blocks|key|522665|text|进行这种运行时评估的最简单方法是使用Reflection。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|522666|根据您使用的.NET版本，您可以向类添加方法或使用扩展方法。|522667|entityMap|0|LINK|mutability|MUTABLE|url|http://www.devx.com/vb2themax/Tip/19598^0|I|A|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

The easiest way to do this kind of runtime evaluation is with <a href="http://www.devx.com/vb2themax/Tip/19598" rel="nofollow noreferrer">Reflection</a>.

Depending on the version of .NET you're using, you could add methods to your class or use extension methods.

blocks|key|522648|text|之前回答了一个类似的问题。这是一个代码示例，并链接到另一个问题。Hiding+Public+Functions|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|522649|您最感兴趣的将是System.Reflection.PropertyInfo类的GetValue方法。|522650|C#代码示例|522651|public+bool+SetProperty(object+obj,+string+PropertyName,+object+val)
{
 + +object+property_value+=+null;
 + +System.Reflection.PropertyInfo[]+properties_info+=+obj.GetType.GetProperties;
 + +System.Reflection.PropertyInfo+property_info+=+default(System.Reflection.PropertyInfo);
 + +
 + +foreach+(System.Reflection.PropertyInfo+prop+in+properties_info)+{
 + + + +if+(prop.Name+==+PropertyName)+property_info+=+prop;+
 + +}
 + +
 + +if+(property_info+!=+null)+{
 + + + +try+{
 + + + + + +property_info.SetValue(obj,+val,+null);
 + + + + + +return+true;
 + + + +}
 + + + +catch+(Exception+ex)+{
 + + + + + +return+false;
 + + + +}
 + +}
 + +else+{
 + + + +return+false;
 + +}
}

public+object+GetProperty(object+obj,+string+PropertyName)
{
 + +object+property_value+=+null;
 + +System.Reflection.PropertyInfo[]+properties_info+=+obj.GetType.GetProperties;
 + +System.Reflection.PropertyInfo+property_info+=+default(System.Reflection.PropertyInfo);
 + +
 + +foreach+(System.Reflection.PropertyInfo+prop+in+properties_info)+{
 + + + +if+(prop.Name+==+PropertyName)+property_info+=+prop;+
 + +}
 + +
 + +if+(property_info+!=+null)+{
 + + + +try+{
 + + + + + +property_value+=+property_info.GetValue(obj,+null);
 + + + + + +return+property_value;
 + + + +}
 + + + +catch+(Exception+ex)+{
 + + + + + +return+null;
 + + + +}
 + +}
 + +else+{
 + + + +return+null;
 + +}
}|code-block|syntax|javascript|522652|VB代码示例|522653|Public+Function+SetProperty(ByVal+obj+As+Object,+ByVal+PropertyName+As+String,+ByVal+val+As+Object)+As+Boolean
++++Dim+property_value+As+Object
++++Dim+properties_info+As+System.Reflection.PropertyInfo()+=+obj.GetType.GetProperties
++++Dim+property_info+As+System.Reflection.PropertyInfo

++++For+Each+prop+As+System.Reflection.PropertyInfo+In+properties_info
++++++++If+prop.Name+=+PropertyName+Then+property_info+=+prop
++++Next

++++If+property_info+IsNot+Nothing+Then
++++++++Try
++++++++++++property_info.SetValue(obj,+val,+Nothing)
++++++++++++Return+True
++++++++Catch+ex+As+Exception
++++++++++++Return+False
++++++++End+Try
++++Else
++++++++Return+False
++++End+If
End+Function

Public+Function+GetProperty(ByVal+obj+As+Object,+ByVal+PropertyName+As+String)+As+Object
++++Dim+property_value+As+Object
++++Dim+properties_info+As+System.Reflection.PropertyInfo()+=+obj.GetType.GetProperties
++++Dim+property_info+As+System.Reflection.PropertyInfo

++++For+Each+prop+As+System.Reflection.PropertyInfo+In+properties_info
++++++++If+prop.Name+=+PropertyName+Then+property_info+=+prop
++++Next

++++If+property_info+IsNot+Nothing+Then
++++++++Try
++++++++++++property_value+=+property_info.GetValue(obj,+Nothing)
++++++++++++Return+property_value
++++++++Catch+ex+As+Exception
++++++++++++Return+Nothing
++++++++End+Try
++++Else
++++++++Return+Nothing
++++End+If
End+Function|522654|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1754516/hiding-public-functions/1755672#1755672|1|http://msdn.microsoft.com/en-us/library/system.reflection.propertyinfo.getvalue.aspx^0|W|N|0|0|14|8|1|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]]|C|$]]|$1|D|3|E|5|6|7|14|8|@]|9|@$A|15|B|16|1|17]]|C|$]]|$1|F|3|G|5|6|7|18|8|@]|9|@]|C|$]]|$1|H|3|I|5|J|7|19|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1A|8|@]|9|@]|C|$]]|$1|O|3|P|5|J|7|1B|8|@]|9|@]|C|$K|L]]|$1|Q|3|-4|5|6|7|1C|8|@]|9|@]|C|$]]]|R|$S|$5|T|U|V|C|$W|X]]|Y|$5|T|U|V|C|$W|Z]]]]

Answered a similar question earlier. Here's a code sample, and link to the other question.
<a href="https://stackoverflow.com/questions/1754516/hiding-public-functions/1755672#1755672">Hiding Public Functions</a>

You're going to be most interested in the <a href="http://msdn.microsoft.com/en-us/library/system.reflection.propertyinfo.getvalue.aspx" rel="nofollow noreferrer">GetValue</a> method of the System.Reflection.PropertyInfo class.

