当我们用MVVM设计模式的时候要实现INotifyPropertyChanged,每次都要实现这个接口比较麻烦,所以基类的作用就体现出来了。代码如下:
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public class ViewModelBase : INotifyPropertyChanged, IDisposable { public event PropertyChangedEventHandler PropertyChanged; public bool IsInDesignMode; /// <summary> 显示名称 </summary> public virtual string DisplayName { get ; protected set ; } #region 构造 public ViewModelBase() { } #endregion private void OnPropertyChanged( string propertyName) { if ( this .PropertyChanged != null ) { this .PropertyChanged( this , new PropertyChangedEventArgs(propertyName)); } } private static string GetProperyName( string methodName) { if (methodName.StartsWith( "get_" ) || methodName.StartsWith( "set_" ) || methodName.StartsWith( "put_" )) { return methodName.Substring(4); } throw new Exception(methodName + " not a method of Property" ); } protected void SetProperty<T>( ref T name, T value) { if ( object .Equals(name, value)) return ; name = value; string propertyName = GetProperyName( new System.Diagnostics.StackTrace( true ).GetFrame(1).GetMethod().Name); this .OnPropertyChanged(propertyName); } #region IDisposable Members public void Dispose() { this .OnDispose(); } /// <summary> /// 若支持IDisposable,请重写此方法,当被调用Dispose时会执行此方法。 /// </summary> protected virtual void OnDispose() { } #endregion } public class CommandBase : System.Windows.Input.ICommand { private Action<Object> _doWork; private readonly Func< object , bool > _canExecute; /// <summary> /// 实例化一个CommandBase对象 /// </summary> /// <param name="doWork">委托一个有object类型参数的命令执行函数</param> /// <param name="canExecute">委托一个有object类型参数的命令是否能被执行的函数(可选)</param> /// <exception cref="ArgumentNullException">参数command不可以为null引用</exception> public CommandBase(Action< object > doWork, Func< object , bool > canExecute = null ) { if (doWork == null ) throw new ArgumentNullException( "doWork" ); _canExecute = canExecute; _doWork = doWork; } public bool CanExecute(Object parameter) { return true ; } public void Execute(Object parameter) { if ( this ._doWork != null ) this ._doWork(parameter); } public event EventHandler CanExecuteChanged { add { } remove { } } } |
使用方式如下,例:
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public class TestViewModel : ViewModelBase { public TestViewModel() { this .LoadCommand = new CommandBase((Object parameter) => Loading()); } #region 属性 private string _name; /// <summary> 是否可用 </summary> public string IsEnable { get { return _name; } set { base .SetProperty< string >( ref this ._name, value); } } #endregion #region 命令 /// <summary> /// 窗口加载命令 /// </summary> public ICommand LoadCommand { get ; set ; } #endregion #region 方法 /// <summary> /// 初始化方法 /// </summary> public void Loading() { } #endregion } |