C＃中的Type.FindMembers()方法与示例

Type.FindMembers(MemberTypes，BindingFlags，MemberFilter，Object)方法用于返回指定成员类型的MemberInfo对象的过滤数组。

句法：

public virtual System.Reflection.MemberInfo[] FindMembers (System.Reflection.MemberTypes memberType, System.Reflection.BindingFlags bindingAttr, System.Reflection.MemberFilter filter, object filterCriteria);

参数：

• memberType：表示要搜索的成员类型。
• bindingAttr：用于指定进行搜索的方式或为零，以返回null。
• filter：进行比较，如果当前正在检查的成员与filterCriteria相匹配，则返回true，否则返回false。
• filterCriteria：确定是否在MemberInfo对象数组中返回成员的搜索条件。

以下BindingFlags过滤器标志可用于定义要在搜索中包括的成员：

• 您必须指定BindingFlags.Instance或BindingFlags.Static才能获得回报。
• 指定BindingFlags.Instance以在搜索中包括实例成员。
• 指定BindingFlags.Static以在搜索中包括静态成员。
• 指定BindingFlags.Public以在搜索中包括公共成员。
• 指定BindingFlags.NonPublic以在搜索中包括非公共成员(即私有成员，内部成员和受保护成员)。

返回值：该方法返回指定成员类型的MemberInfo对象的过滤数组。或类型为MemberInfo的空数组，

异常：如果filter为null，则此方法将引发ArgumentNullException 。

例子：

// C# program to demonstrate the
// Type.FindMembers(MemberTypes, 
// BindingFlags, MemberFilter, 
// Object) Method
using System;
using System.Globalization;
using System.Reflection;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
        // Declaring and intializing object of Type
        Type objType = typeof(string);
  
        // Creating try-catch block for handling Exception
        try {
  
            // Declaring and initializing the object of MemberTypes
            // that indicates the type of member to search for.
            MemberTypes mt = MemberTypes.All;
  
            // Declaring and initializing the object of BindingFlags
            // that specify how the search is conducted.
            BindingFlags ba = BindingFlags.Public
                          | BindingFlags.Instance;
  
            // Declaring and intializing MemberFilter
            // which help the delegate that compares
            // the MemberInfo against filterCriteria.
            MemberFilter mf = new MemberFilter(Search);
  
            // Declaring and intializing object of filterCriteria
            // the search criteria that determines whether a member is
            // returned in the array of MemberInfo objects or not
            object filterCriteria = "Equals";
  
            // Getting filterd array of MemberInfo by
            // using FindMembers() Method
            MemberInfo[] info = objType.FindMembers(mt, ba, mf, filterCriteria);
  
            // Display the Result
            for (int index = 0; index < info.Length; index++)
                Console.WriteLine("Result of FindMembers -  {0}",
                                        info[index].ToString());
        }
  
        // catch ArgumentNullException here
        catch (ArgumentNullException e) 
        {
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
  
    // Defining MyInterfaceFilter
    // which helps to fix the certain condition
    // on which filtration took place
    public static bool Search(MemberInfo info, Object obj)
    {
  
        // Compare the name of the member
        // function with the filter criteria.
        if (info.Name.ToString() == obj.ToString())
            return true;
        else
            return false;
    }
}

输出：

Result of FindMembers -  Boolean Equals(System.Object)
Result of FindMembers -  Boolean Equals(System.String)
Result of FindMembers -  Boolean Equals(System.String, System.StringComparison)

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.type.findmembers?view=netcore-3.0