C# Code Sample

<pre><code>public bool SetProperty(object obj, string PropertyName, object val)
{
    object property_value = null;
    System.Reflection.PropertyInfo[] properties_info = obj.GetType.GetProperties;
    System.Reflection.PropertyInfo property_info = default(System.Reflection.PropertyInfo);
    
    foreach (System.Reflection.PropertyInfo prop in properties_info) {
        if (prop.Name == PropertyName) property_info = prop; 
    }
    
    if (property_info != null) {
        try {
            property_info.SetValue(obj, val, null);
            return true;
        }
        catch (Exception ex) {
            return false;
        }
    }
    else {
        return false;
    }
}

public object GetProperty(object obj, string PropertyName)
{
    object property_value = null;
    System.Reflection.PropertyInfo[] properties_info = obj.GetType.GetProperties;
    System.Reflection.PropertyInfo property_info = default(System.Reflection.PropertyInfo);
    
    foreach (System.Reflection.PropertyInfo prop in properties_info) {
        if (prop.Name == PropertyName) property_info = prop; 
    }
    
    if (property_info != null) {
        try {
            property_value = property_info.GetValue(obj, null);
            return property_value;
        }
        catch (Exception ex) {
            return null;
        }
    }
    else {
        return null;
    }
}
</code></pre>

VB Code Sample

<pre><code>Public Function SetProperty(ByVal obj As Object, ByVal PropertyName As String, ByVal val As Object) As Boolean
 Dim property_value As Object
 Dim properties_info As System.Reflection.PropertyInfo() = obj.GetType.GetProperties
 Dim property_info As System.Reflection.PropertyInfo

 For Each prop As System.Reflection.PropertyInfo In properties_info
 If prop.Name = PropertyName Then property_info = prop
 Next

 If property_info IsNot Nothing Then
 Try
 property_info.SetValue(obj, val, Nothing)
 Return True
 Catch ex As Exception
 Return False
 End Try
 Else
 Return False
 End If
End Function

Public Function GetProperty(ByVal obj As Object, ByVal PropertyName As String) As Object
 Dim property_value As Object
 Dim properties_info As System.Reflection.PropertyInfo() = obj.GetType.GetProperties
 Dim property_info As System.Reflection.PropertyInfo

 For Each prop As System.Reflection.PropertyInfo In properties_info
 If prop.Name = PropertyName Then property_info = prop
 Next

 If property_info IsNot Nothing Then
 Try
 property_value = property_info.GetValue(obj, Nothing)
 Return property_value
 Catch ex As Exception
 Return Nothing
 End Try
 Else
 Return Nothing
 End If
End Function
</code></pre>

blocks|key|522722|text|item.GetProperties()将返回一个包含所有属性的PropertyInfo[]+(我认为只能是公共的)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|522723|PropertyInfo对象有一个属性名，该属性名就是该属性的名称，因此可以遍历数组，使用搜索名称搜索PropertyInfo对象。|522724|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

item.GetProperties() would return a PropertyInfo[] containing all properties (public only I think)

A PropertyInfo Object has a property Name which is the name of the property, so you can iterate over the array searching for a PropertyInfo object with your search name.

blocks|key|511998|text|如果您知道对象的类型，则可以使用反射获取所有属性，然后获取请求的属性。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|511999|MyClass+o;

PropertyInfo[]+properties+=+o.GetType().GetProperties(
++++BindingFlags.NonPublic+%7C+BindingFlags.Public+%7C+BindingFlags.Instance);|code-block|syntax|javascript|512000|每个PropertyInfo都有一个名称，您可以将其与字符串相匹配。|512001|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you know the type of object you can get all the properties, and then your requested property, using reflection.

<pre><code>MyClass o;

PropertyInfo[] properties = o.GetType().GetProperties(
 BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance);
</code></pre>

Each PropertyInfo has a Name which you can match up to your String.

blocks|key|1822216|text|编辑：我刚刚读到了你关于不使用开关的评论，但我还是会把它放在这里，以防万一……跳到我的第二个答案。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1822217|可能是这样的：|1822218|public+enum+Property+{+Name,+Age,+DateOfBirth};

public+T+GetProperty<T>(Property+property)
{
++++switch+(property)
++++{
+++++++case+Property.Name:
++++++++++return+this.Name;
+++++++//+etc.
++++}
}|code-block|syntax|javascript|1822219|我对遗传学不是很在行，所以也许有人可以帮我处理回归的角色。|1822220|1822221|或者，您可以将一个字段添加到DataRow类型的类中，并使用索引器访问它：|1822222|public+class+MyClass
{
+++DataTable+myRow+=+null;
+++MyClass(DataRow+row)
+++{
++++++myRow+=+row;
+++}

