go---get, postForm

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "net/http"
    "net/http/cookiejar"
    "net/url"
    "strconv"
    "time"

    // 略去
)

// GetSheet .
func GetSheet(start, end time.Time) ([]byte, error) {
    cookieJar, _ := cookiejar.New(nil)

    client := &http.Client{
        Jar: cookieJar,
    }

    _, err := client.Get("http://10.10.10.10/login/")
    if err != nil {
        return nil, err
    }

    _, err = client.PostForm("http://10.10.10.10/login/", url.Values{
        "username":  {"aa},
        "password":  {"bb"},
        "logintype": {"user"},
    })
    if err != nil {
        return nil, err
    }

    sheetQuery := url.Values{
        "startDate":      {start.Format("2006-01-02")},
        "endDate":        {end.Format("2006-01-02")},
    }

    result, err := client.Get("http://10.10.10.10/login/original_records/?" + sheetQuery.Encode())
    if err != nil {
        return nil, err
    }

    b, err := ioutil.ReadAll(result.Body)
    if err != nil {
        return nil, err
    }

    result.Body.Close()
    return b, nil
}

参考
https://www.cnblogs.com/jackylee92/p/6214591.html