單執行緒伺服器端：

package socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;

public class MyServer {
	public static void main(String[] args) throws IOException {
		ServerSocket server = new ServerSocket(5678);
		Socket client = server.accept();
		BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
		PrintWriter out = new PrintWriter(client.getOutputStream());
		while (true) {
			String str = in.readLine();
			System.out.println(str);
			out.println("has receive....");
			out.flush();
			if (str.equals("end"))
				break;
		}
		client.close();
	}
}
 

package client;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;

public class MyClient {
	static Socket server;

	public static void main(String[] args) throws Exception {
		server = new Socket(InetAddress.getLocalHost(), 5678);
		BufferedReader in = new BufferedReader(new InputStreamReader(server.getInputStream()));
		PrintWriter out = new PrintWriter(server.getOutputStream());
		BufferedReader wt = new BufferedReader(new InputStreamReader(System.in));
		while (true) {
			String str = wt.readLine();
			out.println(str);
			out.flush();
			if (str.equals("end")) {
				break;
			}
			System.out.println(in.readLine());
		}
		server.close();
	}
}