[AttributeUsage(AttributeTargets.Property)]public class StringLengthAttribute: Attribute{private int _maximumLength;public StringLengthAttribute(int maximumLength){_maximumLength = maximumLength;}public int MaximumLength{get { return _maximumLength; }}}public class People{[StringLength(8)]public string Name { get; set; }[StringLength(15)]public string Description { get; set; }}public class ValidationModel{public void Validate(object obj){var t = obj.GetType();//由于我们只在Property设置了Attibute,所以先获取Propertyvar properties = t.GetProperties();foreach (var property in properties){//这里只做一个stringlength的验证，这里如果要做很多验证，需要好好设计一下,千万不要用if elseif去链接//会非常难于维护，类似这样的开源项目很多，有兴趣可以去看源码。if (!property.IsDefined(typeof(StringLengthAttribute), false)) continue;var attributes = property.GetCustomAttributes(true);foreach (var attribute in attributes){//这里的MaximumLength 最好用常量去做var maxinumLength = (int)attribute.GetType().GetProperty("MaximumLength").GetValue(attribute);//获取属性的值var propertyValue = property.GetValue(obj) as string;if (propertyValue == null)throw new Exception("exception info");//这里可以自定义，也可以用具体系统异常类if (propertyValue.Length > maxinumLength)throw new Exception(string.Format("属性{0}的值{1}的长度超过了{2}", property.Name, propertyValue, maxinumLength));}}}}

        private void button1_Click(object sender, EventArgs e){var people = new People(){Name = "qwadzc",Description = "desco;o;opo;po;po;oription"};try{new ValidationModel().Validate(people);}catch (Exception ex){Console.WriteLine(ex.Message);}Console.ReadLine();}