当我们用MVVM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:
class="brush:csharp;gutter:true;"> 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:
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 }
看了例子后,是不是感觉很简单呢?详细的测试代码会再后续的文章中提供给大家参考。