如何从 C# 中的字符串创建实例？
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How do I create an instance from a string in C#?
提问by Ben S
I'm reading information from an XML which contains the type of an object that I need to instantiate along with it's constructor parameters.
我正在从 XML 中读取信息，其中包含我需要实例化的对象类型及其构造函数参数。
The object type is actually in another project, within a sibling namespace. (I need to create a Company.Project2.Type within Company.Project1 class.)
对象类型实际上在另一个项目中，在同级命名空间内。（我需要在 Company.Project1 类中创建一个 Company.Project2.Type。）
I found this question, but it doesn't handle the constructor parameters or the fact that it's in another namespace.
我发现了这个问题，但它不处理构造函数参数或它在另一个命名空间中的事实。
How can I do this?
我怎样才能做到这一点？
Edit:The assembly name and default namespace wasn't set correctly in the project properties.
编辑：程序集名称和默认命名空间未在项目属性中正确设置。
采纳答案by Jon Skeet
- You need to specify the full type name to
Type.GetType(), including namespace, e.g. "Company.Project2.Type" - If the type isn't in the same assembly (or mscorlib), you need to give the assembly name too, including version information if it's strongly typed. For example, for a non-strongly typed assembly
Company.Project2.dll, you might specify "Company.Project2.Type, Company.Project2". - To call a constructor with parameters you can call
Activator.CreateInstance(Type, Object[])or get the exact constructor you want withType.GetConstructor()and then callConstructorInfo.Invoke().
- 您需要将完整的类型名称指定为
Type.GetType()，包括命名空间，例如“Company.Project2.Type” - 如果类型不在同一个程序集（或 mscorlib）中，您还需要提供程序集名称，如果它是强类型的，则包括版本信息。例如，对于非强类型程序集
Company.Project2.dll，您可以指定“Company.Project2.Type, Company.Project2”。 - 要调用带参数的构造函数，您可以调用
Activator.CreateInstance(Type, Object[])或获取所需的确切构造函数Type.GetConstructor()，然后调用ConstructorInfo.Invoke().
If that doesn't help, please give more information.
如果这没有帮助，请提供更多信息。
回答by brian chandley
If you want to create a type dynamically at run time, Activator.CreateInstance Method will do it for you. If you issue is with the type having a constructor with parameters, this overload will do this. For example, http://msdn.microsoft.com/en-us/library/wcxyzt4d.aspx
如果你想在运行时动态创建一个类型，Activator.CreateInstance 方法会为你做。如果您的问题是具有带参数的构造函数的类型，则此重载将执行此操作。例如， http://msdn.microsoft.com/en-us/library/wcxyzt4d.aspx
I advise looking through the overloads for the best match.
我建议查看重载以获得最佳匹配。
The namespace issue should be not be relavant - as long as the dll is in the bin directory or the GAC you should be OK. The rules may change if the assembly is Strongly named though.
命名空间问题不应该是相关的 - 只要 dll 在 bin 目录或 GAC 中，你应该没问题。如果程序集是强命名的，则规则可能会更改。
Could you provide a code snippiet of the code that is not working (using the method you linked to)? This + the errors you are seeing will be very helpful! [update] Quick sample using the Activator.CreateInstance that handles Constructors w/ paramaters.
您能否提供不起作用的代码的代码片段（使用您链接到的方法）？这+您看到的错误将非常有帮助！[更新] 使用 Activator.CreateInstance 处理带参数的构造函数的快速示例。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
BaseProduct b =(BaseProduct)System.Activator.CreateInstance(Type.GetType("ConsoleApplication1.Product")
,new object[]{typeof(string)},
new object[]{"123"}
);
//Activator..::.CreateInstance Method (Type, array<Object>[]()[], array<Object>[]()[])
}
}
public class Product: BaseProduct{
public Product(string id) {
}
public string Id {get;set;}
}
public abstract class BaseProduct {
abstract public string Id { get; set; }
}
}
