnh add(lblTitle) s a n ln Frame hin ti, cn cu lnhlblTitle.setBounds(80,30,300,30) c dng tng qut l setBounds(x,y,width,height) thit lp vtr v kch thc ca label ny.

By gi ta hy set nhng cu m lnh sau:btnBrowse = new Button("Browse");

btnBrowse.addActionListener(new buttonListener());add(btnBrowse);

y l qu trnh iu qun s kin khi nhn button Browse. Mt EventListener lng ch mt skin c th do i tng pht sinh. n lt n s gi cc phng php iu qun s kin, c tnl b iu qun s kin. Mt b lng ch s kin [event listener] cung cp cc phng php iu qun s kin ny. Lp thc thi b lng ch trong trng hp ny l lp buttonListener. Lpny s c nh ngha phn sau ca m chng trnh.

================================================== ==================

2.3.2.2. Qu trnh nhn file (Receive file)

Nhn file bn pha client


16/30

Tip theo y s l mt trong nhng phn quan trng ca chng trnh, phn ny m t qu trnh nhn

file bn pha client

if (c == 1) { // Client receives file

intCheckChoice = 1;

Bin c l sxc nh my tnh ang chy mode no, trong trng hp ny c=1 tc my ang chy

mode client, ta gn cho bin intCheckChoice = 1 tip tc xc nh y l mode client trong trng

hp nu c gi file t client.

try {

clientSocket = new Socket (strHostAddress,intPortNumber);

outToServer = new ObjectOutputStream(clientSocket.getOutputStream()) ;


inFromServer = new ObjectInputStream(clientSocket.getInputStream());

Tip theo ta tin hnh to ra mt clientSocket t cc gi tr c sn strHostAddress v intPortNumber. Ta

cng to ra hai lung outToServer v inFromServer nh cp u chng trnh, phng thc

outToServer.flush() s x ht tt c nhng g cn trong lung outToServer ny ra ngoi.V y l qu

trnh nhn file ti client (t server) nn ta s ch cn s dng lung inFromServer, lung ny n nhn

nhng d liu t clientSocket bng phng thc clientSocket.getInputStream().

int intFlag = 0;

while (true) {

Object objRecieved = inFromServer.readObject();

Cn bin c intFlag gip ta thc hin vic x l d liu gi tserver qua 3 giai on bng cch dng lnh

switch. Cn i tng objRecieved c d liu t lung inFromServer.

switch (intFlag) {

case 0:


intFlag++;

}

break;

Giai on 1, chng trnh s kim tra iu kin objRecieved.equals("IsFileTransfered") bi v trong qu

trnh gi file i tserver, chng trnh bn server ghi vo i tng gi i mt chui

"IsFileTransfered", qu trnh nhn client nu objRecieved.equals("IsFileTransfered") = true th ta bit

chc rng d liu c gi i bng cng mt chng trnh bn server, ta kt thc giai on ny bng

vic tng bin intFlag thm mt n v .


17/30

case 1:


int intOption = JOptionPane.showConfirmDialog(this,clientSocket.ge tInetAddress().getHostName()+" is

sending you "+strFileName+"!\nDo you want to recieve it?","Recieve

Confirm",JOptionPane.YES_NO_OPTION,JOptionPane.QUE STION_MESSAGE);


intFlag++;

} else {

intFlag = 0;

}

break;

Qua giai on 2, lc ny intFlag c gi tr l 1, ta ly ra t objRecieved mt gi tr kiu string cha tn

file, tn file ny c thm vo objRecieved trong qu trnh gi file t server, lc ny mt hp thoi

s hin ra bn pha server xc nhn rng ta c mun nhn file khng.

Nu ta chn Yes th intFlag sc tng thm mt n v na, cn ngc li th intFlag s tr v gi

tr 0.

case 2:




intFlag = 0;

JOptionPane.showMessageDialog(this,"File Recieved!","Confirmation",JOptionPane.INFORMATION_

MESSAGE);

break;

}

Thread.yield();

}


}

Qua n giai on 3, (intFlag lc ny bng 2) sau khi ta chn Yes th d liu ca file cha trong

objRecieved sc c vo mng byte arrByteOfReceivedFile thng qua lnh byte[]

arrByteOfReceivedFile = (byte[])objRecieved


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Lung outToHardDisk sau s to ra mt file c tn trng vi tn file gi, d liu t

arrByteOfReceivedFile sc chy vo lung ny. Nh vy lc ny y bn cng ca my client

mi c to mt file ging c ni dung v tn ging ht nh file c gi tserver, file ny c

nm cng th mc vi file chng trnh.

