WebApi中过滤器的AOP实现方式

Posted 2020-07-01

     说到AOP编程，可能大部分人是即熟悉又显得陌生。

    AOP的作用就是横切关注点，然后将分离后的关注点以面的形式来呈现，这是概念性的说法，举个列子来说明吧。

     比如说有个API接口处理场景是提交订单，在我们提交订单的时候，首先客户端要对用户提交的数据进行合法性验证，验证通过后，数据发送到服务端，因客户端一切操作都是不可信的，必然服务端在录入订单信息之前也需要对数据合法性进行验证。

    针对上述问题我们可以这样子来编码

    首先定义订单表单参数实体对象：

 

 1 /// <summary>
 2     /// Post表单参数
 3     /// </summary>
 4     public class FromOrderInfo
 5     {
 6         /// <summary>
 7         /// 商品名称
 8         /// </summary>
 9         public string ShopName { get; set; }
10         /// <summary>
11         /// 手机号
12         /// </summary>
13         [ValidateMobile(ErrorMessage = "请输入正确格式的手机号")]//自定义验证规则
14         public string Mobile { get; set; }
15         /// <summary>
16         /// Address
17         /// </summary>
18         [ValidateMaxLength(20,ErrorMessage = "Address字符超过指定长度")]
19         public string Address { get; set; }
20     } 
 

 

自定义验证如下：

 1 /// <summary>
 2     /// 验证字符长度是否超过指定长度
 3     /// </summary>
 4     public class ValidateMaxLengthAttribute : ValidationAttribute
 5     {
 6         private readonly int MaxLength;
 7 
 8         public ValidateMaxLengthAttribute(int maxLength)
 9             : base("{0}的字符太多了!")
10         {
11             MaxLength = maxLength;
12         }
13 
14         protected override ValidationResult IsValid(object value, ValidationContext validationContext)
15         {
16             if (value != null)
17             {
18                 string content = value.ToString();
19                 int leng = StringTool.GetStringLength(content);
20                 if (leng > MaxLength)
21                 {
22                     string errorMessage = FormatErrorMessage(validationContext.DisplayName);
23                     return new ValidationResult(errorMessage);
24                 }
25             }
26             return ValidationResult.Success;
27         }       
28     }
29 
30 /// <summary>
31    /// 验证手机号
32    /// </summary>
33    public class ValidateMobileAttribute : ValidationAttribute
34     {
35        public ValidateMobileAttribute()
36             : base("{0}应输入11位手机号!")
37         {
38         }
39        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
40        {
41            if (value != null)
42            {
43                string content = value.ToString();
44                if (!RegexTool.IsMobile(content))
45                {
46                    string errorMessage = FormatErrorMessage(validationContext.DisplayName);
47                    return new ValidationResult(errorMessage);
48                }
49            }
50            return ValidationResult.Success;
51        }
52     }

View Code

订单API接口：

 1  [CHKFormInput(typeof(FromOrderInfo))]
 2         public HttpResponseMessage TestOrder([FromBody] FromInfo info)
 3         {
 4             var challengeMessage = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.OK);
 5 
 6             challengeMessage = new ResponseMessage<string>("json").Response("下单成功");
 7             return challengeMessage;
 8 
 9         }
10 
11 /// <summary>
12     /// Post表单参数
13     /// </summary>
14     public class FromInfo
15     {
16         /// <summary>
17         /// Json数据对象
18         /// </summary>
19         public string JsonFormat { get; set; }
20     }

View Code

 

 

