On network programming in Java

On network programming in java

1. Basic

Network programming means programs written to run on a plurality of devices (computers) of these devices are connected through a network.

In java provides the java.net package contains classes and interfaces. They provide low-level communication details. We can use these classes and interfaces to specifically address the problem.

Three cornerstones of the Internet: url html http

Provides support for two common network protocol package java.net:

UDP:. Acronym User Datagram Protocol non-connection-oriented, unsafe protocol is simple, small overhead, high efficiency, limited size, usually less than 60k

TCP: connection-oriented, safe, low efficiency based on 3-way handshake: 1. Dial 2. In response, the data transmission connection 3

2.UDP

1.UDP basic processes: sending end

Use DatagramSocket designated port, create the sender

Preparing data must be converted into a byte array

Encapsulated package DatagramPacket

Transmitting wrapping send (DatagramPacket p)

Release resources

Example 1 transmitting end:

        import java.net.DatagramPacket;
        import java.net.DatagramSocket;
        import java.net.InetSocketAddress;
        public class UDPSend1 {
        	public static void main(String[] args) throws Exception {
        		System.out.println("发送方启动中...");
        		// 1.使用DatagramSocket指定端口,创建发送端
        		DatagramSocket client = new DatagramSocket(6666);
        		// 2.准备数据 一定要转成字节数组
        		String data = "落霞与孤鹜齐飞,秋水共长天一色";
        		byte[] datas = data.getBytes();
        		// 3.封装成DatagramPacket包裹
        		DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 8888));
        		// 4.发送包裹send(DatagramPacket p)
        		client.send(packet);
        		// 5.释放资源
        		client.close();
        	}
        }
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2.UDP basic processes: a receiving end

Use DatagramSocket designated port, create the receiving end

Ready containers, packages wrapped into DatagramPacket

Blocking receive packages receive (DatagramPacket p)

analyze data

Release resources

Example 1 a receiving end:

        import java.net.DatagramPacket;
        import java.net.DatagramSocket;
        public class UDPReceive1 {
    	public static void main(String[] args) throws Exception {
    		System.out.println("接收端准备中.... ");
    		// 1.使用DatagramSocket指定端口,创建接收端
    		DatagramSocket server = new DatagramSocket(8888);
    		// 2.准备容器,封装成DatagramPacket包裹
    		byte[] container = new byte[1024 * 60];
    		DatagramPacket packet = new DatagramPacket(container, 0, container.length);
    		// 3.阻塞式接收包裹receive(DatagramPacket p)
    		server.receive(packet);
    		// 4.分析数据
    		byte[] datas = packet.getData();
    		int len = packet.getLength();
    		System.out.println(new String(datas, 0, len));
    		// 5.释放资源
    		server.close();
    	}
    }
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3.TCP

1.TCP basic process: Client

Custom Client Socket Socket (String host, int port) to create a stream socket to the specified port number on the specified host

Prepare data

Write IO operation

Release resources

Client Example 2:

        import java.io.DataOutputStream;
        import java.io.IOException;
        import java.net.Socket;
        import java.net.UnknownHostException;
        public class Client01 {
    	public static void main(String[] args) throws UnknownHostException, IOException {
    		System.out.println("-------------Client-----------");
    		//1.定义客户端 Socket  Socket(String host, int port)
    		Socket client=new Socket("127.0.0.1",7777);
    		//2.准备数据
    		String str="name=zhangsan&pwd=123";
    		//3.写出  直接从管道中获取流
    		DataOutputStream data=new DataOutputStream(client.getOutputStream());
    		data.writeUTF(str);
    		data.flush();
    		//4.关闭
    		data.close();
    		client.close();
    	}
    }
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2.TCP basic processes: the server

Defined server ServerSocket ServerSocket (int port) Creates a server socket bound to the specified port

Blocking monitor Socket accept ()

Monitor connection socket and accept it

io operations

Release resources

Server Example 2:

    import java.io.DataInputStream;
    import java.io.IOException;
    import java.net.ServerSocket;
    import java.net.Socket;
    public class Server01 {
    	public static void main(String[] args) throws IOException {
    		System.out.println("-------------Server-----------");
    		//1.定义服务端
    		ServerSocket server=new ServerSocket(7777);
    		//2.阻塞式监听  Socket accept() 
    		Socket client=server.accept();
    		//3.io操作,直接从管道中获得流
    		DataInputStream in=new DataInputStream( client.getInputStream());
    		String str=in.readUTF();
    		System.out.println(str);
    		//4.释放资源
    		in.close();
    		client.close();
    		server.close();
    	}
    }	
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