Delphi中解析Xml的控件-SimDesign NativeXml

Delphi中解析Xml的控件-SimDesign NativeXml

正在学习，感觉应用很方便。无源代码的版本还是免费的。

SimDesign.NativeXml是一个delphi和bcb的XML控件，包含一个精巧的Delphi XML执行，使你能在程序中读写XML文档。

http://www.simdesign.nl/xml.html

网上有一个利用SimDesign.NativeXml生成XML的例子。

一个更加强大易用的XML库 -- NativeXML

原来一直使用Delphi自带的TXMLDocument类来进行XML文件的读写，虽然麻烦了一点，但功能上来说还不错。只是有一个地方让我实在不舒服 - 每次创建TXMLDocument类实例的时候必须传入TComponent对象，这就意味着，如果我把对XML文件的读写封装到一个类里面，那么在创建这个自定义类的时候就必须也传入TComponent对象。

我尝试过很多方法，但是都无法避免，最后试着上网找了找，于是就找到了NativeXML这个库。

下载之后马上打开Demo看了看，cool，创建TNativeXML的时候只需要传入xml文件路径就可以，再往下看就让我开始惊喜了。它已经把大多数操作都封装好了，而且还具有把任意对象序列化的能力。

比如，你能把整个Form通过 TsdXmlObjectWriter = class(TPersistent) 类存入一个XML文件，下次再读取。这样使得远程传输对象变得很简单了。

下面就是一个使用NativeXML库的例子：

目标XML结构:

<bookshift>

<book author = "test_author">

<date>2000-01-01</date>

</book>

</bookshift>

delphi 代码:

procedure WriteTest;

var

xml : TNativeXML;

n_bs : TXMLNode;

begin

//

建立根节点

xml := TNativeXml.CreateName('bookshift');

xml.EncodingString := 'GB2312';

//

输出风格为易读

xml.XmlFormat := xfReadable;

//

建立Book节点

n_bs := xml.Root.NodeNew('book');

//

写入Book节点的属性

n_bs.WriteAttribuiteString('author','test_author');

//

建立Book节点下属date节点并写入值

n_bs.WriteString('date','2000-01-01');

xml.SaveToFile('test.xml');

end;

打开test.xml文件看看吧，和上面的格式一摸一样。很简单吧，我用这个库重写了原来的XML访问类，大约节省了40%的代码量。SimDesign.NativeXml自带的读取XML文档的例子。

注意：以下代码转贴时有误，未经测试

{ Example 3

Demo unit that shows how to import XML data into record structure.

It is a "real-life" example written for one of our customers.

It shows how to use the method "NodesByName", creating a temporary

list of node elements with the same name.

It uses NativeXml to handle the conversion.

This was the original request for the conversion:

" Data should be placed in a record with this structure:

type

FieldRecord= record

FieldId: String;

FieldReq: String;

FieldType: String;

FieldCap: String;

DependField: String;

MetaType: String;

MetaData: String;

End;

De enums and the hashtables must be stored in MetaData,

in the following manner:

Enums: enumvalue

_id1 + ',' + enum_caption1 + ";" +  enumvalue

_id2 + ',' + enum_caption2 + ";" + etc.....

HashTable: codeid1 + ',' + hashdata1 + ';'  +

codeid2 + ',' + hashdata2 + etc......

If there's no MetaData the field should remain empty. "

Author: Nils Haeck, Simdesign

http://www.simdesign.nl

More info at:

http://www.simdesign.nl/xml.html

}

unit Example3Main;

interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,

StdCtrls, NativeXml, ComCtrls;

type

// This is the record structure

FieldRecord= record

FieldId: String;

FieldReq: String;

FieldType: String;

FieldCap: String;

DependField: String;

MetaType: String;

MetaData: String;

end;

//////////////////////////////////////////////////////////////////

TForm1 = class(TForm)

mmXML: TMemo;

btnImportXML: TButton;

lbStatus: TLabel;

Label1: TLabel;

lvTable: TListView;

Label2: TLabel;

Label3: TLabel;

procedure btnImportXMLClick(Sender: TObject);

procedure lvTableData(Sender: TObject; Item: TListItem);

private

public

Fields: array of FieldRecord; // This is a dynamic array of records

procedure LoadFieldFromNode(var AField: FieldRecord; ANode: TXmlNode);

end;

var

Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.btnImportXMLClick(Sender: TObject);

// Read XML from TMemo and convert into record structure

var

i: integer;

ADoc: TNativeXml;

ANode: TXmlNode;

AList: TList;

begin

ADoc := TNativeXml.Create;

try

// Read from memo

ADoc.ReadFromString(mmXML.Text);

// A temporary list to hold references to the record elements

AList := TList.Create;

try

ANode := ADoc.Root.NodeByName('fields');

if not assigned(ANode) then exit;

// List of nodes that are named "field"

ANode.NodesByName('field', AList);

// Set dynamic array length

SetLength(Fields, AList.Count);

// Import each element

for i := 0 to AList.Count - 1 do

LoadFieldFromNode(Fields[I], AList[I]);

// Show table

lvTable.Items.Count := AList.Count;

lvTable.Invalidate;

// Status

lbStatus.Caption := Format('Imported %d records', [AList.Count]);

finally

AList.Free;

end;

finally

ADoc.Free;

end;

end;

procedure TForm1.LoadFieldFromNode(var AField: FieldRecord;

ANode: TXmlNode);

// Load one field from the XML element ANode

var

i: integer;

AMeta: TXmlNode;

AEnum: TXmlNode;

AList: TList;

begin

with AField, ANode do begin

// Initialize record

FillChar(AField, SizeOf(AField), 0);

// The flat data

FieldId      := AttributeByName['id'];

FieldReq     := AttributeByName['required'];

FieldType    := AttributeByName['type'];

FieldCap     := ReadString('caption');

DependField  := AttributeByName['dependsfield'];

// Meta data

AMeta := NodeByName('metadata');

if assigned(AMeta) then

with AMeta do

begin

MetaType := AttributeByName['type'];

///////////////////////////////////////////////////////////////

// List that holds enumeration

AList := TList.Create;

try

// "enum" metadata

if MetaType = 'enum' then

begin

AEnum := NodeByName('enumeration');

if assigned(AEnum) then

AEnum.NodesByName('enumvalue', AList);

// all enumeration values

for i := 0 to AList.Count - 1 do

with TXmlNode(AList[I) do

MetaData := MetaData +

AttributeByName['id'] + ',' + ReadString('caption') + ';';

end;

// "hashtable" metadata

if MetaType = 'hashtable' then

begin

AEnum := NodeByName('hashtable');

if assigned(AEnum) then

AEnum.NodesByName('code', AList);

// all enumeration values

for i := 0 to AList.Count - 1 do with TXmlNode(AList[I]) do

MetaData := MetaData +

AttributeByName['id'] + ',' + valueAsString + ';';

end;

finally

AList.Free;

end;

end;

end;

end;

procedure TForm1.lvTableData(Sender: TObject; Item: TListItem);

// Add data to each item in the listview. We use the listview with OwnerData

begin

if (Item.Index >= 0) and (Item.Index < Length(Fields)) then

begin

with Fields[Item.Index] do

begin

Item.Caption := FieldID;

Item.SubItems.Add(FieldReq);

Item.SubItems.Add(FieldType);

Item.SubItems.Add(FieldCap);

Item.SubItems.Add(DependField);

Item.SubItems.Add(MetaType);

Item.SubItems.Add(MetaData);

end;

end;

end;

end.