Chng trnh cng hin th mt hp thoi bo cho ta bit file c nhn.

Cu m lnh Thread.yield() c tc dng khi m mt xu (thread) khng c vic g lm na, th n cth gi phng thc yield() ny bo cho b lp lch (scheduler) bit thc thi mt thread khc. Cn

on m try ... catch c dng iu qun cc ngoi l (exception) hay cn gi l by li.

Nhn file bn server

By gi ta xt tip n trng hp nhn file bn server:

if (c == 2) { // Server receives file

vecConnectionSockets = new Vector();

intCheckChoice = 2;

try {

ServerSocket welcomeSocket = new ServerSocket(intPortNumber,intMaxClients);

while (true) {

vecConnectionSockets.addElement(new ThreadedConnectionSocket(welcomeSocket.accept()));

Thread.yield();

}

} catch (IOException ioe) {System.out.println(ioe);}

}

Nh ta bit th chng trnh bn server phi c nhim v to ra mt welcomeSocket trong qu

trnh three-way handshake thc hin s to ra kt ni TCP gia my server v my client.

welcomeSocket ny c to ra da vo hai gi trintPortNumber v intMaxClients c gn gi tr

trc . V cng ni ttrc chng trnh ny bn server c khnng ng thi transfer file vi

nhiu my client nn nu ch to ra mt connectionSocket th khng nn ta phi ra mt Vector cc

connectionSocket v ti u ho qu trnh thc thi th ta dng chc nng multithreading ca Java

bng cch to s dng cc i tng ConnectionSocket dng c tch hp sn trong class

ThreadedConnectionSocket. Cc i tng ca class ThreadedConnectionSocket c nh ngha l

welcomeSocket.accept() v ni c a vo Vector thng qua phng thc addElement ca i tng

Vector vecConnectionSockets. Sau y ta s tm hiu k v class ThreadedConnectionSocket mi c

to thm.

class ThreadedConnectionSocket extends Thread {

public Socket connectionSocket;

public ObjectInputStream inFromClient;

public ObjectOutputStream outToClient;


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Class ThreadedConnectionSocket ny l mt lp m rng ca lp Thread nn n c tnh nng a xu,

cc thuc tnh ca lp ny bao gm mt connectionSocket v hai lung nh cp phn u l

inFromClient v outToClient.

public ThreadedConnectionSocket (Socket s) {

connectionSocket = s;

try {

outToClient = new ObjectOutputStream(connectionSocket.getOutputStrea m());

outToClient.flush();

inFromClient = new ObjectInputStream(connectionSocket.getInputStream( ));


start();

}

Ta cng nh ngha mt cu t trong lp ny, phng thc outToClient.flush() s x ht tt c nhng g

cn trong lung outToClient ny ra ngoi. V y l qu trnh nhn file ti server (t client) nn ta s ch

cn s dng lung inFromClient, lung ny n nhn nhng d liu t connectionSocket bng phng

thc connectionSocket.getInputStream(). Chng trnh bt u thi hnh mt xu bng mt lnh gi

phng php start() thuc v lp Thread. n lt phng php ny triu gi phng php run()

nh ngha cng vic c thc hin.

public void run () {

try {

int intFlag = 0;

String strFileName = "";

while (true) {

Object objRecieved = inFromClient.readObject();

switch (intFlag) {

case 0:


intFlag++;

}

break;

case 1:


int intOption = JOptionPane.showConfirmDialog(null,connectionSocke

t.getInetAddress().getHostName()+" is sending you "+strFileName+"!\nDo you want to recieve

it?","Recieve Confirm",JOptionPane.YES_NO_OPTION,JOptionPane.QUE STION_MESSAGE);


20/30


intFlag++;

} else {

intFlag = 0;

}

break;

case 2:




intFlag = 0;

JOptionPane.showMessageDialog(null,"File Recieved!","Confirmation",JOptionPane.INFORMATION_

MESSAGE);

break;

}

Thread.yield();

}


}

}

Nu quan st k th ta s thy cch x l ca n hon ton ging nh qu trnh nhn file bn client xt

trn. Nhng dng m lnh trong phng php run() hon ton tng tnh qu trnh nhn file bn

client, bin c intFlag gip ta thc hin vic x l d liu gi tclient qua 3 giai on bng lnh switch.

y ta s khng cn phn tch li ba giai on ..

