Golang : Get and Set User-Agent examples
Problem :
You want to detect User-Agent of your web application users and also setup your own User-Agent name for your Golang application.
How to get and set User-Agent in Golang application?
Solution :
Example 1 :
package main
import (
"fmt"
"net/http"
)
func getUserAgent(w http.ResponseWriter, r *http.Request) {
ua := r.Header.Get("User-Agent")
fmt.Printf("user agent is: %s \n", ua)
w.Write([]byte("user agent is " + ua))
}
func main() {
http.HandleFunc("/", getUserAgent)
http.ListenAndServe(":8080", nil)
}
Example 2:
package main
import (
"fmt"
"net/http"
)
func getUserAgent(w http.ResponseWriter, r *http.Request) {
ua := r.UserAgent() //<---- simpler and faster!
fmt.Printf("user agent is: %s \n", ua)
w.Write([]byte("user agent is " + ua))
}
func main() {
http.HandleFunc("/", getUserAgent)
http.ListenAndServe(":8080", nil)
}
To set User-Agent for your Golang application, first create a client and set client's request header with [your user-agent name] before executing the request.
For instance :
client := &http.Client{}
request, err := http.NewRequest("GET", "http://example.com", nil)
if err != nil {
log.Fatalln(err)
}
request.Header.Set("User-Agent", "[your user-agent name]")
resp, err := client.Do(req)
The web site example.com will detect your program User-Agent as whatever name you choose for [your user-agent name].
Reference :
By Adam Ng
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