服務端：

public class Server {
    public static void main(String [ ] args){
        try {
            //1、建立服務端
            ServerSocket serverSocket = new ServerSocket(8888);
            System.out.println("-------服務器等待客戶端鏈接--------");

            //2、啟動服務端
            Socket socket = serverSocket.accept();
            System.out.println("客戶端"+ socket.getInetAddress().getHostAddress()+"鏈接成功");

            //3、獲取輸入流,讀取客戶端信息
            InputStream inputStream = socket.getInputStream();//獲取輸入流
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);//將字節流轉換字符流
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);//為字符流建立緩沖區
            String line = null;
            while ((line = bufferedReader.readLine()) != null){
                System.out.println(line);
            }
            socket.shutdownInput();

            //4、獲取輸出流，響應客戶端
            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream);
            printWriter.write("歡迎你！");
            printWriter.flush();
            socket.shutdownOutput();

            //5、關閉相關資源
            socket.close();
            serverSocket.close();

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

客戶端

public class Client {
    public static void main(String [] args){
        try {
            //1、創建客戶端socket，指定服務器地址和端口號
            Socket socket = new Socket("localhost",8888);

            //2、獲取輸出流，向服務器發送信息
            OutputStream outputStream = socket.getOutputStream();//字節流
            PrintWriter printWriter = new PrintWriter(outputStream);//將字節流包裝為打印流
            printWriter.write("用戶名：123; 密碼：123");
            printWriter.flush();
            socket.shutdownOutput();

            //3、獲取輸入流，讀取客戶端響應的消息
            InputStream inputStream = socket.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream);
            BufferedReader bufferedReader = new BufferedReader(inputStreamReader);
            String line = null;
            while((line = bufferedReader.readLine()) != null){
                System.out.println(line);
            }
            socket.shutdownInput();

            //4、關閉資源
            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}