Server.java

package heimaufgaben;
import java.io.*;
import java.lang.*;
import java.net.*;
import java.nio.*;
import java.security.*;
import java.util.*;
import java.text.*;

public class Server{
  //ähnlich wie beimclient now:
  private String ip = ""; 
  private int port = 0;
  private ServerSocket serverSocket;
  private BufferedReader reader;
  private BufferedWriter writer;
  private ArrayList<String> historyList = new ArrayList<String>();

    public Server() throws IOException
    {
      BufferedReader portinput = new BufferedReader(new InputStreamReader(System.in));
      System.out.print("Serverport: ");
      String givenPort = portinput.readLine();
      portinput.close();
      
      try {
        port = Integer.parseInt(givenPort);
        if (port < 1 || port > 65535) {
          System.err.println("Err der angegebene Port ist ungültig (muss zwischen 1 und 65535 liegen)");
          return; 
        }
    
      } catch (NumberFormatException e) {
        System.err.println("Err Format des Eingegebenen Ports ist Falsch");
        return; 
      }
      
            //PROBLEM -> reads from wrong socket so stalemate
            serverSocket = new ServerSocket(port);
            //Socket socket = new Socket(); old code

            System.out.println("Server has created Socket ready to accept client");
            Socket socket = serverSocket.accept();
            System.out.println("Server has accepted Connection");
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            
            
            String command = "";
            while (true) {
              // Warte auf eine Nachricht vom Client:
              while(command == ""){
              command = reader.readLine();
              }
              // Verarbeite den Befehl:
              try {
                String[] words = command.split(" "); 
                
                switch (words[0].toLowerCase())
                {
                  case "ping":
                  historyList.add(command);
                  PingPong();
                  command ="";
                  break;

                  case "echo":
                  historyList.add(command);
                  Echo(command);
                  command ="";
                  break;
                  
                  case "current":
                    switch(words[1].toLowerCase())
                    {
                        case "time":
                        historyList.add(command);
                        sendTime(words[1]);
                        command ="";
                        break;
                      
                        case "date":
                        historyList.add(command);
                        sendTime(words[1]);
                        command ="";
                        break;
                      
                        default:
                        historyList.add(command);
                        writer.write(words[0] + "Err Unsuported Format!\n");
                        writer.flush();
                        command ="";
                        break;
                    }
                  case "history":
                  historyList.add(command);
                  History();
                  command ="";
                  break;

                  case "close":
                  
                  break;



                  default:
                    writer.write("Err Wrong or No command\n");
                    System.out.println("Err Wrong or No command");
                    writer.flush();
                    break;    
                }
            
              } catch (IOException Re) {
                System.err.println("Error with commands");
              }
            }

        }

    private void History()
    {
      try{
        for(int i = 0;i < historyList.size();i++)
        {
          writer.write(i + ": " + historyList.get(i));
          
        }
        writer.write("HstrLstDone");
        writer.flush();
      }catch (IOException err)
      {
        System.err.println("History Error");
      } 
    }


    private void sendTime(String format) throws IOException
      {
      try{
        switch(format.toLowerCase())
        {
        
          case("time"):
            SimpleDateFormat timeDateFormat = new SimpleDateFormat("hh:mm:ss");
            String formatedStringTime = timeDateFormat.format(new Date());
            writer.write(format.toUpperCase()+" "+formatedStringTime+"\n");
            writer.flush();
            break;

          case("date"):
            
            SimpleDateFormat dateDateFormat = new SimpleDateFormat("dd.MM.yyyy");
            String formatedStringDate = dateDateFormat.format(new Date());
            writer.write(format.toUpperCase()+" "+formatedStringDate+"\n");
            writer.flush();
            break;

          default:
         writer.write("Unknown Format Requested: Known Formats are: Date || Time");
         break;          

        }
      }catch (IOException err)
      {
        System.err.println("ServerErr sendTime");
      }
    }
    
  
    private void Echo(String msg) throws IOException
    {
      try{  
        System.out.println("received and sending back: " +msg);
        writer.write(msg+"\n");
        writer.flush();
        return;
      }catch (IOException err)
      {
        System.err.println("ServerErr Echo");
      }
    }

    

    private void PingPong() throws IOException {
      try {
        // Sende "Pong" an den Client:
        System.out.println("received: PING sending: PONG");
        writer.write("PONG\n");
        writer.flush();
        
        return;
      } catch (IOException e) {
        System.err.println("Problem bei void PingPong() (IOException)");
        return;
      }
    }

    
  
    public static void main(String[] args)
    {
      System.out.println("Hello World!");
    }
}