def get_domain(url):
    spltAr = url.split("://")
    i = (0,1)[len(spltAr)>1]
    dm = spltAr[i].split("?")[0].split('/')[0].split(':')[0].lower()
    #print(dm)
    return dm

def get_domain_without_prefix(url):
    spltAr = url.split("://")
    i = (0,1)[len(spltAr)>1]
    dm = spltAr[i].split("?")[0].split('/')[0].split(':')[0].lower()

    if("www." in dm):
        dm = dm.replace("www.", "")

    #print(dm)
    return dm

urls = [
    "http://www.oreilly.com/people/adam-michael-wood",
    "https://javabeat.net/introduction-to-hibernate-caching/",
]

for url in urls:
    domain = get_domain_without_prefix(url)
    print(domain)

oreilly.com
javabeat.net