Delphi 6 含有许多更新更强的XML支持功能，增加了XML文件编程，XML数据绑定向导，XML映象和BizSnap(SOAP/XML Web服务)。我在上一篇文章论述了Delphi 6中的XML文件编程(XML Document Programming)。本文是三篇论述Delphi 6中XML功能系列文章的第二篇，论述Delphi 6中的XML数据绑定(XML Data Binding)。

XML文件编程
XMLDocument组件让我们能够遍历和编辑XML文件。但是在上一篇文章中我提到了，我们只能与无类型节点打交道，必须记住节点元素的名字。这意味着无法进行实时编译调试！幸亏的是，如果Delphi只能处理这样简单的问题就不成其为Delphi了。运用XML的内容相关结构可以做更高级的应用，这就是Delphi 6的XML数据绑定向导(XML Data Binding Wizard)。

XML数据绑定
在Delphi 6的模块仓库(Object Repository)中可以找到XML数据绑定向导(XML Data Binding Wizard)。程序员能够用它生成相应的接口和类来访问与修改XML文件数据，诸如ClientDataSetXML数据，ADO XML数据，其它XML文件数据(如我们在前文用到的Clinic.xml，本文继续使用这个简单的XML文件作示例)。

现在开始吧，启动Delphi 6，在主菜单上选择File | New - Other，然后在仓库中选择XML Data Binding，如图1所示。

向导有三个页面。第一页定义XML纲(Schema)或XML文件(本例用Clinic.xml)，如图2所示。
在资源输入框内输入XML纲(Schema)或XML文件。“选项”(Options)对话框定义编码选项和数据类型映射关系(Data Type map)。以后我们还会谈到这些选项。

向导的第二页显示了树结构和节点数据类型(亦即向导生成了些什么样的代码)。图3可以看到我的XML文件结构。
可以看到XML文件里描述的嵌套节点(ClinicsType与ClinicType)和单节点(String)。这时可以打开选项(Options)对话框(图4)，修改编码(比如修改前缀)和数据类型映射。

向导的第三页显示生成的相应接口和类。可以把这些结果保存到文件(例如生成Clinic.xdb)。
结果(存储为Clinic.xdb文件)显示如下。我们得到一个ClinicsType类型的Clinics元素，其中包括ClinicType类型的Clinic系列元素。

  <?xml version="1.0"?>
  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
  xmlns:xdb="http://www.borland.com/schemas/delphi/6.0/XMLDataBinding">
    <xs:element name="Clinics" type="ClinicsType"/>
    <xs:complexType name="ClinicsType">
      <xs:annotation>
        <xs:appinfo xdb:docElement="Clinics"/>
      </xs:annotation>
      <xs:sequence>
        <xs:element name="Clinic" type="ClinicType" maxOccurs="unbounded"/>
      </xs:sequence>
    </xs:complexType>
    <xs:complexType name="ClinicType">
      <xs:sequence>
        <xs:element name="Title" type="xs:string"/>
        <xs:element name="Date" type="xs:string"/>
        <xs:element name="Topics" type="xs:string"/>
      </xs:sequence>
      <xs:attribute name="No" type="xs:string"/>
    </xs:complexType>
  </xs:schema>

文件同时定义ClinicType类型的Clinic元素包含一系列字符串元素(Title, Date和Topics)。

生成代码
向导生成的代码可以直接在应用中使用。不幸的是，Delphi 6有时会产生“非法操作”的出错信息。重新执行一遍，它又能工作了。
以下是生成的代码(Clinic.pas)：

  {****************************************************}
  {                                                    }
  {              Delphi XML Data Binding               }
  {                                                    }
  {         Generated on: 2001/11/07 00:37:00          }
  {       Generated from: D:D6ClinicsrcClinic.xml   }
  {   Settings stored in: D:D6ClinicsrcClinic.xdb   }
  {                                                    }
  {****************************************************}
  unit Clinic;
  interface
  uses xmldom, XMLDoc, XMLIntf;

  type

  { Forward Decls }

    IXMLClinicsType = interface;
    IXMLClinicType = interface;

