Regaining the basics of Java (20): Summary of network communication

Regain the basics of java (20): Summary of network communication

1. The concept of network

1. By at least two Computers are connected through some transmission media 2. Local area network Internet 3. Advantages of the network

2. Software technology architecture

1. B/S Various websites Browser/Server 2. C/S QQ 360 WPS Various APPs Client/Server 3. Comparison a. Later installation and maintenance B/S is more convenient C/S is slightly more troublesome b. User operation is convenient and the customer experience C/S is slightly stronger c. Three development waves Computer popularization Internet (PC) Early stage: C/S Later: B/S Mobile Internet (mobile terminal) C/S

##3. Principles of network communication

1. Three elements IP address: Locate a certain computer in the network TCP/IP protocol: Regulations How to transmit data Router: Hardware Addressing and routing 2. Delivering express 3. 127.0.0.1 is a special The IP address represents the local IP address when there is no network. It is generally used for testing and debugging

4. Port

1. IP address It can only guarantee that the data is sent to a certain computer, so which program is responsible for receiving it is distinguished by the port 2. We need to set a port number (room number) for each networked program 3. 0-65535 Port numbers in the range of 0-1024 are generally reserved or occupied by the system 4. IP+port number

5. TCP/IP protocol

1. Type: TCP protocol UDP protocol 2. Difference 3. A program can have either TCP protocol or UDP protocol

6. Java network programming API structure

java.net package InetAddress class, used to represent or store computer IP address 192.168.0.7 The String type cannot be used to store --------------------UDP protocol--- ---------------DatagramPacket class, used to represent the message class of encapsulated data DatagramSocket class, used to represent the Socket of one end of sending and receiving data Similar to the transceiver of a mobile phone end-to-end point-to-point- ------------------TCP protocol-----------------ServerSocket class, used to represent the server-side Socket Socket class, Used to represent client Socket C/SSocket. Original meaning: socket. Translated in programming language as: socket. Similar to mobile phone transceiver

7. InetAddress class

1. Represent or store IP address cannot be new

8. UDP network programming

1. DatagramPacket class, datagram This It is the format of packaged data

2. DatagramSocket class, transceiver (mobile phone)

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