在由@jruizaranguren链接的github issue的基础上，我得到了如下代码，它按预期工作：

import os
import json
import jsonschema

schema_dir = os.path.abspath('resources')
with open(os.path.join(schema_dir, 'schema.json')) as file_object:
    schema = json.load(file_object)

# Your data
data = {"sample": "woo!"}

# Note that the second parameter does nothing.
resolver = jsonschema.RefResolver('file://' + schema_dir + '/', None)

# This will find the correct validator and instantiate it using the resolver.
# Requires that your schema contains a line like this: "$schema": "http://json-schema.org/draft-04/schema#"
jsonschema.validate(data, schema, resolver=resolver)