Java Sockets not using J2EE
Hi,
As an outline I am in the early stages of trying to set up an IM client. I'm just in the process of trying to send more than one message via a socket from client to server and get the same message come back out to the client using just J2SE (client outline).
I can get the first message to go to the server and be spat out from the client but if I try a second message the program hangs.
I'm sure it is to do with the way the socket is formed. I did originally have a close socket command in the client program which forced me to rerun the client for every message whilst the server program worked happily in the background.
I have now removed the close command so that I could send more than one message without having to rerun the client but the server doesn't even receive it.
Any advice please?
Client
import java.io.*;
import java.net.*;
import javax.swing.*;
import java.util.StringTokenizer;
publicclass HTTPClient{
String host, path, username;
int port;
Socket s;
publicstaticvoid main (String argv[]){
//I've added this statement to the original skeleton code for those
//who are unsure of how to run the program.
if (argv.length != 1){
System.out.println("usage: java HTTPClient host:port/filepath");
System.exit(1);
}
//creates a new HTTPClient, where argv[0] is the URL.
new HTTPClient(argv[0]);
}
public HTTPClient(String url){
try{
//gets url
URL myURL =new URL(url);
//gets host
host = myURL.getHost();
//gets port
port = myURL.getPort();
if (port == -1) port = 80;;
//gets path to file
path = myURL.getPath();
//appends a / to path if no path exists
if (path.equals("")) path ="/";
s =new Socket(InetAddress.getByName(host), port);
username = JOptionPane.showInputDialog(null,"Please enter your username");
String password ="";
for(int i = username.length()-1; i >= 0; i--)//password = username backwards
{
char ch = username.charAt(i);
password += ch;
}
String password_attempt ="";//set string as empty
int count = 0;//count number of pasword attempts
while(!password_attempt.equals(password)){
password_attempt = JOptionPane.showInputDialog(null,"Please enter your password ");
count++;//increment count
if (count == 3){//if 3 tries then print error message and close program
JOptionPane.showMessageDialog(null,
"You have enter a password incorrectly 3 times",
"Login Error",
JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
}
sendRequest(s.getOutputStream());
}
catch(MalformedURLException murl){
System.out.println("Badly formatted URL " + murl.getMessage());
}
catch(IOException e){
System.out.println("Problem initialising socket " + e.getMessage());
}
}
publicvoid sendRequest(OutputStream out){
String message_out;
message_out = JOptionPane.showInputDialog(null,"Please enter a message");
message_out +="\r\n\r\n";
try{
out.write(message_out.getBytes("US-ASCII"));
out.flush();
printResponse(s.getInputStream());//gets response from server
}
catch (IOException e){System.out.println(e.getMessage());
}
}
/*The basis of this method is to read in the input from the server and print
*it to the screen. It sleeps for 500 milliseconds in case the server is
*busy then starts to read in characters then prints them to screen.*/
publicvoid printResponse(InputStream in){
try{
while (in.available() <= 0)
Thread.sleep(500);
while (in.available() > 0)
System.out.print((char) in.read());
System.out.println ("");
sendRequest(s.getOutputStream());//gets a new request for the server
}
catch (IOException e){
System.out.println(e.getMessage());
}
catch (InterruptedException ie){
System.out.println("Error waiting for response " + ie.getMessage());
}
}
}
and the Server
import java.io.*;
import java.net.*;
import java.util.*;
publicclass ProjectServer{
String message_in, message_out;
publicstaticvoid main(String argv[]){
//I've added this statement for those that may be unfamiliar of how to run
//the program.
if (argv.length != 1){
System.out.println("usage: java HTTPServer port");
System.exit(1);
}
//creates a new HTTPSever, argv[0] is the port.
new ProjectServer(Integer.parseInt(argv[0]));
}
public ProjectServer(int port){
boolean listening =true;
//Socket's must be created in a try and catch block as they may generate
//exceptions, which the program must deal with.
try{
ServerSocket ss =new ServerSocket(port);
System.out.println("HTTP Server running and listening for requests...");
while (listening){
Socket mySocket = ss.accept();
//create an InputStream called 'in'
InputStream in = mySocket.getInputStream();
//pass 'in' to the readInput method
readInput(in);
//create an OutputStream called 'out'
OutputStream out = mySocket.getOutputStream();
message_out = message_in;
System.out.println("I'm here");
//transform 'response' into bytes ready for output
out.write(message_out.getBytes("US-ASCII"));
//flush data out of socket
out.flush();
//close socket
//mySocket.close();
}
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
privatevoid readInput(InputStream in){
System.out.println("Hiya!!!!");
message_in ="";
int ch;
StringBuffer sbuf =new StringBuffer();
try{
//while there is something to read
while ((ch = in.read()) != -1){
//if current character is a \r...
if (ch =='\r'){
//read next character
ch = in.read();
//if next character is a \n....
if (ch =='\n'){
//if buffer length is 0 then \r\n\r\n has been received
//so break out of while loop
if (sbuf.length() == 0)
break;
//if buffer length > 0 add buffer contents to vector
message_in += sbuf.toString();
//set buffer length to 0
sbuf.setLength(0);
}
}
//if character wasn't a \r then append character to the buffer
else sbuf.append((char)ch);
}
}
catch (Exception e){
System.out.println(e.getMessage());
}
}
}
Kind regards,
Chris
