Delphi XML遍历
我是Delphi的新手。
我想在每个主题下找到所有作者。
这是我的XML
<?xml version="1.0"?>
<catalog>
<subject id="computer">
<book id="bk101">
<author>Gambardella, Matthew</author>
<title>XML Developer's Guide</title>
<genre>Computer</genre>
<price>44.95</price>
<publish_date>2000-10-01</publish_date>
<description>An in-depth look at creating applications
with XML.</description>
</book>
<book id="bk112">
<author>Galos, Mike</author>
<title>Visual Studio 7: A Comprehensive Guide</title>
<genre>Computer</genre>
<price>49.95</price>
<publish_date>2001-04-16</publish_date>
<description>Microsoft Visual Studio 7 is explored in depth,
looking at how Visual Basic, Visual C++, C#, and ASP+ are
integrated into a comprehensive development
environment.</description>
</book>
</subject>
<subject id="literature">
<book id="bk102">
<author>Ralls, Kim</author>
<title>Midnight Rain</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2000-12-16</publish_date>
<description>A former architect battles corporate zombies,
an evil sorceress, and her own childhood to become queen
of the world.</description>
</book>
<book id="bk103">
<author>Corets, Eva</author>
<title>Maeve Ascendant</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2000-11-17</publish_date>
<description>After the collapse of a nanotechnology
society in England, the young survivors lay the
foundation for a new society.</description>
</book>
<book id="bk104">
<author>Corets, Eva</author>
<title>Oberon's Legacy</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2001-03-10</publish_date>
<description>In post-apocalypse England, the mysterious
agent known only as Oberon helps to create a new life
for the inhabitants of London. Sequel to Maeve
Ascendant.</description>
</book>
<book id="bk105">
<author>Corets, Eva</author>
<title>The Sundered Grail</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2001-09-10</publish_date>
<description>The two daughters of Maeve, half-sisters,
battle one another for control of England. Sequel to
Oberon's Legacy.</description>
</book>
<book id="bk106">
<author>Randall, Cynthia</author>
<title>Lover Birds</title>
<genre>Romance</genre>
<price>4.95</price>
<publish_date>2000-09-02</publish_date>
<description>When Carla meets Paul at an ornithology
conference, tempers fly as feathers get ruffled.</description>
</book>
<book id="bk107">
<author>Thurman, Paula</author>
<title>Splish Splash</title>
<genre>Romance</genre>
<price>4.95</price>
<publish_date>2000-11-02</publish_date>
<description>A deep sea diver finds true love twenty
thousand leagues beneath the sea.</description>
</book>
<book id="bk108">
<author>Knorr, Stefan</author>
<title>Creepy Crawlies</title>
<genre>Horror</genre>
<price>4.95</price>
<publish_date>2000-12-06</publish_date>
<description>An anthology of horror stories about roaches,
centipedes, scorpions and other insects.</description>
</book>
<book id="bk109">
<author>Kress, Peter</author>
<title>Paradox Lost</title>
<genre>Science Fiction</genre>
<price>6.95</price>
<publish_date>2000-11-02</publish_date>
<description>After an inadvertant trip through a Heisenberg
Uncertainty Device, James Salway discovers the problems
of being quantum.</description>
</book>
<book id="bk110">
<author>O'Brien, Tim</author>
<title>Microsoft .NET: The Programming Bible</title>
<genre>Computer</genre>
<price>36.95</price>
<publish_date>2000-12-09</publish_date>
<description>Microsoft's .NET initiative is explored in
detail in this deep programmer's reference.</description>
</book>
<book id="bk111">
<author>O'Brien, Tim</author>
<title>MSXML3: A Comprehensive Guide</title>
<genre>Computer</genre>
<price>36.95</price>
<publish_date>2000-12-01</publish_date>
<description>The Microsoft MSXML3 parser is covered in
detail, with attention to XML DOM interfaces, XSLT processing,
SAX and more.</description>
</book>
</subject>
</catalog>
你可以使用XPath来选择所有的作者，使用像这样的表达式//catalog/subject/book/author ，从delphi你有很多选项来管理一个XML文件，但在这种情况下最简单的就是使用Microsoft XML DOM implementation
检查此示例应用程序
{$APPTYPE CONSOLE}
uses
ActiveX,
Variants,
ComObj,
SysUtils;
procedure ReadXMLFile(const FileName:TFileName);
const
Msxml2_DOMDocument='Msxml2.DOMDocument.6.0';
var
XmlDoc : OleVariant;
Nodes : OleVariant;
lNodes : Integer;
i : Integer;
begin
//create an instance to the XML DOM
XmlDoc := CreateOleObject(Msxml2_DOMDocument);
try
XmlDoc.Async := False;
//load the file
XmlDoc.Load(FileName);
//set the xpath mode
XmlDoc.SetProperty('SelectionLanguage','XPath');
//check for errors in the xml file
if (XmlDoc.parseError.errorCode <> 0) then
raise Exception.CreateFmt('Error in Xml Data %s',[XmlDoc.parseError]);
//select the nodes with match with the expression
Nodes := XmlDoc.selectNodes('//catalog/subject/book/author');
//get the number of nodes selected
lNodes:= Nodes.Length;
Writeln(Format('%d Authors found',[lNodes]));
//traverse the nodes
for i:=0 to Nodes.Length - 1 do
Writeln(Format('Author Name %s',[Nodes.Item(i).Text]));
finally
XmlDoc :=Unassigned;
end;
end;
begin
try
CoInitialize(nil);
try
ReadXMLFile(ExtractFilePath(ParamStr(0))+'test.xml');
finally
CoUninitialize;
end;
except
on E:Exception do
Writeln(E.Classname, ':', E.Message);
end;
Writeln('Press Enter to exit');
Readln;
end.
最后应用程序将返回此
12 Authors found
Author Name Gambardella, Matthew
Author Name Galos, Mike
Author Name Ralls, Kim
Author Name Corets, Eva
Author Name Corets, Eva
Author Name Corets, Eva
Author Name Randall, Cynthia
Author Name Thurman, Paula
Author Name Knorr, Stefan
Author Name Kress, Peter
Author Name O'Brien, Tim
Author Name O'Brien, Tim
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