C# 表达式目录树的应用详解

public class People{public int Age { get; set; }public string Name { get; set; }public int Id;}public class PeopleCopy{public int Age { get; set; }public string Name { get; set; }public int Id;}public class Class1{private static Dictionary<string, object> _Dic = new Dictionary<string, object>();private static TOut TransExp<TIn, TOut>(TIn tIn) {string key = $"funckey_{typeof(TIn).FullName}_{typeof(TOut).FullName}";if (!_Dic.Keys.Contains(key)) { ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");List<MemberBinding> memberBindingList = new List<MemberBinding>();foreach (var item in typeof(TOut).GetProperties()){PropertyInfo propertyInfo = typeof(TIn).GetProperty(item.Name);if (propertyInfo == null) { continue; }MemberExpression property = Expression.Property(parameterExpression, propertyInfo);memberBindingList.Add(Expression.Bind(item, property));}foreach (var item in typeof(TOut).GetFields()){FieldInfo fieldInfo = typeof(TIn).GetField(item.Name);if (fieldInfo == null) { continue; }MemberExpression property = Expression.Field(parameterExpression, fieldInfo);memberBindingList.Add(Expression.Bind(item, property));}Expression<Func<TIn, TOut>> expression = Expression.Lambda<Func<TIn, TOut>>(Expression.MemberInit(Expression.New(typeof(TOut)), memberBindingList), new ParameterExpression[]{parameterExpression});Func<TIn, TOut> func = expression.Compile();_Dic.Add(key,func);}return ((Func < TIn, TOut > )_Dic[key])(tIn);}}static void Main(string[] args){List<ClassLibrary1.PeopleCopy> PeoleCopyList = new List<ClassLibrary1.PeopleCopy>();for (int i = 0; i < 5; i++){ClassLibrary1.People people = new ClassLibrary1.People() { Id = 5+1, Age = 25, Name = "aaa"+i };PeoleCopyList.Add(Class1.ToutGet<ClassLibrary1.People, ClassLibrary1.PeopleCopy>(people));}}