http.Get Examples: Download Web PagesUse the net http package to download web pages. Specify http.Get, Body and Status.
Http.Get. Golang can be used to download web pages. This helps with validating a site works correctly (or for trying to get important data from the web page).
With the net http package, we have many helpful funcs for accessing files through HTTP. We do not need to write any low-level code to do this.
Http.Get example. Let us begin with this example program that uses http.Get. Please note we must import the "net/http" package at the top.
Detail We use the Get() func to download the home page of Wikipedia—the HTTPS protocol is used here.
Detail We require that the Body (a stream) is entirely closed before continuing. The defer keyword waits for the Body to close.
Detail We use the ioutil package to access the ReadAll method—this func is useful in many Go programs.
package main import ( "fmt" "io/ioutil" "net/http" ) func main() { // Get Wikipedia home page. resp, _ := http.Get("https://en.wikipedia.org/") // Defer close the response Body. defer resp.Body.Close() // Read everything from Body. body, _ := ioutil.ReadAll(resp.Body) // Convert body bytes to string. bodyText := string(body) fmt.Println("DONE") fmt.Println("Response length: ", len(bodyText)) // Convert to rune slice to take substring. runeSlice := []rune(bodyText) fmt.Println("First chars: ", string(runeSlice[0:10])) }
DONE Response length: 73727 First chars: <!DOCTYPE
Status. When a HTTP request is made, the response includes a status code. We can access the string containing the status with "Status."
And We can access the int code itself with StatusCode. This is probably easier to use when testing for a 404 error.
Tip When using http.Get(), a 404 error is not returned as an error in Go. It is returned as a successful download with a 404 code.
package main import ( "fmt" "net/http" "strings" ) func main() { // This file does not exist. resp, _ := http.Get("https://www.dotnetperls.com/robots.txt") defer resp.Body.Close() // Test status string. fmt.Println("Status:", resp.Status) if strings.Contains(resp.Status, "404") { fmt.Println("Is not found (string tested)") } // Test status code of the response. fmt.Println("Status code:", resp.StatusCode) if resp.StatusCode == 404 { fmt.Println("Is not found (int tested)") } }
Status: 404 Not Found Is not found (string tested) Status code: 404 Is not found (int tested)
Serve. With the ListenAndServe func, also part of the http module, we can build a simple web server in Golang. Each response can have a special function with HandleFunc.
A review. Making sure your website is working correctly is an important job. And Golang is well-suited to download pages and validate them.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
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