+++public+object+this[string+name]
+++{
++++++get
++++++{
+++++++++return+this.myRow[name];
++++++}
++++++set
++++++{
+++++++++this.myRow[name]+=+value;
++++++}
+++}
}|1822223|用法：|1822224|MyClass+c+=+new+MyClass(table.Rows[0]);
string+name+=+c["Name"].ToString();|1822225|entityMap^0|0|3|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|12|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|13|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|14|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]|$1|P|3|Q|5|6|7|16|8|@]|D|@]|E|$]]|$1|R|3|S|5|J|7|17|8|@]|D|@]|E|$K|L]]|$1|T|3|U|5|6|7|18|8|@]|D|@]|E|$]]|$1|V|3|W|5|J|7|19|8|@]|D|@]|E|$K|L]]|$1|X|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|Y|$]]

EDIT: I just read your comment about not using a switch, but I'll keep this here anyway, just in case... skip to my second answer.

Maybe something like this:

<pre><code>public enum Property { Name, Age, DateOfBirth};

public T GetProperty&lt;T&gt;(Property property)
{
 switch (property)
 {
 case Property.Name:
 return this.Name;
 // etc.
 }
}
</code></pre>

I'm not too strong in Genetics, so maybe someone can help me with the return cast.

<hr>

Alternatively, you could add a field to your class of type DataRow and use an indexer to access it:

<pre><code>public class MyClass
{
 DataTable myRow = null;
 MyClass(DataRow row)
 {
 myRow = row;
 }

 public object this[string name]
 {
 get
 {
 return this.myRow[name];
 }
 set
 {
 this.myRow[name] = value;
 }
 }
}
</code></pre>

Usage:

<pre><code>MyClass c = new MyClass(table.Rows[0]);
string name = c["Name"].ToString();
</code></pre>

blocks|key|512065|text|string+propertyToGet+=+"SomeProperty";
SomeClass+anObject+=+new+SomeClass();

string+propertyValue+=+
++++(string)typeof(SomeClass)
++++.GetProperty("SomeProperty")
++++.GetValue(anObject,+null);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|512066|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>string propertyToGet = "SomeProperty";
SomeClass anObject = new SomeClass();

string propertyValue = 
 (string)typeof(SomeClass)
 .GetProperty("SomeProperty")
 .GetValue(anObject, null);
</code></pre>

blocks|key|512073|text|使用indexers的示例|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|512074|public+class+MyItem
{
++++public+object+this[string+name]
++++{
++++++++switch+(name)
++++++++{
++++++++++++case+"Name":
++++++++++++++++return+"Wikipetan";
++++++++++++case+"Age":
++++++++++++++++return+8;
++++++++++++case+"DateOfBirth":
++++++++++++++++return+new+DateTime(2001,+01,+15);
++++++++++++case+"Baka":
++++++++++++++++return+false;
++++++++++++default:
++++++++++++++++throw+new+ArgumentException();
++++++++}
++++}
}|code-block|syntax|javascript|512075|用法：|512076|MyItem+item+=+...;
string+propertyName+=+"Age";
int+age+=+(int)item[propertyName];|512077|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx^0|2|8|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Example using <a href="http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx" rel="nofollow noreferrer">indexers</a>:

<pre><code>public class MyItem
{
 public object this[string name]
 {
 switch (name)
 {
 case "Name":
 return "Wikipetan";
 case "Age":
 return 8;
 case "DateOfBirth":
 return new DateTime(2001, 01, 15);
 case "Baka":
 return false;
 default:
 throw new ArgumentException();
 }
 }
}
</code></pre>

Usage:

<pre><code>MyItem item = ...;
string propertyName = "Age";
int age = (int)item[propertyName];
</code></pre>

Let's say I have a class that has 3 properties. I don't know which property I want to read until runtime. Is there a way to do this without a switch/if-else statement?

If a DataTable is treated as a class, then the columns can be treated dynamically which would work, but I'm not able to change my class into a DataTable (long story).

For a DataTable, the code would be:

<pre><code>string columnName = "Age";
int age = dataRow[columnName];
</code></pre>

How is this possible in a class?

<pre><code>string propertyName = "Baka";
int age = item.getProperty(propertyName) // ???
</code></pre>

Question about reading properties of a class at run time in c# (.NET 2.0)?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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假设我有一个有3个属性的类。直到运行时我才知道要读取哪个属性。有没有办法在不使用switch/if-else语句的情况下做到这一点？如果将DataTable视为一个类，那么可以动态地处理列，这是可行的，但我无法将我的类更改为DataTable (长篇大论)。对于DataTable，代码为：string columnNa...

问关于在c# (.NET 2.0)中在运行时读取类的属性的问题？
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问关于在c# (.NET 2.0)中在运行时读取类的属性的问题？EN