使用单一职责原则重构程序 - SOLID-SRP

Question

我正在学习 SOLID，我正在尝试理解单一职责原则。

classWalkingData存储了一个"date"和一个"walked distance"。 class也读取存储的数据。

 public class WalkingData
    {
        public DateTime Date { get; set; }
        public int WalkedDistance { get; set; }
        private string _filePath = @"c:\Data\Json.txt";

        //Read Data from Json File
        public List<WalkingData> GetAll()
        {
            //If file does not exist returns an empty list
            if (!File.Exists(_filePath)) return new List<WalkingData>();

            string jsonData;

            //Read the existing Json file
            using (StreamReader readtext = new StreamReader(_filePath))
            {
                jsonData = readtext.ReadToEnd();
            }

            //Deserialize the Json and returs a list of WalkingData
            return JsonConvert.DeserializeObject<List<WalkingData>>(jsonData);            
        }

        //save an instance of  WalkingData in Json file
        public void Save()
        {
            List<WalkingData> lstExistingWalkingData = new List<WalkingData>();

            //if existing data, load it into lstExistingWalkingData
            if (File.Exists(_filePath))
                lstExistingWalkingData = GetAll();

            //Add the current instace into lstExistingWalkingData
            lstExistingWalkingData.Add(this);

            //Serialize lstExistingWalkingData
            string output = JsonConvert.SerializeObject(lstExistingWalkingData);

            //Save the Json file
            using (StreamWriter w = new StreamWriter(_filePath))
            {
                w.WriteLine(output);
            }
        }      
    }

在我应用单一责任原则后，我有了新代码，我想确认我是否以合理的方式应用了该原则：

//This class is located on a library called BOL and has a reference to DAL library
    public class WalkingData
    {
        public DateTime Date { get; set; }
        public int WalkedDistance { get; set; }
    }

    //This class is located on a library called BOL and has a reference to DAL library
    public class WalkingDataManager
    {        
        WalkingDataRepository walkingDataRepository = new WalkingDataRepository();

        public List<WalkingData> GetAll()
        {
            return walkingDataRepository.GetAll();
        }

        public void Save(WalkingData walkingData)
        {
            walkingDataRepository.Save(walkingData);
        }
    }

    //this class is located in library Called DAL
    internal class WalkingDataRepository
    {
        private string _filePath = @"c:\Data\Json.txt";

        //Read Data from Json File
        internal List<WalkingData> GetAll()
        {
            //If file does not exist returns an empty list
            if (!File.Exists(_filePath)) return new List<WalkingData>();

            string jsonData;

            //Read the existing Json file
            using (StreamReader readtext = new StreamReader(_filePath))
            {
                jsonData = readtext.ReadToEnd();
            }

            //Deserialize the Json and returs a list of WalkingData
            return JsonConvert.DeserializeObject<List<WalkingData>>(jsonData);
        }

        //save an instance of  WalkingData in Json file
        internal void Save(WalkingData walkingData)
        {
            List<WalkingData> lstExistingWalkingData = new List<WalkingData>();

            //if existing data, load it into lstExistingWalkingData
            if (File.Exists(_filePath))
                lstExistingWalkingData = GetAll();

            //Add the current instace into lstExistingWalkingData
            lstExistingWalkingData.Add(walkingData);

            //Serialize lstExistingWalkingData
            string output = JsonConvert.SerializeObject(lstExistingWalkingData);

            //Save the Json file
            using (StreamWriter w = new StreamWriter(_filePath))
            {
                w.WriteLine(output);
            }
        }
    }

Answer 1

您分离了保存数据的职责(WalkingDataRepository)，并将其封装在WalkingDataManager中。重构工作完全符合 SRP 所说的。简而言之，SRP 不仅要分解功能，还要封装它们！我也wrote an article了。

困扰我的是 anemic WalkingData 模型。这是一个反模式。您应该让 WalkingData 负责维护自己的数据，而不是创建另一个 class WalkingDataManager 来完成这项工作。

使用单一职责原则重构程序 - SOLID-SRP

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