Nh vy cho n lc ny y ta phn tch xong mt cch chi tit qu trnh nhn file ti client t

server v cng phn tch s ging nhau v khc nhau i vi qu trnh nhn file ti server t client (so

vi nhn file ti client). phn ktip ta si vo nghin cu qu trnh gi file ti client v qu trnh gi

file ti server.

================================================== ===========

2.3.2.3. Qu trnh gi file (Send file)

public static String showDialog () {

FileDialog fd = new FileDialog(new Frame(),"Select File...",FileDialog.LOAD);

fd.show();

return fd.getDirectory()+fd.getFile();

}

y l mt hm nh gip cho ta c thchn c file cng vi ng dn ca mt file thng qua


21/30

mt hp thoi quen thuc. Kt qu tr v sl tn th mc + tn file chn. Hm ny sc dng

on m sau ca chng trnh.

Nh cp phn trc, th mt EventListener lng ch mt s kin c thdo i tng pht

sinh. n lt n s gi cc phng php iu qun s kin, c tn l biu qun s kin. Mt b

lng ch s kin [event listener] cung cp cc phng php iu qun s kin ny. Lp thc thi b

lng chtrong trng hp ny l lp buttonListener.

private class buttonListener implements ActionListener {

public void actionPerformed (ActionEvent ae) {

byte[] arrByteOfSentFile = null;

if (ae.getSource() == btnBrowse) {

strFilePath = showDialog();

tfFile.setText(strFilePath);

int intIndex = strFilePath.lastIndexOf("\\");

strFileName = strFilePath.substring(intIndex+1);

}

Nh ta thy trong on m ny th khi ngi dng click vo button Browse (ae.getSource() ==

btnBrowse) th chng trnh s gi hm showDialog() c nh ngha trc, hm ny s tr vo bin

strFilePath tn v ng dn y ca mt file c chn, sau ta li hin th gi tr ny ln

TextField tfFile, sau bng mt vi hm x l chui th ta ly c gi tr tn file v gn vo bin

strFileName. Bin strFileName ny ch cha tn file (v d l TestTransferFile.txt) m khng h c cha

ng dn th mc.

phn ktip ta s xt phn quan trng ca chng trnh, l phn send file (khi ngi dng nhn

button Send)

if (ae.getSource() == btnSend) {

try {

FileInputStream inFromHardDisk = new FileInputStream (strFilePath);

int size = inFromHardDisk.available();

arrByteOfSentFile = new byte[size];

inFromHardDisk.read(arrByteOfSentFile,0,size);

Chng trnh s to ra mt lung nhp c tn inFromHardDisk c kiu l FileInputStream, n lin kt vi

file vi ng dn nm trong bin strFilePath, bin size sxc nh c s byte c thc c m

khng b phong to. Cu lnh inFromHardDisk.read(arrByteOfSentFile,0,size) sc d liu t

strFilePath v ghi vo mng arrByteOfSentFile.

Gi file bn server


22/30

if (intCheckChoice == 2) {// Send file from server

for (int i=0;i


23/30

outToServer, lung ny c gn vi clientSocket.

- ng vi mi bc th ta dng phng thc flush( ) ghi ra d liu ca lung, iu ny bo m rng

tt cu d liu nm nhng lung di c gi i.

JOptionPane.showMessageDialog(null,"File Sent!","Confirmation",JOptionPane.INFORMATION_MESS

AGE);

Sau khi gi d liu ra socket thnh cng th ta hin mt hp thoi thng bo File c gi i.

if (ae.getSource() == btnReset) {

tfFile.setText("");

}

Cn trong trng hp ngi dng nhn button Reset th chng trnh ch xo trng TextField tfFile v

chi ngi dng thao tc li tu.

1.2.4. Nhn xt

Nh vy ta va phn tch xong tng chc nng, t dng m mt trong chng trnh giao nhn file

bng IP. Ta hy nh li rng TCP cung cp dch v giao nhn d liu ng tin. iu ny c ngha rng, nu

file trong qu trnh giao nhn file trong mng bh hng th giao thc TCP s tin hnh giao nhn li file,

bo m rng d liu lun c phn phi chnh xc. S giao nhn tr li ny hon tonn giu i

vi chng trnh ng dng, tc l ngi lp trnh khng cn phi quan tm n s truyn nhn file tr

li (retransmission) ny.

kim tra chng trnh ny th ta phi dch file FileTransfer.java (hay chp nhng file bin dch)

c bn server ln client. Ta cng phi chy chng trnh my chy server mode trc. iu ny s to

ra mt process bn server chi s giao tip t pha my chy client mode. Sau ta chy chng

trnh client mode my client, ta phi bo m rng phi bao gm ng tn a ch ca server (host

address), v phi chn ng s th t cng thit lp sn bn server. Trong mt vi trng hp him

gp th chng trnh s khng giao nhn file c do b firewall, v thta phi bo m rng cng m ta

chn khng b block bi firewall. Sau khi chy xong client mode th chng trnh s to ra mt process

client v thit lp mt TCP connnection gia my chy mode server v my chy mode client. Cui cng,

giao nhn file th ta ch vic chn file trong cng v nhn Send gi i.

