java网络编程

1. ip、域名、端口

• InetAddress 封装计算机的ip和域名

  • 获得对象

    ​ - InetAddress.getLocalHost();

    ​ - InetAddress.getByName(String host); //参数host可以是 ip地址/域名

    ​ - InetAddress.getByAddress([String host,]byte[] addr)

  • getHostName() //获取主机名

  • getHostAddress() //获取ip

  • getAddress() //获取byte[] 类型的ip

  //获取本机的InetAdress实例
  InetAddress address=InetAddress.getLocalHost();
  System.out.println(address);
  System.out.println("计算机名："+address.getHostName());
  System.out.println("IP地址："+address.getHostAddress());
  byte[] bytes=address.getAddress();//字节数组形式的ip
  System.out.println("字节数组形式的ip:"+Arrays.toString(bytes));
  

• InetSocketAddress 在InetSocketAddress的基础上封装了端口

  • 创建对象

    InetSocketAddress address=new InetSocketAddress(InetAddress addr,int port)

    InetSocketAddress address=new InetSocketAddress(String host,int port)

  • 获取主机名、ip、端口

  InetAddress iAddress=InetAddress.getLocalHost();
  InetSocketAddress iSAddress=new InetSocketAddress(iAddress,5418);
  System.out.println(iSAddress);
  	//iSAddress.getAddress();同上
  System.out.println("主机名:"+iSAddress.getHostName());
  	//isAddress.getAddress().getHostName(); 同上
  System.out.println("ip:"+iSAddress.getAddress().getHostAddress());
  System.out.println("端口:"+iSAddress.getPort());
  

  2.URL

  			URL url=new URL("http://news.sohu.com/index.html#a?name=ndy");
  			System.out.println("协议："+url.getProtocol());
  			System.out.println("域名:"+url.getHost());
  			System.out.println("端口:"+url.getPort());
  			System.out.println("默认端口:"+url.getDefaultPort());
  			
  			System.out.println("资源:"+url.getFile());
  			System.out.println("相对路径资源:"+url.getPath());
  			System.out.println("锚点:"+url.getRef());
  			System.out.println("参数:"+url.getQuery());//返回参数,若有锚点返回null
  			
  

  3.UDP: DatagramSocket、 DatagramPacket

  • DatagramPacket常用方法
    • 客户端 DatagramPacket(byte buf[], int length, SocketAddress address)
    • 服务端 DatagramPacket(byte buf[], int length)
    • ​ (get|set) (Address|Data|Length|Offset|Port|SocketAddress)

  //客户端	
  		//1.创建客户端
  		DatagramSocket socket=new DatagramSocket(1452);
  		//2.准备byte[]数据
  		String msg="那好";
  		byte[] data=msg.getBytes();
  		//3.封装数据
  		DatagramPacket packet =new DatagramPacket(data, data.length,new 						InetSocketAddress("localhost",5418));
  		//4.发送数据
  		socket.send(packet);
  		//5.关闭资源
  		socket.close();
  //服务端
  		//1.创建服务端
  		DatagramSocket socket=new DatagramSocket(5418);
  		//2.准备接受数据的容器
  		byte[] container=new byte[1024];
  		//3.封装成包
  		DatagramPacket packet=new DatagramPacket(container, container.length);
  		//4.接收
  		socket.receive(packet);
  		//5.分析-解包
  		byte[] data=packet.getData();
  		int length=packet.getLength();
  		System.out.println(new String(data,0,length));
  		//6.关闭资源
  		socket.close();
  

  4.TCP: ServerSocket 、Socket

//服务端
		//1.创建ServerSocket
		ServerSocket server=new ServerSocket(8888); 
		//2.接收客户端连接	server.accept()
		Socket socket=server.accept();
		//System.out.println("一个客户端建立连接");
		//3发送数据| 接收数据 socket.getOutputStream()|socket.getInputStream
		String msg="青山隐隐水迢迢";
		BufferedWriter bw=new BufferedWriter(
				new OutputStreamWriter(
					socket.getOutputStream()
				)
			);
		bw.write(msg);
		bw.newLine();
		bw.flush();
//客户端
		//1、创建客户端，指定服务器和端口
		Socket client=new Socket("localhost",8888);
		//Socket client=new Socket();client.connent(SocketAddress);同上
		//2、接收数据
		BufferedReader br=new BufferedReader(
				new InputStreamReader(client.getInputStream())
				);
		String echo=br.readLine();
		System.out.println(echo);
		br.close();