urllib.request.urlopenでJSONをPOSTする例

import json
import urllib.error
import urllib.request

try:
    data = json.dumps({'key':'value'}).encode()
    headers = {'Content-Type': 'application/json'}
    req = urllib.request.Request(
        "http://localhost:8000/",
        data=data,
        headers=headers,
        method="POST"
        )
    with urllib.request.urlopen(req) as resp:
        print(resp.status)
        print(resp.headers)
        print(resp.read())
except urllib.error.HTTPError as e:
    print("HTTPError", e)
    print(e.status)
    print(e.headers)
    print(e.read())
except urllib.error.URLError as e:
    print("URLError", e)
    print(e.reason)
except e:
    print(e)