================================================== ========

1.3. Chng trnh 2: Giao nhn x l chui

1.3.1. Cch thc hot ng

Chng trnh ny c c im nh sau:

1. Mt my khch c mt dng ch t cng c nhp chun (bn phm) v gi dng ny ra socket ca

n v t n c gi n server

2. Mt my chc mt dng ch t connection socket ca n

3. My ch s thc hin vic o ngc chui (dng) .


24/30

4. My ch s gi dng ch thay i ra connection socket ca n v t dng ch sc gi qua

my khch

5. My khch c dng ch thay i t socket ca n v in dng ch ra mn hnh.

Chng trnh my client c tn l EchoClient.java, v chng trnh my ch c tn l

EchoServer.java.

Mt khi chai chng trnh c bin dch host tng ng, chng trnh bn server phi c

thc thi trc bn server, n s to ra mt process ti server. Nh cp nhng phn trn, tin

trnh (process) my ch s chi cho n khi c s giao tip ca tin trnh my khch. Khi chng

trnh my khch c thc thi, mt tin trnh c to ra my khch, v tin trnh ny s tip xc

vi my ch v thit lp mt TCP connection vi n. Ngi dng ti my khch lc ny y c th s

dng ng dng ny gi tng dng v nhn v dng ch o ngc.

1.3.2. EchoClient.java

Cng tng tnh chng trnh 1 giao nhn file th y, chng trnh EchoClient to ra 3 lung v

mt socket nh c m thnh bn di

Socket th c gi l clientSocket. Cn lung (stream) inFromUser c kiu l BufferedReader, l mt

lung nhp n chng trnh; n c nh km b nhp chun, trong trng hp ny l bn phm. Khi

ngi s dng g k t vo bn phm my tnh, dng k t ny s chy vo lung inFromUser. Lung

inFromServer l mt lung nhp khc ca chng trnh; n c gn vo socket. Nhng k tn t

mng (network) s chy vo lung inFromServer. Cui cng, lung outToServer l mt lung xut ca

chng trnh ca chng trnh; n cng c gn vo socket. Nhng k t m my khch gi n mng

s chy vo lung outToServer.

Phn ghi ch v gii thch c ghi km trong m ngun ca chng trnh

Code:

import java.net.*;

import java.io.*;

public class EchoClient {

public static void main(String args[]){

if (args.length !=1){

System.out.println("Usage: java EchoClient ");

return;

}

// To i tng lin kt vi my ch (thc tch l lin kt vi clientSocket)

ClientConnect client = new ClientConnect(args[0],3456);


25/30

// Nhn d liu t bn phm v gi n my ch x l

client.requestServer();

// Ct t kt ni vi i tng lin kt

client.shutdown();

}

}

// Thit klp lin kt vi my ch thng qua socket v nhn d liu t bn phm

class ClientConnect {

// Lu gii tng kt ni

Socket clientSocket;

// Lung dng gi d liu n clientSocket

DataOutputStream outToServer;

// Lung dng c d liu do my ch gi v

BufferedReader inFromServer;

/*

Phng thc khi dng to kt ni vi my chtheo a ch destination v cng port

*/

public ClientConnect(String destination,int port){

try{

// To socket kt ni pha client

clientSocket = new Socket(destination,port);

// Ly vo lung nhp dng c d liu do my ch gi v

inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

// Ly v lung xut dng gi d liu n socket t chuyn n my ch

outToServer= new DataOutputStream( clientSocket.getOutputStream());

System.out.println("Connected to server at port 3456.");

} catch (Exception e) {

// Nu gp li th in li ra mn hnh

System.out.println(e);

}

}


26/30

/*

Phng thc ny s nhn chui d liu t bn phm v gi n my ch x l

*/

public void requestServer(){

// To lung c d liu t bn phmBufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));

boolean finished=false;

do {

try{

// To menu la chn. S: gi d liu, R: nhn d liu, Q: chm dt

System.out.print("Send, receive, or quit (S/R/Q): ");

