## WebSocket
### 使用 `net` 库的 WebSocket
#### 服务端
`server.go`
```go
package main
import (
"fmt"
"log"
"github.com/labstack/echo"
"github.com/labstack/echo/middleware"
"golang.org/x/net/websocket"
)
func hello(c echo.Context) error {
websocket.Handler(func(ws *websocket.Conn) {
defer ws.Close()
for {
// Write
err := websocket.Message.Send(ws, "Hello, Client!")
if err != nil {
log.Fatal(err)
}
// Read
msg := ""
err = websocket.Message.Receive(ws, &msg)
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", msg)
}
}).ServeHTTP(c.Response(), c.Request())
return nil
}
func main() {
e := echo.New()
e.Use(middleware.Logger())
e.Use(middleware.Recover())
e.Static("/", "../public")
e.GET("/ws", hello)
e.Logger.Fatal(e.Start(":1323"))
}
```
### 使用 `gorilla` 的 WebSocket
#### 服务端
`server.go`
```go
package main
import (
"fmt"
"log"
"github.com/labstack/echo"
"github.com/gorilla/websocket"
"github.com/labstack/echo/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 {
log.Fatal(err)
}
// Read
_, msg, err := ws.ReadMessage()
if err != nil {
log.Fatal(err)
}
fmt.Printf("%s\n", msg)
}
}
func main() {
e := echo.New()
e.Use(middleware.Logger())
e.Use(middleware.Recover())
e.Static("/", "../public")
e.GET("/ws", hello)
e.Logger.Fatal(e.Start(":1323"))
}
```
### 客户端
`index.html`
```html
<!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>
```
### 输出示例
`Client`
```sh
Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!
Hello, Client!
```
`Server`
```sh
Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!
Hello, Server!
```