  { IXMLClinicsType }

  IXMLClinicsType = interface(IXMLNodeCollection)
    ['{06723E03-662D-11D5-81CE-00104BF89DAD}']
    { Property Accessors }
    function Get_Clinic(Index: Integer): IXMLClinicType;
    { Methods & Properties }
    function Add: IXMLClinicType;
    function Insert(const Index: Integer): IXMLClinicType;
    property Clinic[Index: Integer]: IXMLClinicType
      read Get_Clinic; default;
  end;

  { IXMLClinicType }

  IXMLClinicType = interface(IXMLNode)
    ['{06723E04-662D-11D5-81CE-00104BF89DAD}']
    { Property Accessors }
    function Get_No: WideString;
    function Get_Title: WideString;
    function Get_Date: WideString;
    function Get_Topics: WideString;
    procedure Set_No(Value: WideString);
    procedure Set_Title(Value: WideString);
    procedure Set_Date(Value: WideString);
    procedure Set_Topics(Value: WideString);
    { Methods & Properties }
    property No: WideString read Get_No write Set_No;
    property Title: WideString read Get_Title write Set_Title;
    property Date: WideString read Get_Date write Set_Date;
    property Topics: WideString read Get_Topics write Set_Topics;
  end;

  { Forward Decls }

    TXMLClinicsType = class;
    TXMLClinicType = class;

  { TXMLClinicsType }

  TXMLClinicsType = class(TXMLNodeCollection, IXMLClinicsType)
  protected
    { IXMLClinicsType }
    function Get_Clinic(Index: Integer): IXMLClinicType;
    function Add: IXMLClinicType;
    function Insert(const Index: Integer): IXMLClinicType;
  public
    procedure AfterConstruction; override;
  end;

  { TXMLClinicType }

  TXMLClinicType = class(TXMLNode, IXMLClinicType)
  protected
    { IXMLClinicType }
    function Get_No: WideString;
    function Get_Title: WideString;
    function Get_Date: WideString;
    function Get_Topics: WideString;
    procedure Set_No(Value: WideString);
    procedure Set_Title(Value: WideString);
    procedure Set_Date(Value: WideString);
    procedure Set_Topics(Value: WideString);
  end;

  { Global Functions }

  function GetClinics(Doc: IXMLDocument): IXMLClinicsType;
  function LoadClinics(const FileName: WideString): IXMLClinicsType;
  function NewClinics: IXMLClinicsType;

这里有二个接口类型：IXMLClinicsType和IXMLClinicType；用二个类(TXMLClinicsType和TXMLClinicType)来执行这二个接口。另外还有三个全局函数：GetClinics (获得根元素)，LoadClinics (从外部XML文件加载)和NewClinics (在内存生成新文件)。

用法
使用生成的Clinic.pas单元是很容易的。跟前一篇文章的做法一样，使用XMLDocument组件(在Inernet标签内)。不过我们不再使用无类型节点了，我们可以调用GetClinics函数获得IXMLClinicsType类型。以下是具体操作过程：

在Delphi 6建立一个新的应用(project)
在XML数据绑定向导指引下建立Clinic.pas文件(经过命名存盘 - 译者)
在主窗体上加入一个XMLDocument组件，其FileName属性为Clinic.xml
在主窗体的OnCreate事件中加入以下代码：
  procedure TForm1.FormCreate(Sender: TObject);
  var
    Clinics: IXMLClinicsType;
  begin
    Clinics := GetClinics(XMLDocument1);
  end;

