## 流式響應
- 當數據產生的時候發送數據
- 使用分塊傳輸編碼（Chunked transfer encoding）的流式 JOSN 響應。
### Server
`server.go`
```go
package main
import (
"net/http"
"time"
"encoding/json"
"github.com/labstack/echo"
)
type (
Geolocation struct {
Altitude float64
Latitude float64
Longitude float64
}
)
var (
locations = []Geolocation{
{-97, 37.819929, -122.478255},
{1899, 39.096849, -120.032351},
{2619, 37.865101, -119.538329},
{42, 33.812092, -117.918974},
{15, 37.77493, -122.419416},
}
)
func main() {
e := echo.New()
e.GET("/", func(c echo.Context) error {
c.Response().Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSON)
c.Response().WriteHeader(http.StatusOK)
for _, l := range locations {
if err := json.NewEncoder(c.Response()).Encode(l); err != nil {
return err
}
c.Response().Flush()
time.Sleep(1 * time.Second)
}
return nil
})
e.Logger.Fatal(e.Start(":1323"))
}
```
### 客戶端
```sh
$ curl localhost:1323
```
### 輸出
```sh
{"Altitude":-97,"Latitude":37.819929,"Longitude":-122.478255}
{"Altitude":1899,"Latitude":39.096849,"Longitude":-120.032351}
{"Altitude":2619,"Latitude":37.865101,"Longitude":-119.538329}
{"Altitude":42,"Latitude":33.812092,"Longitude":-117.918974}
{"Altitude":15,"Latitude":37.77493,"Longitude":-122.419416}
```
