Java net programming II

Transcription

1 Java et programmig II Overview The problem Basic backgroud: TCP/IP, ports, Cliet/Server, sockets Commuicatio with sockets java.et (overview) Simple web server implemetatio 1

2 Socket commuicatio Server IP: port: 2000 Request: Server IP: port: The Java.et.Socket Class Coectio is accomplished via object istatiatio q Each Socket object is associated with exactly oe remote host. Sedig ad receivig data is accomplished with output ad iput streams. 2

3 Example: Server ad Cliet - Server import import java.et.*; java.io.*; public class Server { public static void mai(strig[] args) throws IOExceptio { it serverport = 2000; ServerSocket serversocket = ull; 16-5 Example: Server ad Cliet - Server //Create try { server socket serversocket = ew ServerSocket(serverPort); catch (IOExceptio e) { System.err.pritl("Could ot liste o port: " + serverport); System.exit(1);

4 Example: Server ad Cliet - Server //Liste to cliet request ad create cliet socket Socket clietsocket = ull; try { clietsocket = serversocket.accept(); catch (IOExceptio e) { System.err.pritl("Accept failed."); System.exit(1); 16-7 Example: Server ad Cliet - Server //Create I/O streams PritWriter out = ew PritWriter( clietsocket.getoutputstream(), true); BufferedReader i = ew BufferedReader( ew IputStreamReader( clietsocket.getiputstream())); //Commuicate with cliet //Get a strig from cliet, modify it ad set it back //Ca throw I/O exceptio Strig fromcliet = i.readlie(); Strig tocliet = "Readig from " + clietsocket + ": "+ fromcliet; out.pritl(tocliet);

5 Example: Server ad Cliet - Server // Housekeepig: Release resources out.close(); i.close(); clietsocket.close(); serversocket.close(); 16-9 Example: Server ad Cliet - Cliet import java.io.*; import java.et.*; public class Cliet { public static void mai(strig[] args) throws IOExceptio { Socket serversocket = ull; PritWriter out = ull; //sed to server BufferedReader i = ull; //receive from server Strig server = " "; // OR: Strig server = "localhost ; it serverport = 2000;

6 Example: Server ad Cliet - Cliet // Coect to Server try { // Server IP ad port serversocket= ew Socket(server, serverport); out = ew PritWriter(serverSocket.getOutputStream(), true); i = ew BufferedReader(ew IputStreamReader(serverSocket.getIputStream())); catch (UkowHostExceptio e) { System.err.pritl("Ca ot fid host: "+ server); System.exit(1); catch (IOExceptio e) { System.err.pritl("Could't get I/O with: " + server); System.exit(1); Example: Server ad Cliet - Cliet //Commuicate with server //Sed a strig to server ad receive a reply Strig toserver = "Strig from cliet"; out.pritl(toserver); Strig fromserver = i.readlie(); System.out.pritl("Cliet: " + toserver); System.out.pritl("Server: " + fromserver);

7 Example: Server ad Cliet - Cliet //Release resources out.close(); i.close(); serversocket.close(); Example: Server ad Cliet - Cliet Server: Strig fromcliet = i.readlie(); Strig tocliet = "Readig from " + clietsocket + ": "+ fromcliet; out.pritl(tocliet); Cliet: Strig toserver = "Strig from cliet"; out.pritl(toserver); Strig fromserver = i.readlie(); System.out.pritl("Cliet: " + toserver); System.out.pritl("Server: " + fromserver);

8 Example: Server ad Cliet multiple cliets Server rus oly oce After cliet commuicatio both server ad cliet ed What if we eed the server to commuicate with several cliets? Example: Server ad Cliet multiple cliets Whe cliet coectio requests arrived they are queued They ca be serviced oe at a time Or the server ca service cliets simultaeously through the use of threads A thread is a lightweight cocurret process Creatig oe thread per each cliet coectio, cliets are serviced simultaeously

9 Example: Server ad Cliet multiple cliets The basic flow of logic is: while (true) { accept a coectio; create a thread to deal with the cliet; Server Thread 0 Thread 1 Thread Cliet 0 Cliet 1 Cliet Example: Server ad Cliet - multiple cliets //Class Server //serversocket = ew ServerSocket(serverPort); while (true) { //Liste to cliet request (as before)... clietsocket = serversocket.accept(); //Create I/O streams (moved) //Commuicate with cliets ew ServerThread(clietSocket).start(); //executes //thread ru() //clietsocket.close(); //ed while //Error Thread rus //i parallel Helder Daiel

