Java tcp ip protocol multiple communication problems with

  java   tcp   socket   communication

with TCP / IP protocol client and server communication , where the server did not write , write-only client ,
protocol requirements are as follows :
1. Send "Connect" command, the server returns the "DATA RECEIVE PASSWORD"
2. Send password " 01234567 " , the server returns "CONNECT OK!"

I wrote a client to achieve a TCP / IP connection established by DataOutputStream input stream , while the character data into a byte in output in the console , but as a second step, not know how, after sending the password , the server can not return to respond , do not know what went wrong , please enlighten , source code is as follows :

  import java.net.*;
  import java.io.*;
  
  public class ByteClient {
  
  	private int clientNumber;  
      private SocketAddress address;  
      public ByteClient(int clientNum) {  
          clientNumber = clientNum;  
      }  
  	public void setupClients(String serverHostName, int port) throws IOException {  
  	        address = new InetSocketAddress(serverHostName, port);  
  	            System.out.println();  
  	            System.out.println("start client No. 1");  
  	            Socket socket = new Socket();  
  	            socket.connect(address);  
  	          //ADD
  	            byte[] hello = "Connect".getBytes(); 
  	            byte[] helloreturn="DATA RECEIVE PASSWORD...".getBytes();
  	            byte[] code="01234567".getBytes();
  	           
                      DataOutputStream dos = new DataOutputStream(socket.getOutputStream());  
  	            dos.write(hello, 0, hello.length);
  	            DataInputStream bufferedReader = new DataInputStream(socket.getInputStream());  
  	            byte[] cbuff = new byte[256];  
  	            char[] charBuff = new char[256]; 
  	            int size = 0;  
  
  	            //ADD 判断是否接收到DATA RECIEVE PASSWORD
  	            while( (size = bufferedReader.read(cbuff))> 0) {  
  	                convertByteToChar(cbuff, charBuff, size);  
  	                System.out.println(charBuff);//Console中显示了已收到的数据"DATA RECIEVE PASSWORD
  	            }
  	                //ADD
  	            dos.write(code,0,code.length);//重复以上收发过程，怎么没有结果？
  	            while( (size = bufferedReader.read(cbuff))> 0) {  
  	                convertByteToChar(cbuff, charBuff, size);  
  	                System.out.println(charBuff);
  	              //ADD END
  	            }  
             
  	           // bufferedReader.close();  
  	            //socket.close();  
  	        }  
  	   
  	
  	private void convertByteToChar(byte[] cbuff, char[] charBuff, int size) {  
          for(int i=0; i<charBuff.length; i++) {  
              if(i < size) {  
                  charBuff[i] = (char)cbuff[i];  
              } else {  
                  charBuff[i] = ' ';  
              }  
          }  
            
      }
  	 
  	public static void main(String[] args) throws IOException {
  		// TODO Auto-generated method stub
  			try{
  			ByteClient client = new ByteClient(4);  
              client.setupClients("XXX.XXX.XXX.XXX", 9999);//端口号和IP为服务器端IP，在此未列出
              
  		}
  		catch (IOException e) {  
              e.printStackTrace();  
          }  
  		}
  	}
  

------ Solution ------------------------------------- -------
Socket 's InputSream is blocking , when you read it it would have been stuck there until the Socket closed or flow off.
So your program has been stuck in line 30
while ((size = bufferedReader.read (cbuff))> 0)

Incidentally that convertByteToChar method approach is not good , why not just use the built-in decoding method String , and you the only support ASCII character sets , such as if there is Chinese characters how to do ?
------ Solution ---------------------------------------- ----
Socket general practice is to use two threads , one to read, one to write and other control
Or you can use non-blocking SocketChannel
------ For reference only ------------------------- --------------

If you want to achieve the second step that I mentioned , what should be achieved? Create a socket?


Thank you, I try
------ For reference only ---------------------------- -----------

Results posted after the discovery, the problem is still not resolved, multi-threaded implementation is a server-side solution , but I can only do this program designed client , multi-threaded client how to deal with ?