业务上有时候需要服务器向客户端返回二进制字节,如1个像素的gif图片(前端通过image标签访问,1像素保证其不可见)。
示例:
客户端请求URL: http://www.example.com:8080/cms.gif?ck1=ABCD&ck2=CFGAA,根据参数ck1,ck2的取值执行业务逻辑,完成后向前端返回一个1个像素的gif图片.
package main
import (
"fmt"
"io/ioutil"
"net/http"
)
var gBytes []byte
//业务逻辑部分
func save(ck1 string, ck2 string) {
fmt.Printf("ck1=%s ck2=%s\n", ck1, ck2)
}
func handler(w http.ResponseWriter, r *http.Request) {
query := r.URL.Query()
ck1 := query.Get("ck1")
ck2 := query.Get("ck2")
save(ck1, ck2)
w.Header().Add("Content-Type", "image/gif")
w.WriteHeader(200)
n, err := w.Write(gBytes)
if err != nil {
fmt.Printf("n=%d err:%v\n", n, err)
}
}
func main() {
bytes, err := ioutil.ReadFile("./cms.gif")
if err != nil {
fmt.Printf("fail to read cms.gif:%v\n", err)
}
gBytes = bytes
http.HandleFunc("/cms.gif", handler)
http.ListenAndServe(":8080", nil)
}