ASP.NET Core Web API依赖注入报错：无法构造邮件服务类

问题原因 #

1. 未注册EmailConfigurations服务：MailService和EmailSender的构造函数都依赖EmailConfigurations，但你仅在DI容器中注册了服务接口与实现类，未将EmailConfigurations本身注册进去，导致容器无法解析该类型的依赖。
2. ILogger注入不规范：使用非泛型ILogger会导致DI容器无法正确识别日志类别，应使用泛型版本ILogger<T>。

解决步骤 #

1. 配置文件添加邮件参数 #

在appsettings.json中新增邮件配置节点：

"EmailConfigurations": {
  "SmtpHost": "smtp.example.com",
  "SenderName": "发件人名称",
  "SenderEmail": "your-email@example.com",
  "SmtpPort": 587,
  "Username": "your-email@example.com",
  "Password": "邮箱密码或授权码"
}

2. 修改DI扩展方法，注册配置类 #

更新DIServiceExtension类，添加配置绑定与注册逻辑：

public static class DIServiceExtension
{
    public static void AddDependencyInjection(this IServiceCollection services, IConfiguration configuration)
    {
        // 从配置文件读取并注册EmailConfigurations为单例
        var emailConfig = configuration.GetSection("EmailConfigurations").Get<EmailConfigurations>();
        services.AddSingleton(emailConfig);

        services.AddScoped<IAuthService, AuthService>();
        services.AddScoped<ITokenGeneratorService, TokenGeneratorService>();
        services.AddScoped<ITokenRepository, TokenRepository>();
        services.AddTransient<IMailService, MailService>();
        services.AddScoped<IEmailSender, EmailSender>();
    }
}

3. 修正ILogger注入为泛型版本 #

修改MailService构造函数：

public class MailService : IMailService
{
    private readonly ILogger<MailService> _logger;
    private readonly EmailConfigurations _emailConfig;

    public MailService(ILogger<MailService> logger, EmailConfigurations emailConfig)
    {
        _logger = logger;
        _emailConfig = emailConfig;
    }
    // SendEmailAsync方法实现...
}

修改EmailSender构造函数：

public class EmailSender : IEmailSender
{
    private readonly EmailConfigurations _emailConfig;
    private readonly ILogger<EmailSender> _logger;

    public EmailSender(EmailConfigurations emailConfig, ILogger<EmailSender> logger)
    {
        _emailConfig = emailConfig;
        _logger = logger;
    }
    // 邮件发送方法实现...
}

4. 更新Program.cs的扩展方法调用 #

将配置对象传入扩展方法：

builder.Services.AddDependencyInjection(builder.Configuration);
var app = builder.Build();

内容的提问来源于stack exchange，提问作者Ayobamilaye