大家好，在DotNetCore开发中我们会用到DI也就是注入 一般在Program.cs文件中使用IServiceCollection去添加要注入的对象，但在实际开发中我们不可能去频繁的修改Program.cs文件并且把所有业务相关的注入对象都暴露在Program中也是存在开发风险的，因此有必要封装一个自动注入的服务，在Program中仅注册该定制服务就可实现上述需求是最好的方式。本文主要介绍一种符合该定制服务的功能实现。
大概分为以下几部分
1.创建一个自动DI的接口：IModuleInitializer
2.创建实现自动DI接口的实现类：ProjectModuleInitializer
3.给Microsoft.Extensions.DependencyInjection类添加扩展方法(Program中利用IServiceCollection注册相关注入对象用)
4.其他帮助类
整体思路：声明一个接口，在Microsoft.Extensions.DependencyInjection空间下追加扩展类和扩展方法，让该空间下的IServiceCollection能够引入到该扩展方法中，同时该接口在扩展方法中被订阅，这样每个项目中都可以自己写一些实现了该接口的类，在其中注册自己需要的服务，也就是相当于把自动注册这部分封装起来了
下面我们展示代码
1.自动DI注入接口：IModuleInitializer
1 using Microsoft.Extensions.DependencyInjection;
2
3 namespace WebApi.Core.ProjectDependencyInjection
4 {
5 public interface IModuleInitializer
6 {
7 /// <summary>
8 /// 所有项目中的实现了IModuleInitializer接口都会被调用，请在Initialize中编写注册本模块需要的服务。
9 /// 一个项目中可以放多个实现了IModuleInitializer的类。
10 /// 不过为了集中管理，还是建议一个项目中只放一个实现了IModuleInitializer的类
11 /// </summary>
12 public interface IModuleInitializer
13 {
14 public void Initialize(IServiceCollection services);
15 }
16 }
17 }
注意该接口的引用命名空间
using Microsoft.Extensions.DependencyInjection
此处很重要
2.给Microsoft.Extensions.DependencyInjection类添加扩展方法：
创建一个静态类ModuleInitializerExtensions和静态方法RunModuleInitializers
1 using System.Reflection;
2 using static WebApi.Core.ProjectDependencyInjection.IModuleInitializer;
3
4 namespace Microsoft.Extensions.DependencyInjection
5 {
6 public static class ModuleInitializerExtensions
7 {
8 /// <summary>
9 /// 每个项目中都可以自己写一些实现了IModuleInitializer接口的类，在其中注册自己需要的服务，这样避免所有内容到入口项目中注册
10 /// </summary>
11 /// <param name="services">IServiceCollection</param>
12 /// <param name="assemblies">获取工程下所有的项目文件</param>
13 public static IServiceCollection RunModuleInitializers(this IServiceCollection services,
14 IEnumerable<Assembly> assemblies)
15 {
16 //遍历项目文件
17 foreach (var asm in assemblies)
18 {
19 //获取当前文件类型
20 Type[] types = asm.GetTypes();
21 //筛选并获取需要的类型(即:实现了IModuleInitializer接口的类)
22 //筛选条件：非抽象类&&且实现了IModuleInitializer接口
23 var moduleInitializerTypes = types.Where(t => !t.IsAbstract && typeof(IModuleInitializer).IsAssignableFrom(t));
24 foreach (var implType in moduleInitializerTypes)
25 {
26 var initializer = (IModuleInitializer?)Activator.CreateInstance(implType);
27 if (initializer == null)
28 {
29 throw new ApplicationException($"Cannot create ${implType}");
30 }
31 //通过接口实现需要批量注入的指定的业务对象
32 initializer.Initialize(services);
33 }
34 }
35 return services;
36 }
37 }
38 }
注意命名空间和相关引用
3.创建获取解决方案下的所有项目文件获取方法
所需引用：
using System.Diagnostics.CodeAnalysis;
using System.Diagnostics;
using System.Reflection.PortableExecutable;
using System.Reflection;
using System.Reflection.Metadata;
1 public static class ReflectionHelper
2 {
3 /// <summary>
4 /// 据产品名称获取程序集
5 /// </summary>
6 /// <param name="productName"></param>
7 /// <returns></returns>
8 public static IEnumerable<Assembly> GetAssembliesByProductName(string productName)
9 {
10 var asms = AppDomain.CurrentDomain.GetAssemblies();
11 foreach (var asm in asms)
12 {
13 var asmCompanyAttr = asm.GetCustomAttribute<AssemblyProductAttribute>();
14 if (asmCompanyAttr != null && asmCompanyAttr.Product == productName)
15 {
16 yield return asm;
17 }
18 }
19 }
20 //是否是微软等的官方Assembly
