客户端

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;

public class SocketClient {

    public static void main(String[] args) {
        Socket socket = null;

        try {

            socket = new Socket("localhost", 8888);

            DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
            DataInputStream dis = new DataInputStream(socket.getInputStream());

            dos.writeUTF( "我是客户端，请求连接");
            System.out.print(dis.readUTF());

            socket.close();

        }catch (UnknownHostException e){

                e.printStackTrace();

        }catch (IOException e){

            e.printStackTrace();
        }
    }
}

服务端

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class SocketServer {
    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(8888);
            Socket socket = serverSocket.accept();
            DataOutputStream dos = new DataOutputStream(socket.getOutputStream());
            DataInputStream dis = new DataInputStream(socket.getInputStream());
            System.out.print("服务器收到客户端的来链接请求"+ dis
                    .readUTF());
            dos.writeUTF("接受连接请求成功！");
            socket.close();
            serverSocket.close();

        }catch (
                IOException e){
            e.printStackTrace();
        }
    }
}