python基础：数据持久化工具类pickle,shelve

梦里梦外; 2022-03-21 18:44 224阅读 0赞

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# 1, 使用pickle：数据读写 #

pickleTest.py

#使用： python模块的工具类， 数据持久化
    import pickle
    from chapter1.res.list_map import db
    
    #保存数据 ,到文件流
    pickstream=open("data/pickle-data.txt","wb")
    pickle.dump(db, pickstream)
    
    #读取已保存的数据
    # pickstream=open("data/pickle-data.txt","rb")
    # db_data=pickle.load(pickstream)
    # for key in db_data:
    #     print(key, ",",  db_data[key])
    
    #关闭流
    pickstream.close()

pickleTest2.py

#每条数据，保存在各自的文件中
    import pickle,glob
    from chapter1.res.list_map import bob,sue
    
    def save_data_each_file(): #将字典dict存入到文件中
        for (key ,val) in  [("bob",bob), ("sue",sue)]:
            print(key, val)
            #保存数据
            filename="data/"+key+"-data.txt"
            output=open(filename,"wb")
            pickle.dump(val,output)
            #关闭文件流
            output.close()
    
    def load_data_from_file():
        for file in glob.glob("data/*-data.txt"):
            if file.__contains__("pickle"):
               pass #不处理其他文件
            else:
                print(file,"======")
                #加载数据
                input=open(file,"rb")
                data=pickle.load(input)
                for key in data:
                    print(key, ",", data[key])
    
    if __name__=="__main__":
    	save_data_each_file()
        load_data_from_file()
    
    #data\bob-data.txt ======
    #name , bob jones
    #age , 32
    #pay , 30000
    #job , dev
    #data\sue-data.txt ======
    #name , sue smith
    #age , 42
    #pay , 40000
    #job , dev

# 2, 使用shelve：读写文件 #

shelveTest.py

#使用shelve工具类， 持久化数据
    import  shelve
    file_name ="data/shelve-data"
    
    #创建字典，写入数据
    def save_data():
        # Open a persistent dictionary for reading and writing.
        shelve_dict=shelve.open(file_name)
        shelve_dict["tom"]={"name":"tom","pay":230000,"job":"dev"}
        shelve_dict["sue"]={"name":"sue", "pay":300000, "job":"java-enginer"}
        shelve_dict.close()
    
    def read_data():
        shelve_dict=shelve.open(file_name)
        tom_dict=shelve_dict["tom"]
        print(tom_dict) #{'name': 'tom', 'pay': 230000, 'job': 'dev'}
        shelve_dict.close()
    
    def update_data():
        shelve_dict=shelve.open(file_name)
        tom_dict=shelve_dict["tom"]
        tom_dict["name"]="tom2 tom2"
        tom_dict["pay"]=500000
    
        shelve_dict["tom"]=tom_dict#替换原数据
        shelve_dict.close()
    
    if __name__ == "__main__":
        save_data()
        read_data()
        update_data()
        print("change-----------")
        read_data()
        
    #{'name': 'tom', 'pay': 230000, 'job': 'dev'}
    #change-----------
    #{'name': 'tom2 tom2', 'pay': 500000, 'job': 'dev'}

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