手动依赖注入

# DemoNormal\Demo.DI\Demo.DI.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>
  <ItemGroup>
    <ProjectReference Include="..\Demo.Entity\Demo.Entity.csproj" />
    <ProjectReference Include="..\Demo.Service\Demo.Service.csproj" />
  </ItemGroup>
</Project>

DemoNormal\Demo.DI\Program.cs

using Demo.Entity;
using Demo.Service;

//用户信息
var user = new User() { Id = 1, Name = "admin", RoleName = "管理员" };

//新增用户
var userService = new UserService();

userService.AddUser(user);

Console.WriteLine("新增成功！");


//更新用户
userService.UpdateUserRoleName(1, "客服");
Console.WriteLine("更新成功！");

DemoNormal\Demo.Entity\Demo.Entity.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

DemoNormal\Demo.Entity\User.cs

namespace Demo.Entity
{
    /// <summary>
    /// 用户
    /// </summary>
    public class User
    {
        /// <summary>
        /// 用户Id
        /// </summary>
        public long Id { get; set; }

        /// <summary>
        /// 用户名
        /// </summary>
        public string Name { get; set; }

        /// <summary>
        /// 角色名
        /// </summary>
        public string RoleName { get; set; }
    }
}

DemoNormal\Demo.Entity\UserChangeLog.cs

namespace Demo.Entity
{
    /// <summary>
    /// 用户变动日志
    /// </summary>
    public class UserChangeLog
    {
        /// <summary>
        /// Id
        /// </summary>
        public long Id { get; set; }

        /// <summary>
        /// 用户Id
        /// </summary>
        public long UserId { get; set; }

        /// <summary>
        /// 旧角色名称
        /// </summary>
        public string OldRoleName { get; set; }

        /// <summary>
        /// 新角色名称
        /// </summary>
        public string NewRoleName { get; set; }
    }
}

DemoNormal\Demo.Repository\Demo.Repository.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\Demo.Entity\Demo.Entity.csproj" />
  </ItemGroup>

</Project>

DemoNormal\Demo.Repository\UserChangeLogRepository.cs

using Demo.Entity;

namespace Demo.Repository
{
    /// <summary>
    /// 用户变动日志仓储
    /// </summary>
    public class UserChangeLogRepository
    {
        /// <summary>
        /// 构造函数
        /// </summary>
        public UserChangeLogRepository()
        {

        }

        /// <summary>
        /// 新增日志
        /// </summary>
        /// <param name="userChangeLog"></param>
        /// <returns></returns>
        public UserChangeLog AddUserChangeLog(UserChangeLog userChangeLog)
        {
            return userChangeLog;
        }
    }
}

DemoNormal\Demo.Repository\UserRepository.cs

using Demo.Entity;

namespace Demo.Repository
{
    /// <summary>
    /// 用户仓储
    /// </summary>
    public class UserRepository
    {
        /// <summary>
        /// 构造函数
        /// </summary>
        public UserRepository()
        {

        }

        /// <summary>
        /// 添加用户
        /// </summary>
        /// <param name="user"></param>
        /// <returns></returns>
        public User AddUser(User user)
        {
            return user;
        }


        /// <summary>
        /// 获取用户
        /// </summary>
        /// <param name="Id"></param>
        /// <returns></returns>
        public User GetUser(long Id)
        {
            return new User() { Id = 1, Name = "admin", RoleName = "管理员" };
        }

        /// <summary>
        /// 更新用户角色
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="newRoleName"></param>
        public User UpdateUserRoleName(long userId, string newRoleName)
        {
            return new User() { Id = userId, Name = "admin", RoleName = newRoleName };
        }

    }
}

DemoNormal\Demo.Service\Demo.Service.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <ProjectReference Include="..\Demo.Entity\Demo.Entity.csproj" />
    <ProjectReference Include="..\Demo.Repository\Demo.Repository.csproj" />
  </ItemGroup>

</Project>

DemoNormal\Demo.Service\UserChangeLogService.cs

using Demo.Entity;
using Demo.Repository;

namespace Demo.Service
{
    /// <summary>
    /// 用户变动日志
    /// </summary>
    public class UserChangeLogService
    {
        /// <summary>
        /// 用户变动日志仓储
        /// </summary>
        private UserChangeLogRepository _userChangeLogRepository;

        /// <summary>
        /// 用户仓储
        /// </summary>
        private UserRepository _userRepository;

        /// <summary>
        /// 构造函数
        /// </summary>
        public UserChangeLogService()
        {
            _userRepository = new UserRepository();
            _userChangeLogRepository = new UserChangeLogRepository();
        }

        /// <summary>
        /// 新增日志
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="newRoleName"></param>
        /// <returns></returns>
        public UserChangeLog AddUserChangeLog(long userId, string newRoleName)
        {
            //获取用户
            var user = _userRepository.GetUser(userId);

            //变动信息
            var userChangeLog = new UserChangeLog()
            {
                UserId = userId,
                OldRoleName = user.RoleName,
                NewRoleName = newRoleName
            };

            //插入日志
            return _userChangeLogRepository.AddUserChangeLog(userChangeLog);
        }
    }
}

DemoNormal\Demo.Service\UserService.cs

using Demo.Entity;
using Demo.Repository;

namespace Demo.Service
{
    /// <summary>
    /// 用户业务
    /// </summary>
    public class UserService
    {
        /// <summary>
        /// 用户仓储
        /// </summary>
        private UserRepository _userRepository;

        /// <summary>
        /// 用户日志
        /// </summary>
        private UserChangeLogService _userChangeLogService;

        /// <summary>
        /// 构造函数
        /// </summary>
        public UserService()
        {
            _userRepository = new UserRepository();
            _userChangeLogService = new UserChangeLogService();
        }

        /// <summary>
        /// 新增用户
        /// </summary>
        /// <param name="username"></param>
        /// <returns></returns>
        /// <exception cref="ArgumentNullException"></exception>
        public User AddUser(User user)
        {
            //参数校验
            if (user == null)
            {
                throw new ArgumentNullException("用户对象不可为空！");
            }
            if (string.IsNullOrEmpty(user.Name))
            {
                throw new ArgumentNullException("用户名不可为空！");
            }

            //Todo: 业务逻辑

            //保存至数据库,
            return _userRepository.AddUser(user);
        }

        /// <summary>
        /// 更新用户角色
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="newRoleName"></param>
        public void UpdateUserRoleName(long userId, string newRoleName)
        {
            //更新角色
            _userRepository.UpdateUserRoleName(userId, newRoleName);

            //新增日志
            _userChangeLogService.AddUserChangeLog(userId, newRoleName);
        }
    }
}