定义过滤器：

 1 /// <summary>
 2     /// 验证表单参数
 3     /// </summary>
 4 public class CHKFormInput : ActionFilterAttribute
 5     {
 6         private Type _type;
 7         /// <summary>
 8         /// 构造函数
 9         /// </summary>
10         /// <param name="type">表单参数验证对象</param>
11         public CHKFormInput(Type type = null)
12         {
13             if (type != null)
14             {
15                 this._type = type;
16             }
17         }
18         public override void OnActionExecuting(HttpActionContext actionContext)//执行action动作所需执行的操作
19         {
20             #region 检查表单参数是否合法
21             var challengeMessage = new System.Net.Http.HttpResponseMessage(System.Net.HttpStatusCode.OK);
22             ErrorResponse errorMsgConvertjson = new ErrorResponse();//返回错误信息string errorMsg = string.Empty;
23             try
24             {
25                 if (actionContext == null)
26                 {
27                     throw new System.Web.Http.HttpResponseException(challengeMessage);
28                 }
29                 if (ProjectRequest.IsPost())//验证是否POST请求
30                 {
31                     var task = actionContext.Request.Content.ReadAsStreamAsync();
32                     var content = string.Empty;
33                     using (System.IO.Stream sm = task.Result)
34                     {
35                         if (sm != null)
36                         {
37                             sm.Seek(0, SeekOrigin.Begin);
38                             int len = (int)sm.Length;
39                             byte[] inputByts = new byte[len];
40                             sm.Read(inputByts, 0, len);
41                             sm.Close();
42                             content = Encoding.UTF8.GetString(inputByts);
43                         }
44                     }
45                     var m = JsonTool.JsonToEntity<FromInfo>(content);
46                     var Json = Serializer.Deserialize(m.JsonFormat, _type);
47                     new TryValidateModelTool().TryValidateModel(Json, ref errorMsg);
48                     if(!string.IsNullOrEmpty(errorMsg))
49                     {
50                         errorMsgConvertjson.Message = errorMsg;
51                         errorMsgConvertjson.State = CallBackServer.InputError;
52                         challengeMessage = new ResponseMessage<ErrorResponse>("json").Response(errorMsgConvertjson);
53                         actionContext.Response = challengeMessage;
54                     }
55                     
56                 }
57                 
58             }
59             catch (Exception ex)
60             {
61             }
62             finally
63             {
64             }
65             base.OnActionExecuting(actionContext);
66             #endregion
67         }
68     }

View Code

 

 

实体对像属性验证类：

 1 /// <summary>
 2     /// 利用特性验证实体对象参数合法性
 3     /// </summary>
 4     public class TryValidateModelTool : ApiController
 5     {
 6         /// <summary>
 7         /// 利用特性验证实体对象参数合法性
 8         /// </summary>
 9         /// <param name="model">对象</param>
10         /// <param name="errorMsg">错误信息</param>
11         /// <returns></returns>
12         public bool TryValidateModel(object model, ref string errorMsg)
13         {
14             return TryValidateModel(model, null /* prefix */, ref errorMsg);
15         }
16 
17         
18 
19 
20         /// <summary>
21         /// 利用特性验证实体对象参数合法性
22         /// </summary>
23         /// <param name="model">对象</param>
24         /// <param name="errorMsg">错误信息</param>
25         /// <returns></returns>
26         public bool TryValidateModel(object model, string prefix, ref string errorMsg)
27         {
28             if (model == null)
29             {
30                 throw new ArgumentNullException("model");
31             }
32 
33             ModelMetadata metadata = ModelMetadataProviders.Current.GetMetadataForType(() => model, model.GetType());
34             var t = new ModelBindingExecutionContext(new HttpContextWrapper(HttpContext.Current), new System.Web.ModelBinding.ModelStateDictionary());
35             List<string> errorMsgList = new List<string>();
36             foreach (ModelValidationResult validationResult in ModelValidator.GetModelValidator(metadata, t).Validate(null))
37             {
38                 ModelState.AddModelError(validationResult.MemberName, validationResult.Message);
39                 errorMsgList.Add(validationResult.Message);
40             }                       
41             errorMsg = string.Join(",", errorMsgList);
42             return ModelState.IsValid;
43         }
44     }

View Code

 

 

至此整个AOP过滤器编码全部完成，在用户提交表单之前，API接口会首先进入CHKFormInput 过滤器验证参数合法性，如验证失败，将不进入提交订单的API接口

感谢您的阅读！