(更新时间)2021年5月31日 商城高并发秒杀系统(.NET Core版) 15-通用用户模型绑定的封装

一：通用用户模型绑定的封装

/// <summary>
/// 系统用户(用于存储用户状态相关信息)
/// </summary>
public class SysUser
{
    public int UserId { set; get; } // 用户Id
    public string UserName { set; get; } // 用户名称
}

/// <summary>
/// 系统用户模型绑定(从头部信息获取用户信息，UserId和UserName)
/// 1、将HttpContext用户信息转换成为Sysuser
/// 2、将Sysuser绑定到action方法参数
/// </summary>
public class SysUserCookieModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException(nameof(bindingContext));
        }
        if (bindingContext.ModelType == typeof(SysUser))
        {
            // 1、创建用户对象
            SysUser sysUser = new SysUser();

            // 2、设置模型值(cookie，header)
            HttpContext httpContext = bindingContext.HttpContext;
            IRequestCookieCollection cookies = httpContext.Request.Cookies;
            string UserId = cookies["UserId"];
            string UserName = cookies["UserName"];
            // 1、判断UserId是否为空
            if (string.IsNullOrEmpty(UserId))
            {
                throw new BizException("授权失败，没有登录");
            }
            sysUser.UserId = Convert.ToInt32(UserId);
            sysUser.UserName = UserName;

            // 3、返回结果
            bindingContext.Result = ModelBindingResult.Success(sysUser);

        }

        return Task.CompletedTask;
    }
}

/// <summary>
/// 系统用户模型绑定(从头部信息获取用户信息，UserId和UserName)
/// 1、将HttpContext用户信息转换成为Sysuser
/// 2、将Sysuser绑定到action方法参数
/// </summary>
public class SysUserHeaderModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException(nameof(bindingContext));
        }
        if (bindingContext.ModelType == typeof(SysUser))
        {
            // 1、创建用户对象
            SysUser sysUser = new SysUser();

            // 2、设置模型值(cookie，header)
            HttpContext httpContext = bindingContext.HttpContext;
            IHeaderDictionary headers = httpContext.Request.Headers;
            string UserId = headers["UserId"];
            string UserName = headers["UserName"];
            // 1、判断UserId是否为空
            if (string.IsNullOrEmpty(UserId))
            {
                throw new BizException("授权失败，没有登录");
            }
            sysUser.UserId = Convert.ToInt32(UserId);
            sysUser.UserName = UserName;

            // 3、返回结果
            bindingContext.Result = ModelBindingResult.Success(sysUser);

        }

        return Task.CompletedTask;
    }
}

/// <summary>
/// 系统用户模型绑定
/// 1、将HttpContext用户信息转换成为Sysuser
/// 2、将Sysuser绑定到action方法参数
/// </summary>
public class SysUserModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException(nameof(bindingContext));
        }
        if (bindingContext.ModelType == typeof(SysUser))
        {
            // 1、转换到指定模型
            //  SysUser sysUser = (SysUser)bindingContext.Model;
            SysUser sysUser = new SysUser();

            // 2、设置模型值(cookie，header)
            HttpContext httpContext = bindingContext.HttpContext;
            ClaimsPrincipal claimsPrincipal = httpContext.User;
            IEnumerable<Claim> claims = claimsPrincipal.Claims;
            // 1、判断申明是否为空，如果为空，没有登录，抛出异常
            if (claims.ToList().Count == 0)
            {
                throw new BizException("授权失败，没有登录");
            }
            foreach (var claim in claims)
            {
                // 1、获取用户Id
                if (claim.Type.Equals("sub"))
                {
                    sysUser.UserId = Convert.ToInt32(claim.Value);
                }

                // 2、获取用户名
                if (claim.Type.Equals("amr"))
                {
                    sysUser.UserName = claim.Value;
                }
            }

            // 3、返回结果
            bindingContext.Result = ModelBindingResult.Success(sysUser);

        }

        return Task.CompletedTask;
    }
}

/// <summary>
/// 自定义模型绑定提供者(提供SysUserModelBinder)
/// </summary>
public class SysUserModelBinderProvider : IModelBinderProvider
{
    public IModelBinder GetBinder(ModelBinderProviderContext context)
    {
        if (context == null)
        {
            throw new ArgumentNullException(nameof(context));
        }

        if (context.Metadata.ModelType == typeof(SysUser))
        {
            return new BinderTypeModelBinder(typeof(SysUserHeaderModelBinder));
        }

        return null;
    }
}