21 private static bool IsSystemAssembly(Assembly asm)
22 {
23 var asmCompanyAttr = asm.GetCustomAttribute<AssemblyCompanyAttribute>();
24 if (asmCompanyAttr == null)
25 {
26 return false;
27 }
28 else
29 {
30 string companyName = asmCompanyAttr.Company;
31 return companyName.Contains("Microsoft");
32 }
33 }
34
35 private static bool IsSystemAssembly(string asmPath)
36 {
37 var moduleDef = AsmResolver.DotNet.ModuleDefinition.FromFile(asmPath);
38 var assembly = moduleDef.Assembly;
39 if (assembly == null)
40 {
41 return false;
42 }
43 var asmCompanyAttr = assembly.CustomAttributes.FirstOrDefault(c => c.Constructor?.DeclaringType?.FullName == typeof(AssemblyCompanyAttribute).FullName);
44 if (asmCompanyAttr == null)
45 {
46 return false;
47 }
48 var companyName = ((AsmResolver.Utf8String?)asmCompanyAttr.Signature?.FixedArguments[0]?.Element)?.Value;
49 if (companyName == null)
50 {
51 return false;
52 }
53 return companyName.Contains("Microsoft");
54 }
55
56 /// <summary>
57 /// 判断file这个文件是否是程序集
58 /// </summary>
59 /// <param name="file"></param>
60 /// <returns></returns>
61 private static bool IsManagedAssembly(string file)
62 {
63 using var fs = File.OpenRead(file);
64 using PEReader peReader = new PEReader(fs);
65 return peReader.HasMetadata && peReader.GetMetadataReader().IsAssembly;
66 }
67
68 private static Assembly? TryLoadAssembly(string asmPath)
69 {
70 AssemblyName asmName = AssemblyName.GetAssemblyName(asmPath);
71 Assembly? asm = null;
72 try
73 {
74 asm = Assembly.Load(asmName);
75 }
76 catch (BadImageFormatException ex)
77 {
78 Debug.WriteLine(ex);
79 }
80 catch (FileLoadException ex)
81 {
82 Debug.WriteLine(ex);
83 }
84
85 if (asm == null)
86 {
87 try
88 {
89 asm = Assembly.LoadFile(asmPath);
90 }
91 catch (BadImageFormatException ex)
92 {
93 Debug.WriteLine(ex);
94 }
95 catch (FileLoadException ex)
96 {
97 Debug.WriteLine(ex);
98 }
99 }
100 return asm;
101 }
102
103 /// <summary>
104 /// loop through all assemblies
105 /// </summary>
106 /// <returns></returns>
107 public static IEnumerable<Assembly> GetAllReferencedAssemblies(bool skipSystemAssemblies = true)
108 {
109 Assembly? rootAssembly = Assembly.GetEntryAssembly();
110 if (rootAssembly == null)
111 {
112 rootAssembly = Assembly.GetCallingAssembly();
113 }
114 var returnAssemblies = new HashSet<Assembly>(new AssemblyEquality());
115 var loadedAssemblies = new HashSet<string>();
116 var assembliesToCheck = new Queue<Assembly>();
117 assembliesToCheck.Enqueue(rootAssembly);
118 if (skipSystemAssemblies && IsSystemAssembly(rootAssembly) != false)
119 {
120 if (IsValid(rootAssembly))
121 {
122 returnAssemblies.Add(rootAssembly);
123 }
124 }
125 while (assembliesToCheck.Any())
126 {
127 var assemblyToCheck = assembliesToCheck.Dequeue();
128 foreach (var reference in assemblyToCheck.GetReferencedAssemblies())
129 {
130 if (!loadedAssemblies.Contains(reference.FullName))
131 {
132 var assembly = Assembly.Load(reference);
133 if (skipSystemAssemblies && IsSystemAssembly(assembly))
134 {
135 continue;
136 }
137 assembliesToCheck.Enqueue(assembly);
138 loadedAssemblies.Add(reference.FullName);
139 if (IsValid(assembly))
140 {
141 returnAssemblies.Add(assembly);
142 }
143 }
144 }
145 }
146 var asmsInBaseDir = Directory.EnumerateFiles(AppContext.BaseDirectory,
