如何从字符串表示中获取泛型类型？

Question

我有MyClass<T>.

然后我有了这个string s = "MyClass<AnotherClass>";.如何从字符串中获取Type s？

一种方法(丑陋)是解析"<"和">"并执行:

Type acType = Type.GetType("AnotherClass");  
Type whatIwant = typeof (MyClass<>).MakeGenericType(acType);

但有没有更简洁的方法来获得最终类型,没有任何解析等？

Answer 1

泛型的格式是名称,`字符,类型参数的数量,后面是逗号分隔的括号中的类型列表:

Type.GetType("System.Collections.Generic.IEnumerable`1[System.String]");

我不确定是否有一种简单的方法可以将泛型的C#语法转换为CLR想要的字符串.我开始编写一个快速正则表达式来解析它,就像你在问题中提到的那样,但是我意识到除非你放弃将嵌套泛型作为类型参数的能力,否则解析会变得非常复杂.

Answer 2

退房Activator.CreateInstance- 你可以用一种类型来打电话

Activator.CreateInstance(typeof(MyType))

或者使用程序集和类型名称 string

Activator.CreateInstance("myAssembly", "myType")

这将为您提供所需类型的实例.

如果您需要Type而不是实例,请使用Type.GetType()您感兴趣的类型的方法和完全限定名称,例如:

string s = "System.Text.StringBuilder";
Type myClassType = Type.GetType(s);

这会给你带来Type问题.

Answer 3

我需要这样的东西,最后我编写了一些代码来解析我需要的简单类型名称.当然有改进的余地,因为它不会识别泛型类型的名称,如List<string>,但它确实蛮好的string,int[],decimal?和这样的.分享以防万一这有助于任何人.

public static class TypeExtensions
{
  public static Type GetTypeFromSimpleName(string typeName)
  {
    if (typeName == null)
      throw new ArgumentNullException("typeName");

    bool isArray = false, isNullable = false;

    if (typeName.IndexOf("[]") != -1)
    {
      isArray = true;
      typeName = typeName.Remove(typeName.IndexOf("[]"), 2);
    }

    if (typeName.IndexOf("?") != -1)
    {
      isNullable = true;
      typeName = typeName.Remove(typeName.IndexOf("?"), 1);
    }

    typeName = typeName.ToLower();

    string parsedTypeName = null;
    switch (typeName)
    {
      case "bool":
      case "boolean":
        parsedTypeName = "System.Boolean";
        break;
      case "byte":
        parsedTypeName = "System.Byte";
        break;
      case "char":
        parsedTypeName = "System.Char";
        break;
      case "datetime":
        parsedTypeName = "System.DateTime";
        break;
      case "datetimeoffset":
        parsedTypeName = "System.DateTimeOffset";
        break;
      case "decimal":
        parsedTypeName = "System.Decimal";
        break;
      case "double":
        parsedTypeName = "System.Double";
        break;
      case "float":
        parsedTypeName = "System.Single";
        break;
      case "int16":
      case "short":
        parsedTypeName = "System.Int16";
        break;
      case "int32":
      case "int":
        parsedTypeName = "System.Int32";
        break;
      case "int64":
      case "long":
        parsedTypeName = "System.Int64";
        break;
      case "object":
        parsedTypeName = "System.Object";
        break;
      case "sbyte":
        parsedTypeName = "System.SByte";
        break;
      case "string":
        parsedTypeName = "System.String";
        break;
      case "timespan":
        parsedTypeName = "System.TimeSpan";
        break;
      case "uint16":
      case "ushort":
        parsedTypeName = "System.UInt16";
        break;
      case "uint32":
      case "uint":
        parsedTypeName = "System.UInt32";
        break;
      case "uint64":
      case "ulong":
        parsedTypeName = "System.UInt64";
        break;
    }

    if (parsedTypeName != null)
    {
      if (isArray)
        parsedTypeName = parsedTypeName + "[]";

      if (isNullable)
        parsedTypeName = String.Concat("System.Nullable`1[", parsedTypeName, "]");
    }
    else
      parsedTypeName = typeName;

    // Expected to throw an exception in case the type has not been recognized.
    return Type.GetType(parsedTypeName);
  }
}

使用它就像写这个一样简单:

Type t;

t = TypeExtensions.GetTypeFromSimpleName("string");
t = TypeExtensions.GetTypeFromSimpleName("int[]");
t = TypeExtensions.GetTypeFromSimpleName("decimal?");