python 修改json的值

做工程时遇到需要监听json文件，根据json文件中的key-value值作出相应处理的情形。下列为修改json文件的python脚本供工程后续调用。

# coding=utf-8 //设置文本格式
import os,sys
import json
def get_new_json(filepath,key,value):
        key_ = key.split(".")
        key_length = len(key_)
        with open(filepath, 'rb') as f:
                json_data = json.load(f)
                i = 0
                a = json_data
                while i < key_length :
                        if i+1 == key_length :
                                a[key_[i]] = value
                                i = i + 1
                        else :
                                a = a[key_[i]]
                                i = i + 1
        f.close()
        return json_data
def rewrite_json_file(filepath,json_data):
        with open(filepath, 'w') as f:
                json.dump(json_data,f)
        f.close()
if __name__ == '__main__':
        key = sys.argv[1]
        value = int(sys.argv[2])
        json_path = sys.argv[3]
        m_json_data = get_new_json(json_path,key,value)        
        rewrite_json_file(json_path,m_json_data)
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