c# - XSD 模式到 COM 接口(interface)

Question

我必须支持旧版 Visual Basic 6.0 客户端，它需要解析 XML 文件。这些由相当大且复杂的 XSD 模式描述。为了简化解析过程，我通过 Windows SDK xsd.exe 工具创建了 C# 类，将它们添加到 C# 库项目中，并设置了“Make assembly COM-Visible”属性。不幸的是，生成的类型库没有任何值(value)，因为它只是为所有复杂类型公开了空接口(interface)。

为说明此行为，请考虑以下 XSD 架构:

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:customers" xmlns:c="urn:customers">
  <xsd:element name="catalog" type="c:CatalogData"/>   
    <xsd:complexType name="AddressData">
        <xsd:sequence>
            <xsd:element name="no" type="xsd:integer"/>
            <xsd:element name="road" type="xsd:string"/>
        </xsd:sequence>
    </xsd:complexType>
    <xsd:complexType name="CustomerData">
      <xsd:sequence>
        <xsd:element name="name" type="xsd:string"/>
        <xsd:element name="address" type="c:AddressData"/>
        <xsd:element name="order_date" type="xsd:date"/>
      </xsd:sequence>
      <xsd:attribute name="id" type="xsd:string"/>
    </xsd:complexType>
    <xsd:complexType name="CatalogData">
        <xsd:sequence>
            <xsd:element name="customer" type="c:CustomerData" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:sequence>
    </xsd:complexType>
</xsd:schema>

xsd 工具创建以下源文件:

//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:4.0.30319.34209
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

using System.Xml.Serialization;

// 
// This source code was auto-generated by xsd, Version=4.0.30319.33440.
// 


/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.33440")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="urn:customers")]
[System.Xml.Serialization.XmlRootAttribute("catalog", Namespace="urn:customers", IsNullable=false)]
public partial class CatalogData {

    private CustomerData[] customerField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute("customer", Form=System.Xml.Schema.XmlSchemaForm.Unqualified)]
    public CustomerData[] customer {
        get {
            return this.customerField;
        }
        set {
            this.customerField = value;
        }
    }
}

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.33440")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="urn:customers")]
public partial class CustomerData {

    private string nameField;

    private AddressData addressField;

    private System.DateTime order_dateField;

    private string idField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)]
    public string name {
        get {
            return this.nameField;
        }
        set {
            this.nameField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)]
    public AddressData address {
        get {
            return this.addressField;
        }
        set {
            this.addressField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="date")]
    public System.DateTime order_date {
        get {
            return this.order_dateField;
        }
        set {
            this.order_dateField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlAttributeAttribute()]
    public string id {
        get {
            return this.idField;
        }
        set {
            this.idField = value;
        }
    }
}

/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "4.0.30319.33440")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(Namespace="urn:customers")]
public partial class AddressData {

    private string noField;

    private string roadField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified, DataType="integer")]
    public string no {
        get {
            return this.noField;
        }
        set {
            this.noField = value;
        }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Form=System.Xml.Schema.XmlSchemaForm.Unqualified)]
    public string road {
        get {
            return this.roadField;
        }
        set {
            this.roadField = value;
        }
    }
}

生成的类型库如下所示:

// Generated .IDL file (by the OLE/COM Object Viewer)
// 
// typelib filename: xsd.tlb

[
]
library xsd
{

    importlib("mscorlib.tlb");

    importlib("stdole2.tlb");

    // Forward declare all types defined in this typelib
    interface _CatalogData;
    interface _CustomerData;
    interface _AddressData;

    [      
    ]
    coclass CatalogData {
        [default] interface _CatalogData;
        interface _Object;
    };

    [      
    ]
    coclass CustomerData {
        [default] interface _CustomerData;
        interface _Object;
    };

    [      
    ]
    coclass AddressData {
        [default] interface _AddressData;
        interface _Object;
    };

    [
    ]
    interface _CatalogData : IDispatch {
    };

    [
    ]
    interface _CustomerData : IDispatch {
    };

    [
    ]
    interface _AddressData : IDispatch {
    };
};

我知道，我可以手动创建所需的 COM 接口(interface)以公开所有嵌套属性。然而，由于复杂的 XSD 架构，生成的 C# 类文件超过 3000 行，我需要永远为每个部分类创建一个接口(interface)。

是否有替代方案可以加快该过程？或者有人知道另一种工具，它可以从 XSD 架构生成 COM 接口(interface)/类，最好是通过 ATL 或 C++？

Answer 1

您可能使用了“项目”>“属性”>“应用程序”>“程序集信息”按钮并勾选了“使程序集 COM 可见”选项。一种使程序集中所有具有默认构造函数的公共(public)类对 COM 客户端应用程序可见的非常快速的方法。这使用 [ClassInterface] attribute 的默认值，因为它没有明确应用于类，所以它是 ClassInterfaceType.AutoDispatch。

这是一个非常安全的设置，它有助于客户端代码对公开类中的更改更具弹性。当类更改但客户端应用程序未重新编译时，您将获得的运行时错误更易于解释。早期绑定(bind)有很多更糟糕的失败模式，包括使用完全错误的属性或客户端应用程序因 AccessViolation 异常而失败。

考虑到您公开的数据容易频繁更改，这并不是一个坏主意。

但不是您所要求的。更改默认的 [ClassInterface] 非常简单。打开 Properties > AssemblyInfo.cs 源代码文件，使其看起来像这样:

// Setting ComVisible to false makes the types in this assembly not visible 
// to COM components.  If you need to access a type in this assembly from 
// COM, set the ComVisible attribute to true on that type.
[assembly: ComVisible(true)]
[assembly: ClassInterface(ClassInterfaceType.AutoDual)]

添加了最后一行。重建您的项目，您现在将看到界面不再为空，并且自动完成功能在 VB6 IDE 中正常工作。