把Clinics变量放到主窗体中是很有用的，这样就可以在主窗体运行期间使用Clinics接口。使用IXMLClinicsType变量类型要比以前使用普通XMLDocument组件方便多了。现在可以通过Get_Clinic方法来获得各个Clinic元素，还可以在特定位置插入新的Clinic元素。用Clinics.Clinic可以获得节点元素，用Getter和Setter方法可以得到或设置元素值。现在可以直接访问No, Title, Date, Topics等属性了：
  procedure TForm1.ButtonGetClick(Sender: TObject);
  var
    Clinic: IXMLClinicType;
  begin
    Clinic := Clinics.Clinic[0];
    EditNo.Text := Clinic.No;
    EditTitle.Text := Clinic.Title;
    EditDate.Text := Clinic.Date;
    EditTopics.Text := Clinic.Topics
  end;

可以在Clinic.pas中看到，Getter和Setter是方法而不是属性(实际上，我始终认为使用属性更清楚些)。但是Delphi 6让你看到的却是属性描述而不是方法本身(Delphi 6的另一个受欢迎的优点)。将上面这段代码与前一篇文章使用的方法相比较，就能感到操作方便多了。

下面的例子在XML树的末尾加入一个节点：
  procedure TForm1.ButtonAddClick(Sender: TObject);
  begin
    with Clinics.Add do
    begin
      No := '2001-2-8;  // 8th Clinic of the 2nd series of 2001
      Title := 'Special Kylix 2 Clinic';
      Date := '2001/12/21';
      Topics := 'Kylix 2 New Features'
    end
  end;

如果没有把XMLDocument组件的AutoSave设置为真，可以用以下方法保存更动结果：
  procedure TForm1.FormDestroy(Sender: TObject);
  begin
    XMLDocument1.SaveToFile;
  end;

这就是XML数据绑定向导，一个非常方便的方法。它能做得越来越好。

下一篇文章：
我们已经看到了XML数据绑定的优点。不过好象还有点不“满足”，比方要遍历各个节点，存取节点值(不单单是字符串类型)，虽然可用选项决定，但还是用Delphi 6的XML映象更好，它的功能更强。我们将在下一篇文章论述。

下面文章摘于http://community.borland.com/article/0,1410,28631,00.html

Use ADO.NET datasets in Delphi
Ratings: be the first!  Rate It

Abstract: Learn how to use ADO.NET datasets in Delphi, using XML mapper to transform XML across the platforms. Demonstrated using a .NET web service and Delphi client. 

Use ADO.NET Datasets in Delphi

Introduction

If you've experimented with Web Services, you might have hit some Microsoft .NET based Web Services which return data all right, but it's in the default XML format from ADO.NET. So you end up with some XML but you have no clue what to do with it! This article explains how you can take this XML, make sense out of it and even display it in a DB Grid.

Scope

I'm not going to explain much about .NET, or the ADO.NET XML format. What I'll talk about is the most probable case you'll encounter .NET datasets: as XML returned from a .NET based Web Service. If you're going to use .NET datasets in some other way, you might want to read this article to get an idea of how to make your Delphi application aware of them.

Hitting the .NET service

Let's start with a simple .NET service, as given in http://services.pagedownweb.com/ZipCodes.asmx. I've used the Web Service Importer in File | New | Other | Web Services and generated the Pascal files. Here's the declaration that looks odd:

  rtnZipDSResult = class(TRemotable)
  private
    Fs_schema: String;
  published
    property s_schema: String read Fs_schema write Fs_schema;
  end;

  ZipCodesSoap = interface(IInvokable)
  ['{FEF279A0-29EE-CF0B-FBB2-7DD79A5502CE}']
    ...
	function  rtnZipDS(const City_IN: String; const State_IN: String): rtnZipDSResult; stdcall;
	...
  end;

Using the .NET service in Delphi

I've created a sample form , which looks like this:

Now we've setup the HTTPRio, and the code behind the Get Zip Codes button is:

procedure TForm1.Button1Click(Sender: TObject);
begin
  (HTTPRIO1 as ZipCodesSoap).rtnZipDS(edtCity.Text, edtState.Text);
end;

procedure TForm1.HTTPRIO1AfterExecute(const MethodName: String;
  SOAPResponse: TStream);
begin
  SOAPResponse.Position := 0;
  Memo1.Lines.LoadFromStream(SOAPResponse);

  SOAPResponse.Position := 0;
end;

Interpreting the .NET XML

We have to figure out how to get Delphi to USE this data. We would like to have a Client Data Set read the XML so we can display it all in a Grid. For that we'll have to use XDR transforms. No, that's not very complicated, and here's how we'll do it.

