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How to use Go and http.Transport to limit the number of request attempts?
When writing network requests in Go language, sometimes we need to retry the request multiple times to increase the success rate of the request. Using http.Transport and some simple code, we can easily implement a limit on the number of request attempts.
First, we need to import the net/http
and net/url
packages. Then, we create a custom http.Transport object and set its maximum number of attempts. The code is as follows:
package main import ( "fmt" "net/http" "net/url" ) // 自定义Transport type RetryTransport struct { Transport http.Transport Retries int } // 实现RoundTrip方法 func (rt *RetryTransport) RoundTrip(request *http.Request) (*http.Response, error) { var ( resp *http.Response err error ) for i := 0; i < rt.Retries; i++ { resp, err = rt.Transport.RoundTrip(request) if err == nil { // 请求成功,直接返回 return resp, nil } } return nil, fmt.Errorf("maximum retries reached") } func main() { // 创建自定义Transport,并设置最大尝试次数为3次 rt := &RetryTransport{ Transport: http.Transport{}, Retries: 3, } client := http.Client{ Transport: rt, } // 构造请求 url := "https://example.com" request, _ := http.NewRequest(http.MethodGet, url, nil) // 发送请求,并获取响应 response, err := client.Do(request) if err != nil { fmt.Println("Error:", err) return } defer response.Body.Close() // 输出响应的内容 body, _ := ioutil.ReadAll(response.Body) fmt.Println(string(body)) }
In the above code, we define a RetryTransport
structure, which contains a http.Transport
object and a Retries
field, used to record the maximum number of attempts. We also implement the RoundTrip
method, which will be called when the request is initiated. In this method, we use a loop to try multiple requests until the maximum number of attempts is reached or the request succeeds.
In the main
function, we create a custom RetryTransport
object and assign it to http.Client
#Transport field. Then, we use
http.NewRequest to construct a request, and use
client.Do to initiate the request and get the response. Finally, we print the contents of the response.
RetryTransport object according to our needs and configure it as needed.
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