System.out.flush();

String line = inFromUser.readLine();

if(line.length()>0){

line=line.toUpperCase();

switch (line.charAt(0)){

// Nu ngi dng chn S, d liu nhp vo sc gi n clientSocket, t chuyn qua my ch

case 'S':

String sendLine = inFromUser.readLine();

outToServer.writeBytes(sendLine);

outToServer.write(13);

outToServer.write(10);


break;

// Nu ngi dng chn R, d liu do my ch x l sc nhn v v in ra

case 'R':

int inByte;

System.out.print(">>>>");

while ((inByte = inFromServer.read()) != '\n')

System.out.write(inByte);

System.out.println();

break;

// Nu ngi dng chn Q, chng trnh s chm dt

case 'Q':


27/30

finished=true;

break;

default:

break;

}

}

}catch (Exception e){

// Nu li xut nhp th in li ra mn hnh

System.out.println(e);

}

} while(!finished);

}

/*

Phng thc ny c dng ng kt ni t my khch vi my ch

*/

public void shutdown(){

try{

clientSocket.close();

}catch (IOException ex){

System.out.println("IO error closing socket");

}

}

}

1.3.3. EchoServer.java

Chng trnh EchoServer cng c gii thch tng tnh chng trnh EchoClient. Phn ghi ch v

gii thch c ghi km trong m ngun ca chng trnh

Code:

import java.net.*;

import java.io.*;

public class EchoServer {

public static void main(String args[]){

try{

/*

To i tng ServerSocket dng lng nghe kt ni t cc my khch gi n cng 3456

*/

ServerSocket welcomeSocket = new ServerSocket(3456);


28/30

int localPort = welcomeSocket.getLocalPort();

System.out.println("Echo Server is listening on port "+localPort+".");

//Chi kt ni t my khch

/*

Lu : n y chng trnh s dng li v chi cho n khi c kt ni xy ra*/

Socket connectionSocket = welcomeSocket.accept();

/*

C kt ni xy ra. Ly cc thng tin t my khch v cho in ra mn hnh

*/

String destName = connectionSocket.getInetAddress().getHostName();

int destPort = connectionSocket.getPort();

System.out.println("Accepted connection to "+destName +" on port "+destPort+".");

//Ly v lung nhp c d liu t connectionSocket, do my khch gi n

/*

Lu : Ta a lung nhp vo b lc lung chuyn i thnh lung BufferReader c khnng c

c mt chui k t bng phng thc readLine()

*/

BufferedReader inFromClient = new BufferedReader(new

InputStreamReader(connectionSocket.getInputStream( )));

// Ly v lung xut ghi d liu vo connectionSocket, t chuyn n my khch

DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream( ));

// Chc vo x l d liu do my khch gi n

boolean finished = false;

do {

// c mt chui k t t connectionSocket do my khch gi n

String inLine = inFromClient.readLine();

// In chui nhn c ra mn hnh

System.out.println("Received: "+inLine);

// So snh chui gi n. Nu l quit th chm dt

if(inLine.equalsIgnoreCase("quit")) finished=true;

// Xl o ngc chui


29/30

String outLine=new EchoString(inLine.trim()).getString();

// Gi tr kt qu v connectionSocket t tr v my khch

for(int i=0;i


30/30

}

}

1.3.4. Kt qu

V sau y l qu trnh trao i gia my khch v my ch:

My khch My ch

Send, receive, or quit (S/R/Q): SHello Server !Send, receive, or quit (S/R/Q): R>>>>! revreS olleH

Received: Hello Server !Sent: ! revreS olleH

Send, receive, or quit (S/R/Q): s123456789Send, receive, or quit (S/R/Q): r>>>>987654321 Received:

123456789Sent: 987654321

Send, receive, or quit (S/R/Q): SHow are you?Send, receive, or quit (S/R/Q): r>>>>?uoy era woH

Received: How are you?Sent: ?uoy era woH

Send, receive, or quit (S/R/Q): q

1.4. Ti liu tham kho:

1. Gio trnh Lp trnh Hng i tng JAVA - Ngc Anh Th Press - NXB Thng K

2. Computer Networking - By James F. Kurose and Keith W. Ross - Addison Wesley

3. Websitehttp://www.planet-source-code.com

4. JAVA Lp trnh mng - Nguyn Phng Lan v Hong c Hi - NXB Gio Dc

(su tm)

tut lap trinh tcp socket

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