Learn network programming functions in Go language and implement WebSocket communication

Learn the network programming functions in Go language and implement WebSocket communication

Introduction
Go language, as a powerful programming language, is widely used in the field of network programming. It provides a wealth of network programming functions and libraries, allowing developers to easily implement various network communication functions. This article will introduce some commonly used network programming functions in the Go language and combine examples to implement WebSocket communication.

1. Network programming function

1. net.Listen
   Function signature: func Listen(network, address string) (Listener, error)
   Purpose: Listen to the specified network address and return a Listener object
   Example:

   listener, err := net.Listen("tcp", "127.0.0.1:8080")
   if err != nil {
    log.Fatal(err)
   }
   defer listener.Close()

2. Accept
   Function signature: func (l *TCPListener) Accept() (Conn, error)
   Purpose: Accept the connection request and return a Conn object
   Example:

   conn, err := listener.Accept()
   if err != nil {
    log.Fatal(err)
   }
   defer conn.Close()

3. WebSocket protocol
   WebSocket is a protocol for full-duplex communication on a single TCP connection. Allows real-time communication between client and server. The Go language provides the gorilla/websocket library to easily implement WebSocket communication functions.

2. Implement WebSocket communication

1. Install gorilla/websocketLibrary
   Execute the following command in the command line:

   go get -u github.com/gorilla/websocket

2. Server-side code

   package main
   
   import (
    "log"
    "net/http"
   
    "github.com/gorilla/websocket"
   )
   
   var upgrader = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
   }
   
   func websocketHandler(w http.ResponseWriter, r *http.Request) {
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()
   
    for {
        messageType, message, err := conn.ReadMessage()
        if err != nil {
            log.Println(err)
            break
        }
        log.Printf("Received message: %s
   ", message)
   
        if err := conn.WriteMessage(messageType, message); err != nil {
            log.Println(err)
            break
        }
    }
   }
   
   func main() {
    http.HandleFunc("/websocket", websocketHandler)
    log.Fatal(http.ListenAndServe(":8080", nil))
   }

3. Client-side code

   package main
   
   import (
    "log"
    "net/url"
   
    "github.com/gorilla/websocket"
   )
   
   func main() {
    u := url.URL{Scheme: "ws", Host: "localhost:8080", Path: "/websocket"}
    conn, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()
   
    for i := 0; i < 5; i++ {
        message := []byte("Hello from client")
        if err := conn.WriteMessage(websocket.TextMessage, message); err != nil {
            log.Fatal(err)
        }
   
        _, receivedMessage, err := conn.ReadMessage()
        if err != nil {
            log.Fatal(err)
        }
        log.Printf("Received message from server: %s", receivedMessage)
    }
   }

Run the above two code files, This enables communication between the client and the server based on the WebSocket protocol. The client will send a message to the server, receive the message back from the server, and repeat 5 times.

Summary
This article introduces some commonly used network programming functions in the Go language, and implements WebSocket communication with examples. By learning this knowledge, we can better understand and apply it to actual network programming. Whether we are developing web applications or other network communication scenarios, mastering these network programming functions will greatly improve our development efficiency. It is hoped that readers can further understand the network programming features of Go language through learning, so that they can be flexibly applied in actual projects.

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