Question

please help. About java tcp.

this is what i have so far. how to convert input value into ASCII sequence For example the message: “Hello World” would become “Ifmmp!Xpsme”For example the message: “Hello World” would become “Ifmmp!Xpsme”in server.java.

Client.java:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;
import java.net.SocketTimeoutException;

public class Client {
public static void main(String[] args) throws IOException {
  
Socket client = new Socket("127.0.0.1", 20006);
client.setSoTimeout(10000);
  
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

PrintStream out = new PrintStream(client.getOutputStream());
  
BufferedReader buf = new BufferedReader(new InputStreamReader(client.getInputStream()));
boolean flag = true;
while(flag){
System.out.print("Enter：");
String str = input.readLine();
  
out.println(str);
if("bye".equals(str)){
flag = false;
}else{
try{
  
String echo = buf.readLine();
System.out.println(echo);
}catch(SocketTimeoutException e){
System.out.println("Time out, No response");
}
}
}
input.close();
if(client != null){

client.close();
}
}
}

server.java:

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;

public class ServerThread implements Runnable {

private Socket client = null;
public ServerThread(Socket client){
this.client = client;
}

@Override
public void run() {
try{

PrintStream out = new PrintStream(client.getOutputStream());

BufferedReader buf = new BufferedReader(new InputStreamReader(client.getInputStream()));
boolean flag =true;
while(flag){
  
String str = buf.readLine();
//how to convert input value into ASCII sequence For example the message: “Hello World” would become “Ifmmp!Xpsme”For example the message: “Hello World” would become “Ifmmp!Xpsme”
out.println("echo:" + str);
}
}
}
out.close();
client.close();
}catch(Exception e){
e.printStackTrace();
}
}

}

Answer 1

//ServerThread.java

import java.net.*;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;

public class ServerThread implements Runnable
{

   private Socket client = null;

  
   public ServerThread(Socket client)
   {
       this.client = client;
       //this should run the thread
       this.run();
   }
   //function that converts string to ascii sequence
   public String formatToAscii(String str)
   {
       //according to the example given
       //Hello world will become Ifmmp!Xpsme --> your just incrementing the value of each char by one
       //H + 1 -> I,   e + 1 -> f,....
       //so this pattern can be achieved using java string function charAt(pos) gives a char at specified position.
       //it is clear that the incremented char has no bounds, just incrementing is enough
       //because space( ) + 1 -> ! Space ascii is 32 and ! ascii is 33
       //so just increment the ascii value by 1
       //and hence update all chars like this way
       //
       int i;
       String res = "";
       for(i = 0;i<str.length();i++)
       {
           res +=((char)(str.charAt(i) + 1));
       }
       return res;
   }
   @Override
   public void run()
   {
       try
       {

           PrintStream out = new PrintStream(client.getOutputStream());

           BufferedReader buf = new BufferedReader(new InputStreamReader(client.getInputStream()));
           boolean flag =true;
           while(flag)
           {
          
               String str = buf.readLine();
               //when client sends bye set flag to false
               //so it will break the infinite loop
               if(str.equals("bye"))
               {
                   System.out.println("echo:" + str);
                   flag = false;
               }
               else
               {
                   //if not
                   //convert the msg to ascii sequence by calling formatToAscii
                   str = formatToAscii(str);
                   out.println("echo:" + str);
               }
           }
           out.close();
           client.close();
       }
      
       catch(Exception e)
       {
           e.printStackTrace();
       }
   }
   public static void main(String[] args)
   {
       //you haven't created a server socket
       //without it server wont create
       //below is the server socket creation code
       try
       {
           ServerSocket ss = new ServerSocket(1433);
           System.out.println("Server is waiting");
           //accpts a client
           Socket sa = ss.accept();
           System.out.println("Connected with client "+sa.getInetAddress());
           //creates a client ServerThread object
           ServerThread ob = new ServerThread(sa);
          
           ss.close();
       }
       catch(Exception e)
       {
          
       }
   }
}

//Client.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;
import java.net.SocketTimeoutException;

public class Client
{
   public static void main(String[] args) throws IOException
   {
      
       Socket client = new Socket("127.0.0.1", 1433);
       client.setSoTimeout(10000);
      
      
       BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

       PrintStream out = new PrintStream(client.getOutputStream());
      
       BufferedReader buf = new BufferedReader(new InputStreamReader(client.getInputStream()));
       boolean flag = true;
       while(flag)
       {
           System.out.print("Enter: ");
           String str = input.readLine();
          
           out.println(str);
           if("bye".equals(str))
           {
               flag = false;
           }
           else
           {
               try
               {
                   String echo = buf.readLine();
                   System.out.println(echo);
               }
               catch(SocketTimeoutException e)
               {
                   System.out.println("Time out, No response");
               }
           }
       }
       input.close();
       if(client != null)
       {
           client.close();
       }
   }
}
//sample output