10 Example: Server ad Cliet - multiple cliets public class ServerThread exteds Thread { private Socket clietsocket; public ServerThread (Socket socket) { clietsocket=socket; Example: Server ad Cliet - multiple cliets public void ru() { try { //Create I/O streams (moved from server class) //(we eed differet streams for each cliet) PritWriter writecliet = ew PritWriter(clietSocket.getOutputStream(), true); BufferedReader readcliet = ew BufferedReader( ew IputStreamReader( clietsocket.getiputstream()));

11 Example: Server ad Cliet - multiple cliets //Commuicate with cliet (moved from server class) Strig fromcliet = readcliet.readlie(); Strig tocliet = fromcliet + " set from Server"; writecliet.pritl(tocliet); //Release resources (moved from server class) writecliet.close(); readcliet.close(); clietsocket.close(); catch (IOExceptio e) { e.pritstacktrace(); If we eed to chage the behaviour of the server we eed to rewrite this class Server ad Cliet templates Most of the iteractios betwee a server ad its cliets is structurally similar. Both the TemplateMethod ad the Strategy desig patters ca be used to desig cliet-server iteractios A cocrete server ad a cocrete cliets ca the be implemeted re-usig most of the previously writte code Typically, oly a small class will be eed for implemetig a cocrete cliet. The same applies for a cocrete server. jvo@ualg.pt

12 TemplateCliet ClietDemo ClietDemo() mai(strig[]):void TemplateCliet serversocket: Socket server: Strig serverport: it TemplateCliet(Strig,it) fialize():void behaviour():void start():void ACocreteCliet ACocreteCliet(Strig,it) behaviour():void ClietDemo starts the cliet import java.io.*; public class ClietDemo { public static void mai(strig[] args) throws IOExceptio, ClassNotFoudExceptio { Strig server = "localhost"; // " "; it serverport = 2000; ew ACocreteCliet(server, serverport).start(); ClietDemo ClietDemo() mai(strig[]):void TemplateCliet serversocket: Socket server: Strig serverport: it TemplateCliet(Strig,it) fialize():void behaviour():void start():void ACocreteCliet ACocreteCliet(Strig,it) hdaiel@ualg.pt behaviour():void Helder Daiel

13 TemplateCliet code abstract public class TemplateCliet { protected Socket serversocket = ull; private Strig server; private it serverport; public TemplateCliet (Strig server, it serverport) { this.serverport = serverport; this.server = server; try { //Coect to Server serversocket = ew Socket(this.server, this.serverport); catch (UkowHostExceptio e) { System.err.pritl("Caot fid host: "+ server); System.exit(1); catch (IOExceptio e) { System.err.pritl("Could't get I/O with: "+server); System.exit(1); //Ed costructor TemplateCliet protected void fialize() throws IOExceptio { serversocket.close(); // to be implemeted by subclasses abstract public void behaviour() throws IOExceptio, ClassNotFoudExceptio; public void start() throws IOExceptio, ClassNotFoudExceptio { behaviour(); //Ed class

14 A Cocrete cliet eeds oly to implemet behaviour (ad a costructor) import java.io.*; import java.util.date; class ACocreteCliet exteds TemplateCliet { ACocreteCliet (Strig server, it serverport) { super(server, serverport); A cocrete cliet eeds oly to implemet behaviour (ad a costructor) public void behaviour() throws IOExceptio, ClassNotFoudExceptio { ObjectOutputStream writeserver = ew ObjectOutputStream( serversocket.getoutputstream()); ObjectIputStream readserver = ew ObjectIputStream( serversocket.getiputstream()); Date toserver = ew Date(); writeserver.writeobject(toserver); Date fromserver = (Date) readserver.readobject(); System.out.pritl("Cliet: " + toserver); System.out.pritl("Server: " + fromserver); writeserver.close(); readserver.close(); // eoc

15 The server side ServerDemo ServerDemo() mai(strig[]):void CotextServer serversocket: ServerSocket ruig: boolea behaviourclassname: Strig CotextServer(it,Strig) fialize():void stop():void start():void <<Java Iterface>> IServerBehaviour iitialize(socket):void behaviour():void start():void TemplateServerThread clietsocket: Socket TemplateServerThread() ru():void ServerBehaviourDemo ServerBehaviourDemo() iitialize(socket):void behaviour():void José Valete de Oliveira ServerDemo starts the server public class ServerDemo { public static void mai(strig[] args) throws Exceptio { it sport = 2000; ew CotextServer(sport, ServerBehaviourDemo ).start(); ServerDemo ServerDemo() mai(strig[]):void CotextServer serversocket: ServerSocket ruig: boolea behaviourclassname: Strig CotextServer(it,Strig) fialize():void stop():void start():void <<Java Iterface>> IServerBehaviour iitialize(socket):void behaviour():void start():void TemplateServerThread clietsocket: Socket TemplateServerThread() ru():void ServerBehaviourDemo ServerBehaviourDemo() iitialize(socket):void Need to pass the class ame that implemets the method behaviour(), i.e., ServerBehaviourDemo behaviour():void hdaiel@ualg.pt Helder Daiel 15

