Problema compilazione socket java

[isal]

Salve a tutti,

non riesco a capire perchè eseguendo questi due programmi con Eclipse:

Server

import java.io.*; import java.net.*; public class TCPServer { /* * Ricopio la classe esempio sulle slide di Reti di Calcolatori (Socket TCP, server) * */ public static void main(String[] args) throws Exception{ // TODO Auto-generated method stub String clientSentence; String capitalizedSentence; ServerSocket welcomeSocket = new ServerSocket(6789); while(true){ Socket connectionSocket= welcomeSocket.accept(); BufferedReader inFromClient=new BufferedReader(new InputStreamReader(connectionSocket.getInputStream())); DataOutputStream outToClient =new DataOutputStream(connectionSocket.getOutputStream()); clientSentence= inFromClient.readLine(); capitalizedSentence= clientSentence.toUpperCase()+'\n'; outToClient.writeBytes(capitalizedSentence); connectionSocket.close(); } } }

Client

import java.io.*; import java.net.*; public class TCPClient { public static void main(String argv[])throws Exception { // TODO Auto-generated method stub String sentence; String modifiedSentence; BufferedReader inFromUser= new BufferedReader(new InputStreamReader((System.in))); Socket clientSocket =new Socket("hostname", 6789); DataOutputStream outToServer=new DataOutputStream(clientSocket.getOutputStream()); BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); sentence = inFromUser.readLine(); outToServer.writeBytes(sentence + '\n'); modifiedSentence= inFromServer.readLine(); System.out.println("FROM SERVER: " + modifiedSentence ); clientSocket.close(); } }

mi vengono dati i seguenti errori:

per il server

Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at TCPServer.main(TCPServer.java:16)

per il client

Exception in thread "main" java.net.UnknownHostException: hostname
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at TCPClient.main(TCPClient.java:14)

Chi può aiutarmi, per favore? Ringrazio in anticipo chi risponderà

[isal]

Potrebbe essere un problema legato alla configurazione sbagliata di eclipse per lo sviluppo di applicazioni client sever?

[isal]

Nessuno mi sa rispondere?

[Alex'87]

Originariamente inviato da isal
Salve a tutti,

non riesco a capire perchè eseguendo questi due programmi con Eclipse:

Server

import java.io.*; import java.net.*; public class TCPServer { /* * Ricopio la classe esempio sulle slide di Reti di Calcolatori (Socket TCP, server) * */ public static void main(String[] args) throws Exception{ // TODO Auto-generated method stub String clientSentence; String capitalizedSentence; ServerSocket welcomeSocket = new ServerSocket(6789); while(true){ Socket connectionSocket= welcomeSocket.accept(); BufferedReader inFromClient=new BufferedReader(new InputStreamReader(connectionSocket.getInputStream())); DataOutputStream outToClient =new DataOutputStream(connectionSocket.getOutputStream()); clientSentence= inFromClient.readLine(); capitalizedSentence= clientSentence.toUpperCase()+'\n'; outToClient.writeBytes(capitalizedSentence); connectionSocket.close(); } } }

Client

import java.io.*; import java.net.*; public class TCPClient { public static void main(String argv[])throws Exception { // TODO Auto-generated method stub String sentence; String modifiedSentence; BufferedReader inFromUser= new BufferedReader(new InputStreamReader((System.in))); Socket clientSocket =new Socket("hostname", 6789); DataOutputStream outToServer=new DataOutputStream(clientSocket.getOutputStream()); BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); sentence = inFromUser.readLine(); outToServer.writeBytes(sentence + '\n'); modifiedSentence= inFromServer.readLine(); System.out.println("FROM SERVER: " + modifiedSentence ); clientSocket.close(); } }

mi vengono dati i seguenti errori:

per il server

Exception in thread "main" java.net.BindException: Address already in use: JVM_Bind
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.PlainSocketImpl.bind(Unknown Source)
at java.net.ServerSocket.bind(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at java.net.ServerSocket.<init>(Unknown Source)
at TCPServer.main(TCPServer.java:16)

per il client

Exception in thread "main" java.net.UnknownHostException: hostname
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at TCPClient.main(TCPClient.java:14)

Chi può aiutarmi, per favore? Ringrazio in anticipo chi risponderà

Per quel che riguarda il server sembra che tu lo abbia avviato più volte. La prima volta va a buon fine, le volte successive da problemi perché la nuova istanza trova la porta occupata.

Nel caso del client, "hostname" come nome dell'host non va bene, probabilmente è stato messo solo come segnaposto. Se sei in locale dovresti risolvere usando localhost

ps: la prossima volta scrivi il tag CODE a mano, usando il pulsantino il codice viene spappolato su un'unica riga