1. First we're going to save the XML returned into an XML file. I've saved it as "data.xml".
2. Run XML mapper from the Tools menu, and open this XML file. Here's a mega screen shot:

｛用C#开发web services的时候，如果你这样写  oleDbDataAdapter1.Fill(ds,'tablename');｝那么你是看不到上面橙色筐中的字段的。千万不要表明数据集中表名。你这样写就可以了，oleDbDataAdapter1.Fill(ds);就能显示字段了！

3. The ZIPDATA(*) means there's multiple rows of "ZIPDATA" available. Columns availabl are Zip, City, State, County and AreaCode. Let's double-click each one of these to add them to the transformation and then click the DataPacket from XML in the Create Menu. Here's what it all looks like:

4. Save the Transformation using File | Save | Transformation, as "Ziptrans.xtr". Don't try to test the transformation yet. (There's a bug in Delphi Source code that doesn't like SOAP namespaces in certain elements so it doesn't show up any data).

5. We'll now FIX this bug. The XTR file is an XML file which you can open in any text editor. Open it, and change the first line from:

<SelectEach dest="DATAPACKETROWDATAROW" from="soap:Envelopesoap:Body....">

   [Change To]

<SelectEach dest="DATAPACKETROWDATAROW" from="Envelopesoap:Body....">

{from后面除了soap:，只要是单词后面有冒号的，该单词和冒号都要去掉，delphi才能显示数据}

6. We're nearly there. Drop a TClientDataset, a TXMLTransformProvider and a TDatasource on the form. Here's what the form looks like now:

Link the Grid, the Datasource and the ClientDataset, and set the ClientDataset's ProviderName to point to the XML Transform Provider. 7. Set the TransformRead.TransformationFile of the XMLTransformProvider to Ziptrans.XTR.

8. Now we need to set the data of the XML Transform Provider at run time. Here's some additional code in the HTTPRio's OnAfterExecute:

procedure TForm1.HTTPRIO1AfterExecute(const MethodName: String;
  SOAPResponse: TStream);
var
  XMLDoc: IXMLDocument;
begin
  SOAPResponse.Position := 0;
  Memo1.Lines.LoadFromStream(SOAPResponse);

  ClientDataset1.Active := FALSE;
  SOAPResponse.Position := 0;
  XMLDoc := NewXMLDocument;
  XMLDoc.Encoding := SUTF8; //应该是'SUTF8'并需要引用XMLIntf,XMLDoc两个单元
  SOAPResponse.Position := 0;
  XMLDoc.LoadFromStream(SOAPResponse);

  XMLTransformProvider1.TransformRead.SourceXmlDocument := XMLDoc.GetDOMDocument;
  ClientDataset1.Active := TRUE;
end;

That's it!

Amazing.

Thank you.

What's next?

This transformation is very specific to this particular service and XML schema. SO if you know what XML is going to be returned (the format) then you can use XML mapper to generate a transformation for it.

I haven't been able to write a "general" transform that can be applied to ANY .NET returned XML, but if anyone does I'd love to hear about it.

Also, why have I used the HTTPRio's OnAfterExecute, rather than manipulating the the s_schema parameter? There's another bug in Delphi that doesn't like parameters returned as XML. More revealed in this thread.

You can download all the code for this project at http://codecentral.borland.com/codecentral/ccweb.exe/listing?id=17807 or at http://www.agnisoft.com/soap/dotnetds.zip.

Deepak Shenoy(shenoy@agnisoft.com) is a Director at Agni Software, a software company in India that offers consultancy and offshore development solutions. It might be a while before his hair gets pointy so he's allowed to understand some technology.