java网络编程

IP地址的代表类是InetAddress

客户端 发送端

public class clinet {
    public static void main(String[] args) throws Exception {
        byte[] buffer = "我来了！".getBytes();
        //1、创建待发送的数据包
        DatagramPacket packet = new DatagramPacket(buffer,buffer.length, InetAddress.getLocalHost(),8888);
        //2、创建发送对象
        DatagramSocket socket = new DatagramSocket();
        //3、发送数据包
        socket.send(packet);
        //4、关闭连接
        socket.close();
    }
}

服务端 接收端

public class server {
    public static void main(String[] args) throws Exception {
        //1、创建接收的数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer,buffer.length);
        
        //2、创建接收对象
        DatagramSocket socket = new DatagramSocket(8888);
        
        //3、接收数据包
        socket.receive(packet);
        
        //4、获取发送方的端口和ip
        int port=packet.getPort();
        InetAddress ip = packet.getAddress();

        //5、关闭连接
        int len = packet.getLength();
        String rs = new String(buffer,0,len);
        System.out.println("来自"+ip+":"+port+"的信息："+rs);
        socket.close();
    }
}

客户端

public class clinet {
    public static void main(String[] args) throws Exception {
        //1 创建socket对象
        Socket socket = new Socket("127.0.0.1",9999);
        //2 从管道获取一个字节输出流
        OutputStream os = socket.getOutputStream();
        //3 把输出流包装为打印流
        PrintStream ps = new PrintStream(os);
        //4 发送消息
        ps.println("hhh");
        ps.flush();
    }
}

服务端

public class server {
    public static void main(String[] args) throws Exception {
        //1 注册端口号
        ServerSocket s = new ServerSocket(9999);
        //2 等待客户端的连接请求,建立socket管道
        Socket socket = s.accept();
        //3 从socket管道得到字节输入流
        InputStream is = socket.getInputStream();
        //4 把字节流包装为输入缓冲字符流
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        //5 打印结果
        String msg;
        if((msg=br.readLine())!=null){
            System.out.println(socket.getRemoteSocketAddress()+msg);
        }
    }
}