自定义IOC

为什么不直接用Core自带的IOC?
1. 能够理解本质
2. 扩展性更强

接上一章扩展 ： 《.Net Core 3.x MVC DIP与Factory》

这章完成目标：
1.多参数
2.多构造函数（参数数量/特性标识）

开始撸码

在 AspNetCore.IOCDI.Framework 添加 容器接口 和 容器实现类

容器实现 ，这里容器实现了无限级递归，和 特性标记

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace AspNetCore.IOCDI.Framework.CustomContainer
{
    /// <summary>
    /// 用来生产对象
    /// 第三方   业务无关性
    /// </summary>
    public class CoreContainer: ICoreContainer
    {
        private Dictionary<string, Type> CoreContainerDictionary = new Dictionary<string, Type>();

        /// <summary>
        /// where TTo 必须是 TFrom 类型的约束
        /// </summary>
        public void Register<TFrom, TTo>() where TTo: TFrom
        {
            //用TFrom的名称作为Key ,用 TTo 这个类型作为Value
            this.CoreContainerDictionary.Add(typeof(TFrom).FullName,typeof(TTo));
        }

        /// <summary>
        /// 用类型名称找出类型，返回 创建好的对象
        /// </summary>
        /// <typeparam name="TFrom"></typeparam>
        /// <returns></returns>
        public TFrom Resolve<TFrom>() {
            return (TFrom)this.ResolveObject(typeof(TFrom));
        }

        /// <summary>
        /// 递归--可以完成不限层级的东西
        /// </summary>
        private object ResolveObject(Type abstracttype)
        {
            string key = abstracttype.FullName;

            Type type = this.CoreContainerDictionary[key];

            #region 选择适合的构造函数

            ConstructorInfo ctor = null;
            
            //是否有标记，有特性标记用特性标记，没有就用参数最多的
            ctor = type.GetConstructors().FirstOrDefault(c => c.IsDefined(typeof(CoreConstructorAttribute), true));
            if (ctor == null)
            {
                //找参数最多的
                ctor = type.GetConstructors().OrderByDescending(c => c.GetParameters().Length).First();
            }
            
            #endregion


            #region 准备构造函数的参数

            List<object> paraList = new List<object>();

            foreach (var para in ctor.GetParameters())
            {
                Type paraType = para.ParameterType;//获取参数的类型 IUserDAL
                
                object paraInstance = this.ResolveObject(paraType);
                
                paraList.Add(paraInstance);
            }

            #endregion

            object oInstance = Activator.CreateInstance(type, paraList.ToArray());

            return oInstance;
        }
    }
}

TestServiceA 实现

using AspNetCore.IOCDI.Interface;
using System;

namespace AspNetCore.IOCDI.Service
{
    public class TestServiceA : ITestServiceA
    {
        public TestServiceA() {
            Console.WriteLine($"{ this.GetType().Name }被构造。。。");
        }

        public void Show()
        {
            Console.WriteLine("这里是 TestServiceA Show.");
        }
    }
}

TestServiceB 实现

using AspNetCore.IOCDI.Interface;
using System;

namespace AspNetCore.IOCDI.Service
{
    public class TestServiceB : ITestServiceB
    {
        
        public TestServiceB(ITestServiceA iTestServiceA) {
            Console.WriteLine($"{ this.GetType().Name }被构造。。。");
        }

        private ITestServiceA _iTestServiceA = null;

        public void Init(ITestServiceA testServiceA) {
            this._iTestServiceA = testServiceA;
        }

        public void Show()
        {
            Console.WriteLine("这里是 TestServiceB Show.");
        }
    }
}