CSharp-复制对象的方式

在代码中经常会遇到需要把对象复制一遍，或者把属性名相同的值复制一遍。

解决方法

以People为例

public class People
{
    public string IdCard { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
}

1. 手动赋值

   People p = new People() {IdCrad = "445221XXXXXXXX", Name="caty", Age=21 };
   People h = new People() {IdCrad = p.IdCard, Name = p.Name, Age = p.Age };

2. 反射

   private static TOut TransReflection<TIn, TOut>(TIn tIn)
   {
       TOut tOut = Activator.CreateInstance<TOut>();
       var tInType = tIn.GetType();
       foreach (var itemOut in tOut.GetType().GetProperties())
       {
           var itemIn = tInType.GetProperty(itemOut.Name); ;
           if (itemIn != null)
           {
               itemOut.SetValue(tOut, itemIn.GetValue(tIn));
           }
       }
       return tOut;
   }
   
   People pp = TransReflection<People, People>(p);

3. 序列化
   需引入Newtonsoft. Json 包

   People ss= JsonConvert.DeserializeObject<People>(JsonConvert.SerializeObject(s));

4. 表达式树

   public static class TransExpression<TIn, TOut>
   {
       private static readonly Func<TIn, TOut> cache = GetFunc();
       private static Func<TIn, TOut> GetFunc()
       {
           ParameterExpression parameterExpression = Expression.Parameter(typeof(TIn), "p");
           List<MemberBinding> memberBindingList = new List<MemberBinding>();
           foreach (var item in typeof(TOut).GetProperties())
           {
   　　　　　　　if (!item.CanWrite)
   　　　　　　　　    continue;
               MemberExpression property = Expression.Property(parameterExpression, typeof(TIn).GetProperty(item.Name));
               MemberBinding memberBinding = Expression.Bind(item, property);
               memberBindingList.Add(memberBinding);
           }
   
           MemberInitExpression memberInitExpression = Expression.MemberInit(Expression.New(typeof(TOut)), memberBindingList.ToArray());
           Expression<Func<TIn, TOut>> lambda = Expression.Lambda<Func<TIn, TOut>>(memberInitExpression, new ParameterExpression[] { parameterExpression });
           return lambda.Compile();
       }
   
       public static TOut Trans(TIn tIn)
       {
           return cache(tIn);
       }
   }
   
   People pp = TransExpression<People,People>,Trans(p);