前言

本文开始前先简单介绍一下DDD分层的概念
表现层（Presentation Layer）：图中的用户界面层包括用户接口层，用户输入和数据展示。
应用层（Application Layer）：应用层定义系统的业务功能，并指挥领域层中的领域对象实现这些功能。
领域层（Domain Layer）：核心层，实现所有业务逻辑。
基础设施层（Infrastructure Layer）：提供整个业务系统的基础服务。
接下来将手动创建各层
领域层已经在上一章创建完成 xxx.xxx.Domain

一、完善框架

1.领域层-仓储

在xxx.xxx.Domain项目中新建接口 IBasicDictionaryRepository

/// <summary>
    /// 基本字典仓储接口
    /// </summary>
    public interface IBasicDictionaryRepository
    {
        /// <summary>
        /// 创建基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        BasicDictionary Post(BasicDictionary basicDictionary);

        /// <summary>
        /// 修改基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        int Put(Guid id, BasicDictionary basicDictionary);

        /// <summary>
        /// 删除基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        int Delete(Guid basicDictionary);

        /// <summary>
        /// 查询基础字典
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        IList<BasicDictionary> Get(BasicDictionaryType type);
    }

在xxx.xxx.EntityFrameworkCore中添加接口 IBasicDictionaryRepository的实现 BasicDictionaryRepository

/// <summary>
    /// 基本字典仓储实现
    /// </summary>
    public class BasicDictionaryRepository : IBasicDictionaryRepository
    {
        private PSIDbContext _context;

        public BasicDictionaryRepository()
        {
            var configurationBuilder = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json");
            var config = configurationBuilder.Build();
            string connection = config["connectionStrings:default"];
            DbContextOptions<PSIDbContext> dbContextOption = new DbContextOptions<PSIDbContext>();
            DbContextOptionsBuilder<PSIDbContext> dbContextOptionBuilder = new DbContextOptionsBuilder<PSIDbContext>(dbContextOption);
            _context = new PSIDbContext(dbContextOptionBuilder.UseSqlServer(connection).Options);
        }

        /// <summary>
        /// 创建基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        public BasicDictionary Post(BasicDictionary basicDictionary)
        {
            using (_context)
            {
                _context.Add(basicDictionary);
                _context.SaveChanges();

                return basicDictionary;
            }
        }

        /// <summary>
        /// 修改基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        public int Put(Guid id, BasicDictionary basicDictionary)
        {
            using (_context)
            {
                var item = _context.BasicDictionaries.Where(b => b.ID == id).FirstOrDefault();

                if (item != null)
                {
                    item.Sort = basicDictionary.Sort;
                    item.Name = basicDictionary.Name;
                    item.PinYinCode = basicDictionary.PinYinCode;
                }

                return _context.SaveChanges();
            }
        }

        /// <summary>
        /// 删除基础字典
        /// </summary>
        /// <param name="basicDictionary"></param>
        /// <returns></returns>
        public int Delete(Guid id)
        {
            using (_context)
            {
                var item = _context.BasicDictionaries.Where(b => b.ID == id).FirstOrDefault();

                if (item != null)
                {
                    _context.Remove(item);
                }

                return _context.SaveChanges();
            }
        }

        /// <summary>
        /// 查询基础字典
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public IList<BasicDictionary> Get(BasicDictionaryType type)
        {
            using (_context)
            {
                var item = _context.BasicDictionaries.Where(b => b.Type == type).OrderBy(o => o.Sort).ToList();

                return item;
            }
        }
    }

2.应用层

新建类库-应用层，名称可自定义如xxx.xxx.Application
新建类库-应用层契约，名称可自定义如xxx.xxx.Application.Contracts
在应用层中添加类BasicDictionaryService

/// <summary>
    /// 基础字典服务
    /// </summary>
    public class BasicDictionaryService : IBasicDictionaryService
    {
        private IBasicDictionaryRepository _basicDictionaryRepository;

        public BasicDictionaryService()
        {
            _basicDictionaryRepository = new BasicDictionaryRepository();
        }

        /// <summary>
        /// 查询基础字典
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        public IList<BasicDictionary> Get(BasicDictionaryType type)
        {
            return _basicDictionaryRepository.Get(type);
        }
    }

在应用契约层添加BasicDictionaryDto

public class BasicDictionaryDto
    {
        [Key]
        public Guid ID { get; set; }

        /// <summary>
        /// 字典代码
        /// </summary>
        [MaxLength(40), Required]
        public string Code { get; set; }

        /// <summary>
        /// 字典名称
        /// </summary>
        [MaxLength(80), Required]
        public string Name { get; set; }

        /// <summary>
        /// 拼音码
        /// </summary>
        [MaxLength(40), Required]
        public string PinYinCode { get; set; }

        /// <summary>
        /// 字典类型
        /// </summary>
        [Required]
        public BasicDictionaryType Type { get; set; }

        /// <summary>
        /// 字典状态
        /// </summary>
        [Required]
        public BasicDictionaryStatus Status { get; set; }

        /// <summary>
        /// 排序
        /// </summary>
        [Required]
        public int Sort { get; set; }
    }

3.展现层

新建Asp.Net core Web API，名称可自定义如 xxx.xxx.HttpApi.Host
在Program.cs中添加依赖注入 IBasicDictionaryService

using Yudian.PSI.Application;
using Yudian.PSI.Application.Contracts;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

#region Services

builder.Services.AddTransient<IBasicDictionaryService, BasicDictionaryService>();

#endregion

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseAuthorization();

app.MapControllers();

app.Run();

添加controller

/// <summary>
    /// 基础字典服务
    /// </summary>
    [Route("psi/[controller]/v1")]
    [ApiController]
    public class BasicDictionaryController : ControllerBase
    {
        private IBasicDictionaryService _basicDictionaryService;

        public BasicDictionaryController(IBasicDictionaryService basicDictionaryService)
        {
            _basicDictionaryService = basicDictionaryService;
        }

        /// <summary>
        /// 根据类别获取基础字典列表
        /// </summary>
        /// <param name="type"></param>
        /// <returns></returns>
        [HttpGet]
        [Route("{type}")]
        public async Task<IActionResult> Get(BasicDictionaryType type)
        {
            var items = await Task.Factory.StartNew(() =>
            {
                return _basicDictionaryService.Get(type);
            });

            return Ok(items);
        }
    }

总结

最终项目目录结构如下

以上就是今天要讲的内容，下一章节将介绍依赖注入部分。