Question

我的问题是有没有办法使用Reflection？

检索参数列表及其值

我想使用反射从PropertyInfo中获取参数列表。

 Author author = (Author)attribute;
 string name = author.name;

不行。因为会有很多属性，这不是作者的类型。

[AttributeUsage(AttributeTargets.Class | AttributeTargets.Property,  AllowMultiple = true)]
public class Author : Attribute
{
    public Author(string name, int v)
    {
        this.name = name;
        version = v;
    }

    public double version;
    public string name;
}

public class TestClass
{
    [Author("Bill Gates", 2)]
    public TextBox TestPropertyTextBox { get; set; }
}

Answer 1

使用此程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace ConsoleApplication1 {
    class Program {
        static void Main(string[] args) {
            Console.WriteLine("Reflecting TestClass");
            foreach (var property in typeof(TestClass).GetProperties()) {
                foreach (Author author in property.GetCustomAttributes(typeof(Author), true).Cast<Author>()) {
                    Console.WriteLine("\tProperty {0} Has Author Attribute Version:{1}", property.Name, author.version);
                }
            }
            var temp = new TestClass();
            Console.WriteLine("Reflecting instance of Test class ");
            foreach (var property in temp.GetType().GetProperties()) {
                foreach (Author author in property.GetCustomAttributes(typeof(Author), true).Cast<Author>()) {
                    Console.WriteLine("\tProperty {0} Has Author Attribute Version:{1}", property.Name, author.version);
                }
            }
        }

    }

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Property, AllowMultiple = true)]
    public class Author : Attribute {
        public Author(string name, int v) {
            this.name = name;
            version = v;
        }

        public double version;
        string name;
    }

    public class TestClass {
        [Author("Bill Gates", 2)]
        public TextBox TestPropertyTextBox { get; set; }
    }

}

我得到了这个输出：

alt text

Answer 2

我假设参数列表是指所有属性用途的列表？

如果没有，此代码将向您展示如何使用整个类的反射来获取属性。但是你应该能够得到你需要的东西。

所以这是一种在TestClass

内的任何属性上查找特定类型的所有属性的方法

public IEnumberable<Result> GetAttributesFromClass(TestClass t)
{

    foreach(var property in t.GetType().GetProperties())
    {
        foreach(Author author in property.GetCustomAttributes(typeof(Arthor), true))
        {
             // now you have an author, do what you please
             var version = author.version;
             var authorName = author.name;

             // You also have the property name
             var name = property.Name;

             // So with this information you can make a custom class Result, 
             // which could contain any information from author, 
             // or even the attribute itself
             yield return new Result(name,....);
        }

    }
}

然后你可以去：

var testClass = new TestClass();

var results = GetAttributesFromClass(testClass);

此外，您可能希望public double version和string name成为属性。像这样：

public double version
{
    get; 
    private set;
}

允许从构造函数设置version，并从任何地方读取。

Answer 3

string name = author.name;

是不允许的，因为字段name不公开。如果你公开name，它会起作用吗？

Answer 4

我在其中一个应用中遇到了同样的问题。这是我的解决方案：

public static string GetAttributesData(MemberInfo member)
{            
    StringBuilder sb = new StringBuilder();
    // retrives details from all attributes of member
    var attr = member.GetCustomAttributesData();
    foreach (var a in attr)
    {
        sb.AppendFormat("Attribute Name        : {0}", a)
            .AppendLine();
        sb.AppendFormat("Constructor arguments : {0}", string.Join(",  ", a.ConstructorArguments))
            .AppendLine();
        if (a.NamedArguments != null && a.NamedArguments.Count > 0 )
        sb.AppendFormat("Named arguments       : {0}", string.Join(",  ", a.NamedArguments))
            .AppendLine();
        sb.AppendLine();
    }            
    return sb.ToString();
}

我测试了你的例子。

var t = typeof (TestClass);
var prop = t.GetProperty("TestPropertyTextBox", BindingFlags.Public | BindingFlags.Instance);
var scan = Generator.GetAttributesData(prop);

这里是输出：

Attribute Name        : [Author("Bill Gates", (Int32)2)]
Constructor arguments : "Bill Gates",  (Int32)2

使用Reflection获取属性的参数

4 个答案: