[.NET/C#].NET中如何使用反射通过属性名称获取对应的属性值？

问题描述

如题，在.NET开发中如何使用反射通过属性名称获取对应的属性值？

方案一

 public static object GetPropValue(object src, string propName)
 {
     return src.GetType().GetProperty(propName).GetValue(src, null);
 }

方案二

public static Object GetPropValue(this Object obj, String name) {
    foreach (String part in name.Split('.')) {
        if (obj == null) { return null; }

        Type type = obj.GetType();
        PropertyInfo info = type.GetProperty(part);
        if (info == null) { return null; }

        obj = info.GetValue(obj, null);
    }
    return obj;
}

public static T GetPropValue<T>(this Object obj, String name) {
    Object retval = GetPropValue(obj, name);
    if (retval == null) { return default(T); }

    // throws InvalidCastException if types are incompatible
    return (T) retval;
}

调用方法：

DateTime now = DateTime.Now;
int min = GetPropValue<int>(now, "TimeOfDay.Minutes");
int hrs = now.GetPropValue<int>("TimeOfDay.Hours");

方案三

使用命名空间Microsoft.VisualBasic中的Versioned.CallByName(...)方法，它使用反射可以获取属性，字段，方法，COM 对象以及动态对象等等，使用方法如下：
首先引用命名空间：

using Microsoft.VisualBasic;
using Microsoft.VisualBasic.CompilerServices;

调用方法：

Versioned.CallByName(this, "method/function/prop name", CallType.Get).ToString();

方案四

创建一个索引器，如下：

public class Foo
{
    public object this[string propertyName]
    {
        get { return this.GetType().GetProperty(propertyName).GetValue(this, null); }
        set { this.GetType().GetProperty(propertyName).SetValue(this, value, null); }
    }

    public string Bar { get; set; }
}

调用方法：

Foo f = new Foo();
// 设置值
f["Bar"] = "asdf";
// 获取值
string s = (string)f["Bar"];

方案五

public static object GetPropertyValue(object srcobj, string propertyName)
    {
        if (srcobj == null)
            return null;

        object obj = srcobj;

        // Split property name to parts (propertyName could be hierarchical, like obj.subobj.subobj.property
        string[] propertyNameParts = propertyName.Split('.');

        foreach (string propertyNamePart in propertyNameParts)
        {
            if (obj == null)    return null;

            // propertyNamePart could contain reference to specific 
            // element (by index) inside a collection
            if (!propertyNamePart.Contains("["))
            {
                PropertyInfo pi = obj.GetType().GetProperty(propertyNamePart);
                if (pi == null) return null;
                obj = pi.GetValue(obj, null);
            }
            else
            {   // propertyNamePart is areference to specific element 
                // (by index) inside a collection
                // like AggregatedCollection[123]
                //   get collection name and element index
                int indexStart = propertyNamePart.IndexOf("[")+1;
                string collectionPropertyName = propertyNamePart.Substring(0, indexStart-1);
                int collectionElementIndex = Int32.Parse(propertyNamePart.Substring(indexStart, propertyNamePart.Length-indexStart-1));
                //   get collection object
                PropertyInfo pi = obj.GetType().GetProperty(collectionPropertyName);
                if (pi == null) return null;
                object unknownCollection = pi.GetValue(obj, null);
                //   try to process the collection as array
                if (unknownCollection.GetType().IsArray)
                {
                    object[] collectionAsArray = unknownCollection as Array[];
                    obj = collectionAsArray[collectionElementIndex];
                }
                else
                {
                    //   try to process the collection as IList
                    System.Collections.IList collectionAsList = unknownCollection as System.Collections.IList;
                    if (collectionAsList != null)
                    {
                        obj = collectionAsList[collectionElementIndex];
                    }
                    else
                    {
                        // ??? Unsupported collection type
                    }
                }
            }
        }

        return obj;
    }