// getLocalHost 获取本机的IP地址对象/** InetAddress address = InetAddress.getLocalHost();* System.out.println("IP地址："+address.getHostAddress());* System.out.println("主机名："+address.getHostName());*/// 获取别人机器的IP地址对象。// 可以根据一个IP地址的字符串形式或者是一个主机名生成一个IP地址对象。InetAddress address = InetAddress.getByName("YIFAN");System.out.println("IP地址：" + address.getHostAddress());System.out.println("主机名：" + address.getHostName());

public class Demo1Sender {public static void main(String[] args) throws IOException {// 建立udp的服务DatagramSocket datagramSocket = new DatagramSocket();// 准备数据，把数据封装到数据包中。String data = "这个是我第一个udp的例子..";// 创建了一个数据包DatagramPacket packet = new DatagramPacket(data.getBytes(),data.getBytes().length, InetAddress.getLocalHost(), 9090);// 调用udp的服务发送数据包datagramSocket.send(packet);// 关闭资源 ---实际上就是释放占用的端口号datagramSocket.close();}
}

public class Demo1Receive {public static void main(String[] args) throws IOException {// 建立udp的服务 ，并且要监听一个端口。DatagramSocket socket = new DatagramSocket(9090);// 准备空的数据包用于存放数据。byte[] buf = new byte[1024];DatagramPacket datagramPacket = new DatagramPacket(buf, buf.length); // 1024// 调用udp的服务接收数据socket.receive(datagramPacket); // receive是一个阻塞型的方法，没有接收到数据包之前会一直等待。// 数据实际上就是存储到了byte的自己数组中了。System.out.println("接收端接收到的数据："+ new String(buf, 0, datagramPacket.getLength()));  // getLength()// 获取数据包存储了几个字节。// 关闭资源socket.close();}}

public class SafeReceive {public static void main(String[] args) throws IOException, Exception {//建立udp的服务DatagramSocket socket = new DatagramSocket(9090);//建立空的数据包存储数据byte[] buf = new byte[1024];DatagramPacket packet = new DatagramPacket(buf, buf.length);//不断接收数据包while(true){socket.receive(packet);System.out.println(new String(buf,0,packet.getLength()));Thread.sleep(10);}}
}

public class Demo1Clinet {public static void main(String[] args) throws IOException{//建立tcp的服务Socket socket  = new Socket(InetAddress.getLocalHost(),9090);//获取到Socket的输出流对象OutputStream outputStream = socket.getOutputStream();//利用输出流对象把数据写出即可。outputStream.write("服务端你好".getBytes());//获取到输入流对象，读取服务端回送的数据。InputStream inputStream = socket.getInputStream();byte[] buf = new byte[1024];int length = inputStream.read(buf);System.out.println("客户端接收到的数据："+ new String(buf,0,length));//关闭资源socket.close();        }
}

//服务端
public class Demo1Server {public static void main(String[] args) throws Exception {//建立Tcp的服务端,并且监听一个端口。ServerSocket serverSocket = new ServerSocket(9090);//接受客户端的连接Socket socket  =  serverSocket.accept(); //accept()  接受客户端的连接 该方法也是一个阻塞型的方法，没有客户端与其连接时，会一直等待下去。//获取输入流对象，读取客户端发送的内容。InputStream inputStream = socket.getInputStream();byte[] buf = new byte[1024];int length = 0;length = inputStream.read(buf);System.out.println("服务端接收："+ new String(buf,0,length));//获取socket输出流对象，想客户端发送数据OutputStream outputStream = socket.getOutputStream();outputStream.write("客户端你好啊！".getBytes());//关闭资源serverSocket.close();}}