Golang : read gzipped http response
There are times when we want to grab a website content for parsing(crawling) and found out that the content is gzipped.
Normally, to deal with gzipped HTML reply, you can use Exec package to execute curl
from command line and pipe the gzipped content to gunzip, such as this :
curl -H "Accept-Encoding: gzip" http://www.thestar.com.my | gunzip
Another way to process gzipped http response can be done in Golang as well. The following codes will demonstrate how to get same result as the curl
command via Golang.
package main
import (
"compress/gzip"
"fmt"
"io"
"net/http"
"os"
)
func main() {
client := new(http.Client)
request, err := http.NewRequest("Get", " http://www.thestar.com.my", nil)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
request.Header.Add("Accept-Encoding", "gzip")
response, err := client.Do(request)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
defer response.Body.Close()
// Check that the server actual sent compressed data
var reader io.ReadCloser
switch response.Header.Get("Content-Encoding") {
case "gzip":
reader, err = gzip.NewReader(response.Body)
if err != nil {
fmt.Println(err)
os.Exit(1)
}
defer reader.Close()
default:
reader = response.Body
}
// to standard output
_, err = io.Copy(os.Stdout, reader)
// see https://www.socketloop.com/tutorials/golang-saving-and-reading-file-with-gob
// on how to save to file
if err != nil {
fmt.Println(err)
os.Exit(1)
}
}
References :
http://golang.org/pkg/os/exec/
http://golang.org/pkg/net/http/#Get
https://www.socketloop.com/tutorials/how-to-check-with-curl-if-my-website-or-the-asset-is-gzipped
By Adam Ng
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