WEB API 系列（二） Filter的使用以及执行顺序

    public class AuthFilterAttribute : AuthorizationFilterAttribute
    {
        public override void OnAuthorization(HttpActionContext actionContext)
        {
            //如果用户方位的Action带有AllowAnonymousAttribute，则不进行授权验证
            if (actionContext.ActionDescriptor.GetCustomAttributes().Any())
            {
                return;
            }
            var verifyResult = actionContext.Request.Headers.Authorization!=null &&  //要求请求中需要带有Authorization头
                               actionContext.Request.Headers.Authorization.Parameter == "123456"; //并且Authorization参数为123456则验证通过

            if (!verifyResult)
            {
                //如果验证不通过，则返回401错误，并且Body中写入错误原因
                actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.Unauthorized,new HttpError("Token 不正确"));
            }
        }
    }

    public class PersonController : ApiController
    {
        [AuthFilter]
        public CreateResult Post(CreateUser user)
        {
            return new CreateResult() {Id = "123"};
        }
    }

    [AuthFilter]
    public class PersonController : ApiController
    {
        public CreateResult Post(CreateUser user)
        {
            return new CreateResult() {Id = "123"};
        }
    }

public static void Register(HttpConfiguration config)
{
     config.MapHttpAttributeRoutes();
　　  //注册全局Filter
     config.Filters.Add(new AuthFilterAttribute());

     config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );
}

[AllowAnonymous]
public CreateResult PostLogin(LoginEntity entity)
{
      //TODO:添加验证逻辑
      return new CreateResult() {Id = "123456"};
}

 public class CustomActionFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(HttpActionContext actionContext)
    {
        if (!actionContext.ModelState.IsValid)
        {
            actionContext.Response = actionContext.Request.CreateErrorResponse(HttpStatusCode.BadRequest,  actionContext.ModelState);
        }
    }
}

public class LoginEntity
{
    [Required(ErrorMessage = "缺少用户名")]
    public string UserName { get; set; }

    [Required(ErrorMessage = "缺少密码")]
    public string Password { get; set; }
}

[AllowAnonymous]
[CustomActionFilter]
public CreateResult PostLogin(LoginEntity entity)
{
     //TODO:添加验证逻辑
     return new CreateResult() {Id = "123456"};
}

public override async Task OnActionExecutedAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)
{
        var key = 10;

        var responseBody = await actionExecutedContext.Response.Content.ReadAsByteArrayAsync(); //以Byte数组方式读取Content中的数据

        for (int i = 0; i 

public class ExceptionFilter : ExceptionFilterAttribute
{
    public override void OnException(HttpActionExecutedContext actionExecutedContext)
    {
        //如果截获异常为我们自定义，可以处理的异常则通过我们自己的规则处理
        if (actionExecutedContext.Exception is DemoException)
        {
            //TODO:记录日志
            actionExecutedContext.Response = actionExecutedContext.Request.CreateResponse(
                    HttpStatusCode.BadRequest, new {Message = actionExecutedContext.Exception.Message});
        }
        else
        {
            //如果截获异常是我没无法预料的异常，则将通用的返回信息返回给用户，避免泄露过多信息，也便于用户处理

            //TODO:记录日志
            actionExecutedContext.Response =
                    actionExecutedContext.Request.CreateResponse(HttpStatusCode.InternalServerError,
                        new {Message = "服务器被外星人拐跑了！"});
        }
    }
}

 [CustomerExceptionFilter]
public class TestController : ApiController
{
    public int Get(int a, int b)
    {
        if (a