AOP之PostSharp4-实现类INotifyPropertyChanged植入

在前面几篇PostSharp的随笔，今天来一个简单的demo。PostSharp的其他内容将会在后面继续更新。

      如果我们了解wpf或者silverlight开发中的MVVM模式，就知道框架要求我们的ViewModel必须实现INotifyPropertyChanged，来得到属性改变的事件通知，更新UI。

实现INotifyPropertyChanged接口很简单，而且一沉不变，属于重复劳动。在这里我们将看看如何运用PostSharp来解决我们的重复劳动。当然这里只是一个demo演示，具体在项目开发中你直接实现INotifyPropertyChanged，或者AOP植入，这取决我个人和团队文化。

     在下面我们将会用到Postsharp的：

1. IntroduceMember：向目标对象植入成员。
2. IntroduceInterface：使得目标实现接口，参数接口类型。
3. OnLocationSetValueAdvice：PostSharp的一种Advice Aspect。

   下面我就看看我们的代码是如何简洁来实现：

 

using System;
using System.ComponentModel;

using PostSharp.Aspects;
using PostSharp.Aspects.Advices;
using PostSharp.Extensibility;

namespace PostSharpDemo
{
    [Serializable]
    [IntroduceInterface(typeof(INotifyPropertyChanged), OverrideAction = InterfaceOverrideAction.Ignore)]
    public class INotifyPropertyChangedAttribute : InstanceLevelAspect, INotifyPropertyChanged
    {

        [OnLocationSetValueAdvice, MulticastPointcut(Targets = MulticastTargets.Property)]
        public void OnValueChanged(LocationInterceptionArgs args)
        {
            var current=args.GetCurrentValue();
            if ((args.Value != null && (!args.Value.Equals(current)))
                || (current != null && (!current.Equals(args.Value))))
            {
                args.ProceedSetValue();
                this.OnRaisePropertyChange(args.Location.Name);
            }
        }

        #region INotifyPropertyChanged 成员

        [IntroduceMember(IsVirtual = true, OverrideAction = MemberOverrideAction.Ignore)]
        public event PropertyChangedEventHandler PropertyChanged;




        protected void OnRaisePropertyChange(string property)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged.Invoke(this.Instance, new PropertyChangedEventArgs(property));
            }
        }
        #endregion
    }

测试代码：

 

static void Main(string[] args)
        {

             Student stu = new Student();
            (stu as INotifyPropertyChanged).PropertyChanged += new PropertyChangedEventHandler(Program_PropertyChanged);
            stu.ID = 10;
            stu.Name = "wolf";
            stu.Sex = "Man";
            stu.ID = 2;
            Console.Read();
        }

        static void Program_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            Console.WriteLine(string.Format("property {0} has changed", e.PropertyName));
        }
[INotifyPropertyChanged]
   public class Student
   {
       public string Name
       { get; set; }

       public string Sex
       { get; set; }

       public int ID
       { get; set; }
   }

运行效果如下：

附件下载：demo

本博客中相关文章有：

 

• AOP之PostSharp初见-OnExceptionAspect
• AOP之PostSharp2-OnMethodBoundaryAspect
• AOP之PostSharp3-MethodInterceptionAspect
• AOP之PostSharp4-实现类INotifyPropertyChanged植入
• AOP之PostSharp5-LocationInterceptionAspect
• AOP之PostSharp6-EventInterceptionAspect
• http://www.cnblogs.com/whitewolf/category/312638.html