GoLang 中的简易 WebSocket 服务器

实时应用程序最有效的策略之一是使用 WebSocket 协议。

WebSocket 是一种计算机通信协议，通过单个传输控制协议（TCP）连接提供同步双向通信通道。为了实现兼容性，WebSocket 握手使用 HTTP Upgrade header[3] 从 HTTP 协议转换到 WebSocket 协议。

虽然完全可以将连接从基本的 net/http 连接处理程序升级为 WebSocket 风格连接，但我们将使用 gorilla/websocket Go 模块。通过 Go 模块，我们只需几行简单的 Go 代码就能创建 WebSocket 服务器。

第一步：安装 gorilla/websocket 模块

go get github.com/gorilla/websocket

第二步：创建 HTTP 端点

package main

import (
  "net/http"
  "github.com/gorilla/websocket"
  "fmt"
)

func main() {
  mux := http.NewServeMux()
  mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
    // HTTP Handler for localhost:8080/ws
  })
  fmt.Println("Server Started Successfully")
  if err := http.ListenAndServe("localhost:8080", mux); err != nil {
    panic(err)
  }
}

第三步：升级连接

package main

import (
  "net/http"
  "github.com/gorilla/websocket"
  "fmt"
)

// Create a connection upgrader
var upgrader websocket.Upgrader = websocket.Upgrader{}

func main() {
  mux := http.NewServeMux()
  mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
      conn, err := upgrader.Upgrade(w, r, nil)
      if err != nil {
        panic(err)
      }
      // Defer Closing the connection
      defer conn.Close()
      // ...
  })
  fmt.Println("Server Started Successfully")
  if err := http.ListenAndServe("localhost:8080", mux); err != nil {
    panic(err)
  }
}

第四步：使用 for 循环捕捉信息

// This section is the same file as above, just shortened to our handler
mux.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
      panic(err)
    }
    // Defer Closing the connection
    defer conn.Close()
    // Use a for loop to catch incoming messages.
    for {
        // msgType = int msg type
        // p = incoming message as []byte
        // err = error on message
        msgType, p, err := conn.ReadMessage()
        if err != nil {
          fmt.Println("Error reading message")
          return
        }
        // Once we recieve a message, we can echo it back.
        err = conn.WriteMessage(msgType, p)
        if err != nil {
          fmt.Println("Error sending message reply")
          return
        }
    }
})

第五步：（可选）测试 /w Postman