如何在Autofac的RegisterAssemblyTypes中按类名长度排序解决注入错误

问题背景 #

有两个以Service结尾的服务类：TurnoverGroupWebService和CashregisterTurnoverGroupWebService，本该分别注册到IReadTurnoverGroupWebService和IReadCashregisterTurnoverGroupWebService接口，但因为两者都以TurnoverGroupWebService结尾，导致CashregisterTurnoverGroupWebService被错误注入接口。当前注册代码如下：

public class AutofacHelper
{
    public static void ScanAssembly(Assembly thisAssembly, ContainerBuilder builder)
    {
        var registerTypeStrings = GetRegisterTypeStrings();
        foreach (var item in registerTypeStrings)
        {
            builder.RegisterAssemblyTypes(thisAssembly)
                .Where(t => t.Name.EndsWith(item))
                .AsImplementedInterfaces()
                .SingleInstance();
        }
    }
}

你尝试通过OrderByDescending按类型名称长度排序来解决问题，但因RegisterAssemblyTypes返回的不是可枚举集合，导致编译报错：

builder.RegisterAssemblyTypes(thisAssembly)
                .OrderByDescending(t => t.Name.Length)
                .Where(t => t.Name.EndsWith(item))
                .AsImplementedInterfaces()
                .SingleInstance();

解决方案 #

Autofac的RegisterAssemblyTypes返回的是IRegistrationBuilder而非可枚举集合，无法直接使用OrderByDescending。可以通过以下两种方式实现精准匹配：

方式一：先排序类型再逐个注册 #

先筛选出所有符合后缀条件的类型，按名称长度倒序排序后逐个注册，确保更长的类名优先匹配对应接口：

public class AutofacHelper
{
    public static void ScanAssembly(Assembly thisAssembly, ContainerBuilder builder)
    {
        var registerTypeStrings = GetRegisterTypeStrings();
        // 筛选所有符合后缀的类型并按名称长度倒序
        var targetTypes = thisAssembly.GetTypes()
                                      .Where(t => registerTypeStrings.Any(s => t.Name.EndsWith(s)))
                                      .OrderByDescending(t => t.Name.Length)
                                      .ToList();

        foreach (var type in targetTypes)
        {
            // 找到当前类型匹配的最长后缀，避免短后缀误匹配
            var matchedSuffix = registerTypeStrings.OrderByDescending(s => s.Length)
                                                   .First(s => type.Name.EndsWith(s));
            builder.RegisterType(type)
                   .AsImplementedInterfaces()
                   .SingleInstance();
        }
    }
}

方式二：先排序后缀列表再过滤注册 #

对registerTypeStrings按长度倒序排列，优先处理更长的后缀，同时过滤已匹配过长后缀的类型，避免重复注册：

public class AutofacHelper
{
    public static void ScanAssembly(Assembly thisAssembly, ContainerBuilder builder)
    {
        var registerTypeStrings = GetRegisterTypeStrings()
                                 .OrderByDescending(s => s.Length)
                                 .ToList();
        foreach (var item in registerTypeStrings)
        {
            builder.RegisterAssemblyTypes(thisAssembly)
                .Where(t => t.Name.EndsWith(item) 
                          // 排除已匹配更长后缀的类型
                          && !registerTypeStrings.Any(s => s.Length > item.Length && t.Name.EndsWith(s)))
                .AsImplementedInterfaces()
                .SingleInstance();
        }
    }
}

原理说明 #

两种方式核心逻辑一致：优先匹配更长的后缀或类名，确保CashregisterTurnoverGroupWebService不会被TurnoverGroupWebService的短后缀规则误匹配，从而正确关联到IReadCashregisterTurnoverGroupWebService接口。

内容的提问来源于stack exchange，提问作者J. Rahmati