16 The CotextServer public class CotextServer { private ServerSocket serversocket; private boolea ruig = false; private Strig behaviourclassname; public CotextServer(it serverport, Strig behaviourclassname) { ruig = false; this.behaviourclassname = behaviourclassname; try { serversocket = ew ServerSocket(serverPort); catch (IOExceptio e) { System.err.pritl("Could ot liste o port: " + serverport); System.exit(1); //Ed costructor The CotextServer protected void fialize() throws IOExceptio { serversocket.close(); public void stop() { ruig = false;

17 The CotextServer public void start() throws Exceptio { ruig = true; while (ruig) { socket clietsocket = ull; try { clietsocket = serversocket.accept(); catch (IOExceptio e) { System.err.pritl("Accept failed."); System.exit(1); //Start a ew Thread for each cliet The CotextServer //eom //eoc //Start a ew Thread for each cliet //Class behaviour ame is obtaied usig reflectio IServerBehaviour behaviour = (IServerBehaviour) Class.forName(behaviourClassName).ewIstace(); behaviour.iitialize(clietsocket); behaviour.start(); IServerBehaviour behaviour = (IServerBehaviour) ServerBehaviourDemo.ewIstace(); For producig: ew ServerBehaviourDemo();

18 The server side ServerDemo ServerDemo() mai(strig[]):void CotextServer serversocket: ServerSocket ruig: boolea behaviourclassname: Strig CotextServer(it,Strig) fialize():void stop():void start():void <<Java Iterface>> IServerBehaviour iitialize(socket):void behaviour():void start():void TemplateServerThread clietsocket: Socket TemplateServerThread() ru():void ServerBehaviourDemo ServerBehaviourDemo() iitialize(socket):void behaviour():void José Valete de Oliveira A iterface for specifyig the type ServerBehaviour <<Java Iterface>> IServerBehaviour import java.et.socket; iitialize(socket):void behaviour():void start():void public iterface IServerBehaviour { void iitialize (Socket clietsocket); void behaviour() throws Exceptio; void start();

19 TemplateServerThread code for cocrete behaviours abstract public class TemplateServerThread exteds Thread implemets IServerBehaviour { protected Socket clietsocket; public void ru() { try { // Commuicate with cliet behaviour(); // Must be implemeted by subclasses clietsocket.close(); catch (Exceptio e) { e.pritstacktrace(); A cocrete behaviour: ServerBehaviourDemo class ServerBehaviourDemo exteds TemplateServerThread { // madatory public void iitialize (Socket clietsocket) { this.clietsocket = clietsocket; This is the oly class we eed to chage to implemet a differet server // madatory public void behaviour() throws Exceptio { // YOUR CODE HERE <<Java Iterface>> IServerBehaviour iitialize(socket):void behaviour():void start():void TemplateServerThread clietsocket: Socket TemplateServerThread() ru():void ServerBehaviourDemo ServerBehaviourDemo() iitialize(socket):void behaviour():void

20 A cocrete behaviour: ServerBehaviourDemo public void behaviour() throws Exceptio { ObjectOutputStream w = ew ObjectOutputStream(clietSocket.getOutputStream()); ObjectIputStream r = ew ObjectIputStream (clietsocket.getiputstream()); Date fromcliet = (Date) r.readobject(); Date tocliet = (Date) fromcliet.cloe(); w.writeobject(tocliet); // Close I/O streams ow w.close(); r.close(); // Ed behaviour //Ed class Server Cliet iteractio Server: Date fromcliet = (Date) readcliet.readobject(); Date tocliet = (Date) fromcliet.cloe(); w.writeobject(tocliet); Cliet: Date toserver = ew Date(); writeserver.writeobject(toserver); Date fromserver = (Date) readserver.readobject(); System.out.pritl("Cliet: " + toserver); System.out.pritl("Server: " + fromserver);

21 Check poit Say you eed a server to: q receive a Strig q Modify it q ad sed back to the cliet What would you do? Simple (HTTP) webserver for GET requests oly http request (GET) Web page Web server Web page Web cliet 42 21

