json.load(fp, *, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)

json.loads(s, *, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)

import json

print("Started Reading JSON file")
with open("developer.json", "r") as read_file:
    print("Converting JSON encoded data into Python dictionary")
    developer = json.load(read_file)

    print("Decoded JSON Data From File")
    for key, value in developer.items():
        print(key, ":", value)
    print("Done reading json file")

import json

print("Started Reading JSON file")
with open("./demo.json", "r") as read_file:
    print("Converting JSON encoded data into Python dictionary")
    developer = json.load(read_file)

    print("Decoding JSON Data From File")
    print("Printing JSON values using key")
    print(developer["name"])
    print(developer["salary"])
    print(developer["email"])
    print("Done reading json file")

import json
developerJsonString = """
{ 
    "name": "imango", 
    "salary": 1, 
    "skills": [ "python", "Machine Learning", "java" ], 
    "email": "imango@hh.com", 
    "projects": [ "write", "read" ] } 
    """
print("Started converting JSON string document to Python dictionary")
developerDict = json.loads(developerJsonString)
print("Printing key and value")
print(developerDict["name"])
print(developerDict["salary"])
print(developerDict["skills"])
print(developerDict["email"])
print(developerDict["projects"])
print("Done converting JSON string document to a dictionary")

developerInfo ="""{
    “id"：20，
    “name"：“imango"，
    “salary"：1，
    “email"：“ imango@hh.com"，
    “experience"：{“python"：5，“ data Science"：2}，
    “projectinfo"：[{“id"：100，“ name"：“ai"}]
}
"""

import json

print("Started reading nested JSON array")
developerDict = json.loads(developerInfo)

print("Project name: ", developerDict["projectinfo"][0]["name"])
print("Experience: ", developerDict["experience"]["python"])

print("Done reading nested JSON Array")

import json
from collections import OrderedDict

print("Ordering keys")
OrderedData = json.loads('{"John":1, "Emma": 2, "Ault": 3, "Brian": 4}', object_pairs_hook=OrderedDict)
print("Type: ", type((OrderedData)))
print(OrderedData)
————————————————输出————————————
OrderedDict([('John', 1), ('Emma', 2), ('Ault', 3), ('Brian', 4)])

如何在json.load()中使用parse_float和parse_int

正如我已经告诉parse_float 和parse_int，这两个参数都是可选参数，但是，如果指定了参数，将使用每个要解码的JSON浮点数和整数的字符串进行调用。默认情况下，这等效于float(num_str)和int(num_str)。

假设JSON文档包含许多浮点值，并且您想将所有浮点值舍入到两个小数点。在这种情况下，我们需要定义一个自定义函数来执行您想要的任何舍入。我们可以将这样的函数传递给parse_float kwarg。

另外，如果您想对整数值执行任何运算，我们可以编写一个自定义函数并将其传递给parse_int kwarg。例如，您在JSON文档中收到了请假天，并且您想要计算要扣除的薪水。

本地json文件内容如下：
{
“salary"：1300.56565，
"leavedays":2
}

import json

def roundFloats(salary):
    return round(float(salary), 2)

def salartToDeduct(leaveDays):
    salaryPerDay = 465
    return int(leaveDays) * salaryPerDay

print("Load float and int values from JSON and manipulate it")
print("Started Reading ")
with open("./demo.json", "r") as read_file:
    developer = json.load(read_file, parse_float=roundFloats,
                          parse_int=salartToDeduct)
    # after parse_float
    print("Salary: ", developer["salary"])

    # after parse_int
    print("Salary to deduct: ", developer["leavedays"])
    print("Done reading ")


________输出如下——————————
Started Reading 
Salary: 1300.55
Salary to deduct: 930
Done reading 

使用json.load()实现自定义JSON解码器

Python的内置json模块只能处理具有直接JSON等效项的Python基本类型(例如，字典，列表，字符串，数字，None等)。

当执行json.loador json.loads()方法时，它将返回一个Python字典。如果要将JSON转换为自定义Python对象，则可以编写一个自定义JSON解码器并将其传递给该json.loads()方法，以便获得自定义Class对象而不是字典。

让我们看看如何在load方法中使用JSON解码器。在此示例中，我们将看到如何使用object_hook 加载方法的参数。

import json
from collections import namedtuple
from json import JSONEncoder

def movieJsonDecod(movieDict):
    return namedtuple('X', movieDict.keys())(*movieDict.values())

# class for your reference
class Movie:
    def __init__(self, name, year, income):
        self.name = name
        self.year = year
        self.income = income

# Suppose you have this json document.
movieJson = """{
    "name": "Interstellar",
    "year": 2014,
    "income": 7000000
}"""

# Parse JSON into an Movie object
movieObj = json.loads(movieJson, object_hook=movieJsonDecod)
print("After Converting JSON into Movie Object")
print(movieObj.name, movieObj.year, movieObj.income)

——>>>>>本章节到此完成