如何读取和写入XML文档节点值？

Question

我想读取XML文件的一些节点，并在一些自定义输入字段中显示它们的值。用户可以根据需要更改这些值，并通过单击Next按钮将这些值保存回XML。

如何在InnoSetup脚本中做到这一点？

Answer 1

使用CreateOleObject函数实例化标准的MSXML2.DOMDocument COM对象。下面的脚本显示了如何加载和保存文本值用于从下面贴（脚本本身通过从MSDN实施例的启发）的XML文件中的单个节点：

[Setup] 
AppName=My Program 
AppVersion=1.5 
DefaultDirName={pf}\My Program 
DefaultGroupName=My Program 
UninstallDisplayIcon={app}\MyProg.exe 
Compression=lzma2 
SolidCompression=yes 
OutputDir=userdocs:Inno Setup Examples Output 

[Files] 
Source: "MyProg.exe"; DestDir: "{app}" 
Source: "MyProg.chm"; DestDir: "{app}" 

[Icons] 
Name: "{group}\My Program"; Filename: "{app}\MyProg.exe" 

[Code] 
var 
    CustomEdit: TEdit; 
    CustomPageID: Integer; 

function LoadValueFromXML(const AFileName, APath: string): string; 
var 
    XMLNode: Variant; 
    XMLDocument: Variant; 
begin 
    Result := ''; 
    XMLDocument := CreateOleObject('Msxml2.DOMDocument.6.0'); 
    try 
    XMLDocument.async := False; 
    XMLDocument.load(AFileName); 
    if (XMLDocument.parseError.errorCode <> 0) then 
     MsgBox('The XML file could not be parsed. ' + 
     XMLDocument.parseError.reason, mbError, MB_OK) 
    else 
    begin 
     XMLDocument.setProperty('SelectionLanguage', 'XPath'); 
     XMLNode := XMLDocument.selectSingleNode(APath); 
     Result := XMLNode.text; 
    end; 
    except 
    MsgBox('An error occured!' + #13#10 + GetExceptionMessage, mbError, MB_OK); 
    end; 
end; 

procedure SaveValueToXML(const AFileName, APath, AValue: string); 
var 
    XMLNode: Variant; 
    XMLDocument: Variant; 
begin 
    XMLDocument := CreateOleObject('Msxml2.DOMDocument.6.0'); 
    try 
    XMLDocument.async := False; 
    XMLDocument.load(AFileName); 
    if (XMLDocument.parseError.errorCode <> 0) then 
     MsgBox('The XML file could not be parsed. ' + 
     XMLDocument.parseError.reason, mbError, MB_OK) 
    else 
    begin 
     XMLDocument.setProperty('SelectionLanguage', 'XPath'); 
     XMLNode := XMLDocument.selectSingleNode(APath); 
     XMLNode.text := AValue; 
     XMLDocument.save(AFileName); 
    end; 
    except 
    MsgBox('An error occured!' + #13#10 + GetExceptionMessage, mbError, MB_OK); 
    end; 
end; 

procedure InitializeWizard; 
var 
    CustomPage: TWizardPage; 
begin 
    CustomPage := CreateCustomPage(wpWelcome, 'Custom Page', 
    'Enter the new value that will be saved into the XML file'); 
    CustomPageID := CustomPage.ID; 
    CustomEdit := TEdit.Create(WizardForm); 
    CustomEdit.Parent := CustomPage.Surface; 
end; 

procedure CurPageChanged(CurPageID: Integer); 
begin 
    if CurPageID = CustomPageID then 
    CustomEdit.Text := LoadValueFromXML('C:\Setup.xml', '//Setup/FirstNode'); 
end; 

function NextButtonClick(CurPageID: Integer): Boolean; 
begin 
    Result := True; 
    if CurPageID = CustomPageID then 
    SaveValueToXML('C:\Setup.xml', '//Setup/FirstNode', CustomEdit.Text); 
end; 

下面是在所使用的XML文件脚本：

<?xml version="1.0" encoding="UTF-8"?> 
<Setup> 
    <FirstNode>First node value!</FirstNode> 
    <SecondNode>Second node value!</SecondNode> 
</Setup>