22 Simple webserver for GET requests oly WebServerDemo WebServerDemo() mai(strig[]):void CotextServer serversocket: ServerSocket ruig: boolea behaviourclassname: Strig CotextServer(it,Strig) fialize():void stop():void start():void <<Java Iterface>> IServerBehaviour iitialize(socket):void behaviour():void start():void TemplateServerThread clietsocket: Socket TemplateServerThread() ru():void WebServerBehaviour WebServerBehaviour() iitialize(socket):void behaviour():void httperror(it,dataoutputstream):void sedheader(strig,file,dataoutputstream):void filetype(file):strig sedfile(file,dataoutputstream):void WebServerDemo starts the http server public class WebServerDemo { public static void mai(strig[] args) throws Exceptio { it sport = 2000; ew CotextServer(sport,"WebServerBehaviour ).start();

23 WebServerBehaviour import java.io.*; import java.et.*; class WebServerBehaviour exteds TemplateServerThread { public void iitialize (Socket clietsocket) { this.clietsocket = clietsocket; Webserver (http server): behaviour public void behaviour() throws Exceptio { DataOutputStream writecliet = ew DataOutputStream (clietsocket.getoutputstream()); BufferedReader readcliet = ew BufferedReader(ew IputStreamReader(clietSocket.getIputStream())); fial char URLseparator = '/'; Strig webbase = "." + URLseparator + "src"; //./src (Eclispe) Strig httpheader = ""; Strig clietrequest; Strig servername = "WebServerDemo 1.0";

24 Webserver (http server): behaviour // Parse HTTP request clietrequest = readcliet.readlie().touppercase(); Strig delims = "[ ]+"; //spaces Strig[] tokes = clietrequest.split(delims); Strig cmd = tokes[0]; //HTTP Commad - GET, POST Strig page = tokes[1]; //Page ame Strig versio = tokes[2]; //HTTP Versio // Skip request lies after GET commad // (stop after lie sequece CRLF ou LF ou ull) do { clietrequest = readcliet.readlie(); while (!clietrequest.equals("") &&!clietrequest.equals("\r\") &&!clietrequest.equals("\") ); Webserver (http server): behaviour // Sed page to cliet oly if HTTP COMMAND is GET // other commads are igored if (cmd.equals("get")) { Strig filename = webbase; if (page.charat(0)!= URLseparator) filename += URLseparator; filename += page; if (page.cotais("..")) httperror(403, writecliet); else if (page.cotais("//")) httperror(403, writecliet); else { //Ope page file File f = ew File(fileName); if (!f.exists()) httperror(404, writecliet); else { //sed header to cliet sedheader(servername, f, writecliet); sedfile(f, writecliet); URL: :2000/folder/p

25 Webserver (http server): behaviour //Close I/O streams writecliet.close(); readcliet.close(); //Ed behaviour Auxiliary fuctios private void httperror(it error, DataOutputStream writecliet) throws IOExceptio { Strig html = "HTTP/1.0 "; switch(error) { case 400: html += "400 Bad Request"; break; case 403: html += "403 Forbidde"; break; case 404: html += "404 Not Foud"; break; //... HTTP/ Forbidde html += "\r\\r\"; writecliet.writebytes(html);

26 Auxiliary fuctios private void sedheader(strig servername, File f, DataOutputStream writecliet) throws IOExceptio { Strig header = "HTTP/ OK\r\ ; header += "Coectio: close\r\"; //we ca't hadle //persistet coectios header += servername+"\r\"; header += filetype(f); header += "Cotet-legth: "+f.legth()+"\r\"; // This blak lie marks the ed of the httpheader // ad the start of the body header += "\r\"; writecliet.writebytes(header); HTTP/ OK Coectio: close WebServerDemo 1.0 Cotet-Type: text/html Cotet-legth: Auxiliary fuctios private Strig filetype(file f){ Strig filename = f.getabsolutepath().tolowercase(); Strig type = "Cotet-Type: ; //other extesios are assumed text if (filename.edswith(".zip")) type += "applicatio/x-zip-compressed"; else if (filename.edswith(".gif")) type += "image/gif"; else if (filename.edswith(".jpg") filename.edswith(".jpeg")) type += "image/jpeg"; else if (filename.edswith(".ico")) type+= "image/x-ico"; //plety more types to fill i... else type += "text/html"; retur type += "\r\";

27 Auxiliary fuctios private void sedfile(file f, DataOutputStream writecliet) throws IOExceptio{ FileIputStream fis = ew FileIputStream(f); while (true) { it b = fis.read(); if (b == -1) break; //ed of file writecliet.write(b); fis.close(); //Ed class Testig the webserver, a idex.html file for <html> <head> <title>demo java web server </title> </head> <body> POO 2016/2017 <br> A todos umas férias com muita class! <br> <IMG src="duke_christmas.pg" alt= Bom Natal!"/> </body> </html> 27

28 Check poit: Test the webserver 28