使用单一职责原理重新分解程序-SOLID- SRP

Question

我正在学习SOLID，并且试图理解单一责任原则。

WalkingData类存储“日期”和“步行距离”。该类还读取存储的数据。

 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之后，我想确认是否以合理的方式应用了该原则的新代码：

//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（WalkingDataRepository）的责任，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不仅涉及分解功能，还涉及封装它们！我也wrote an article。

[困扰我的是anemic WalkingData模型。这是一种反模式。您应该让WalkingData处理维护自己的数据的责任，而不是创建另一个类WalkingDataManager来完成这项工作。