WebSocket

Echo 处理函数可以通过升级底层 HTTP 连接来提供 WebSocket 连接。此示例展示两种方式：标准的 golang.org/x/net/websocket 包，以及流行的 gorilla/websocket 库。

使用 net WebSocket

服务器

package main

import (
  "context"
  "fmt"

  "github.com/labstack/echo/v5"
  "github.com/labstack/echo/v5/middleware"
  "golang.org/x/net/websocket"
)

func hello(c *echo.Context) error {
  websocket.Handler(func(ws *websocket.Conn) {
    defer ws.Close()
    for {
      // Write
      if err := websocket.Message.Send(ws, "Hello, Client!"); err != nil {
        c.Logger().Error("failed to write WS message", "error", err)
      }

      // Read
      msg := ""
      if err := websocket.Message.Receive(ws, &msg); err != nil {
        c.Logger().Error("failed to write WS message", "error", err)
      }
      fmt.Printf("%s\n", msg)
    }
  }).ServeHTTP(c.Response(), c.Request())
  return nil
}

func main() {
  e := echo.New()

  e.Use(middleware.RequestLogger())
  e.Use(middleware.Recover())

  e.Static("/", "../public")
  e.GET("/ws", hello)

  sc := echo.StartConfig{Address: ":1323"}
  if err := sc.Start(context.Background(), e); err != nil {
    e.Logger.Error("failed to start server", "error", err)
  }
}

使用 gorilla WebSocket

服务器

package main

import (
  "context"
  "fmt"

  "github.com/gorilla/websocket"
  "github.com/labstack/echo/v5"
  "github.com/labstack/echo/v5/middleware"
)

var (
  upgrader = websocket.Upgrader{}
)

func hello(c *echo.Context) error {
  ws, err := upgrader.Upgrade(c.Response(), c.Request(), nil)
  if err != nil {
    return err
  }
  defer ws.Close()

  for {
    // Write
    err := ws.WriteMessage(websocket.TextMessage, []byte("Hello, Client!"))
    if err != nil {
      c.Logger().Error("failed to write WS message", "error", err)
    }

    // Read
    _, msg, err := ws.ReadMessage()
    if err != nil {
      c.Logger().Error("failed to read WS message", "error", err)
    }
    fmt.Printf("%s\n", msg)
  }
}

func main() {
  e := echo.New()

  e.Use(middleware.RequestLogger())
  e.Use(middleware.Recover())

  e.Static("/", "../public")

  e.GET("/ws", hello)

  sc := echo.StartConfig{Address: ":1323"}
  if err := sc.Start(context.Background(), e); err != nil {
    e.Logger.Error("failed to start server", "error", err)
  }
}

客户端

<!doctype html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <title>WebSocket</title>
</head>

<body>
  <p id="output"></p>

  <script>
    var loc = window.location;
    var uri = 'ws:';

    if (loc.protocol === 'https:') {
      uri = 'wss:';
    }
    uri += '//' + loc.host;
    uri += loc.pathname + 'ws';

    ws = new WebSocket(uri)

    ws.onopen = function() {
      console.log('Connected')
    }

    ws.onmessage = function(evt) {
      var out = document.getElementById('output');
      out.innerHTML += evt.data + '<br>';
    }

    setInterval(function() {
      ws.send('Hello, Server!');
    }, 1000);
  </script>
</body>

</html>

输出

服务器

Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!

客户端

Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!