21 网络编程

1 Url UrlConnection

public static void main(String[] args) throws Exception
	{
		URL url=new URL("Http://www.baidu.com");
		URLConnection connection=url.openConnection();
		
		
		InputStream iStream =connection.getInputStream();
		OutputStream outputStream=new FileOutputStream("D:/baidu.html");
		int length=0;
		byte [] buffer=new byte[1024];
		
		while(length!=-1)
			
		{
			length=iStream.read(buffer,0,buffer.length);
			outputStream.write(buffer);
			
			
		}
		outputStream.close();
		iStream.close();
	}

2 InetAddress

InetAddress address=InetAddress.getLocalHost();
	
	System.out.println(address);
	
	address=InetAddress.getByName("WWW.baidu.com");
	
	System.out.println(address);
}

3 套接字

Socket是连接运行在网络上的两个程序间的双向通讯的端点

1) 建立Socket连接
2) 获得输入/输出流
3）读/写数据
4) 关闭输入/输出流
5) 关闭Socket

ServerSocket serverSocket=new ServerSocket(50116);
		
		Socket listnerSocket=serverSocket.accept();
		
		System.out.println("服务器消息：有人连接了");
		
		InputStream inputStream=listnerSocket.getInputStream();
		byte []buffer=new byte[1024];
		inputStream.read(buffer);
		
		System.out.println("客户端消息："+new String(buffer));
		
		OutputStream outputStream=listnerSocket.getOutputStream();
		
	outputStream.write("Welcome".getBytes());
			
		outputStream.close();
		inputStream.close();
		listnerSocket.close();

Socket socket=new Socket("127.0.0.1",50116);
		
		OutputStream outputStream=socket.getOutputStream();
		
		outputStream.write("hello".getBytes());
		
		InputStream inputStream=socket.getInputStream();
		
		byte [] reader=new byte[1024];
		inputStream.read(reader);
		
		System.out.println("服务器消息："+new String(reader));
		
		
		outputStream.close();
		inputStream.close();
		socket.close();

4 UDP

DatagramSocket socket=new DatagramSocket();
		
		byte[] data="bingjia i miss you".getBytes();
		DatagramPacket packet=new DatagramPacket(data, data.length,
				InetAddress.getByName("127.0.0.1"),50116);
		
		socket.send(packet);
		
		byte [] dataReceiver=new byte[10000];
		DatagramPacket  packetReceive=new DatagramPacket(dataReceiver,10000);
		socket.receive(packetReceive);
		
		System.out.println(new String(dataReceiver,0,packetReceive.getLength())+"  Port"+packetReceive.getPort());

DatagramSocket socket=new DatagramSocket(50116);
		byte [] dataReceiver=new byte[10000];
		DatagramPacket  packetReceive=new DatagramPacket(dataReceiver,10000);
		socket.receive(packetReceive);
		
		System.out.println(new String(dataReceiver,0,packetReceive.getLength())+"  Port"+packetReceive.getPort());

		byte[] data="hehe".getBytes();
		DatagramPacket packet=new DatagramPacket(data, data.length,
				packetReceive.getAddress(),packetReceive.getPort());
		
		socket.send(packet);