Java TCP套接字编程

import java.io.*;
import java.net.*;

class TCP Client {
public static void main(String argv[ ]) throws Exception
{
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(newInputStreamReader(ClientSocket.getInputStream()));

sentence = inFromUser.readLine();

outToServer.writeBytes(sentence + '\n');

modifiedSentence = inFromServer.readLine();

System.out.println("FROM Server: " + modifiedSentence);

ClientSocket.close();
}
}

import java.io.*;
import java.net.*;

class TCP Server {

public static void main(String argv[]) throws Exception
{
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);
}
}
}