147 "*.dll", new EnumerationOptions { RecurseSubdirectories = true });
148 foreach (var asmPath in asmsInBaseDir)
149 {
150 if (!IsManagedAssembly(asmPath))
151 {
152 continue;
153 }
154 AssemblyName asmName = AssemblyName.GetAssemblyName(asmPath);
155 //如果程序集已经加载过了就不再加载
156 if (returnAssemblies.Any(x => AssemblyName.ReferenceMatchesDefinition(x.GetName(), asmName)))
157 {
158 continue;
159 }
160 if (skipSystemAssemblies && IsSystemAssembly(asmPath))
161 {
162 continue;
163 }
164 Assembly? asm = TryLoadAssembly(asmPath);
165 if (asm == null)
166 {
167 continue;
168 }
169 //Assembly asm = Assembly.Load(asmName);
170 if (!IsValid(asm))
171 {
172 continue;
173 }
174 if (skipSystemAssemblies && IsSystemAssembly(asm))
175 {
176 continue;
177 }
178 returnAssemblies.Add(asm);
179 }
180 return returnAssemblies.ToArray();
181 }
182
183 private static bool IsValid(Assembly asm)
184 {
185 try
186 {
187 asm.GetTypes();
188 asm.DefinedTypes.ToList();
189 return true;
190 }
191 catch (ReflectionTypeLoadException)
192 {
193 return false;
194 }
195 }
196
197 class AssemblyEquality : EqualityComparer<Assembly>
198 {
199 public override bool Equals(Assembly? x, Assembly? y)
200 {
201 if (x == null && y == null) return true;
202 if (x == null || y == null) return false;
203 return AssemblyName.ReferenceMatchesDefinition(x.GetName(), y.GetName());
204 }
205
206 public override int GetHashCode([DisallowNull] Assembly obj)
207 {
208 return obj.GetName().FullName.GetHashCode();
209 }
210 }
211 }
4.在Progarm.cs中注册封装好的服务
1 public class Program
2 {
3 public static void Main(string[] args)
4 {
5 var builder = WebApplication.CreateBuilder(args);
6
7 //应用各个工程自动DI
8 var asmr = ReflectionHelper.GetAllReferencedAssemblies();
9 builder.Services.RunModuleInitializers(asmr);
10
11 var app = builder.Build();
12 app.UseHttpsRedirection();
13 app.UseAuthentication();
14 app.UseAuthorization();
15 //其他服务注册
16 ...
17 app.MapControllers();
18 app.Run();
19 }
20 }
5.接口实现并进行业务对象注入
注意引用：
using static WebApi.Core.ProjectDependencyInjection.IModuleInitializer;
1 public class ProjectModuleInitializer : IModuleInitializer
2 {
3 public void Initialize(IServiceCollection services)
4 {
5 //DBContext
6 services.AddSingleton(typeof(DBContext<>));
7 //services.AddSingleton(typeof(DBContextFactory<>));
8 //Base
9 services.AddScoped(typeof(IBaseRepository<>), typeof(BaseRepositoryImpl<>));
10 //Book
11 services.AddScoped<IBookRepository, BookRepositoryImpl>();
12 services.AddScoped<IBookService, BookServiceImpl>();
13 //Person
14 services.AddScoped<IPersonRepository, PersonRepositoryImpl>();
15 services.AddScoped<IPersonService, PersonServiceImpl>();
16 //Student
17 services.AddScoped<IStudentRepository, StudentRepositoryImpl>();
18 services.AddScoped<IStudentService, StudentServiceImpl>();
19 //Image
20 services.AddScoped<IImageRepository, ImageRepositoryImpl>();
21 services.AddScoped<IImageService, ImageServiceImpl>();
22 //Product
23 //services.AddScoped<IProductRepository, ProductRepositoryImpl>();
24 services.AddScoped<IProductService, ProductServiceImpl>();
25 }
26 }
项目结构截图：
综上，即可在项目实际开发中进行自动DI注入 不必把所有业务注入对象都在Program.cs中注册
以上 谢谢！
标签：Core,Assembly,DI,services,var,return,Net,public,asm From： https://www.cnblogs.com/bsx133/p/18597830