安装前可以先卸载之前的版本：
如果您无法进行完全卸载，则必须实施部分卸载。
理想的做法是对卸载程序日志 (unins000.dat) 进行逆向工程，仅将安装提取到 lib 子文件夹并处理（撤消）它们。但由于这是一个未记录的二进制文件，因此可能很难做到。
如果您在 [Files] 部分中维护要安装的文件的明确列表，例如
[Files]
Source: "lib\dependency-A-1.2.3.jar"; Dest: "{app}\lib"
Source: "lib\dependency-B-2.3.4.jar"; Dest: "{app}\lib"
然后每当依赖项发生变化时，将以前的版本移动到 [InstallDelete] 部分：
[Files]
Source: "lib\dependency-A-1.3.0.jar"; Dest: "{app}"
Source: "lib\dependency-B-2.3.4.jar"; Dest: "{app}"
[InstallDelete]
{app}\lib\dependency-A-1.2.3.jar
如果您使用通配符安装依赖项，
[Files]
Source: "lib\*.jar"; Dest: "{app}\lib"
而且您无法对卸载程序日志进行反向工程，您必须通过自己的方式复制其功能。
您可以使用preprocessor 生成包含已安装依赖项的文件。将该文件安装到{app} 文件夹并在安装前处理该文件。
[Files]
Source: "MyApp.jar"; DestDir: "{app}"
Source: "lib\*.jar"; DestDir: "{app}\lib"
#define ProcessFile(Source, FindResult, FindHandle) \
Local[0] = FindGetFileName(FindHandle), \
Local[1] = Source + "\\" + Local[0], \
Local[2] = FindNext(FindHandle), \
"'" + Local[0] + "'#13#10" + \
(Local[2] ? ProcessFile(Source, Local[2], FindHandle) : "")
#define ProcessFolder(Source) \
Local[0] = FindFirst(Source + "\\*.jar", faAnyFile), \
ProcessFile(Source, Local[0], Local[0])
#define DepedenciesToInstall ProcessFolder("lib")
#define DependenciesLog "{app}\dependencies.log"
[UninstallDelete]
Type: files; Name: "{#DependenciesLog}"
[Code]
procedure CurStepChanged(CurStep: TSetupStep);
var
AppPath, DependenciesLogPath: string;
Dependencies: TArrayOfString;
Count, I: Integer;
begin
DependenciesLogPath := ExpandConstant('{#DependenciesLog}');
if CurStep = ssInstall then
begin
// If dependencies log already exists,
// remove the previously installed dependencies
if LoadStringsFromFile(DependenciesLogPath, Dependencies) then
begin
Count := GetArrayLength(Dependencies);
Log(Format('Loaded %d dependencies, deleting...', [Count]));
for I := 0 to Count - 1 do
DeleteFile(ExpandConstant('{app}\lib\' + Dependencies[I]));
end;
end
else
if CurStep = ssPostInstall then
begin
// Now that the app folder already exists,
// save dependencies log (to be processed by future upgrade)
if SaveStringToFile(DependenciesLogPath, {#DepedenciesToInstall}, False) then
begin
Log('Created dependencies log');
end
else
begin
Log('Failed to create dependencies log');
end;
end;
end;
另一种方法是删除安装文件夹中所有最新安装程序未安装的文件。
最简单的解决方法是在安装前删除安装文件夹中的所有文件。
您可以为此使用[InstallDelete] section。但是如果您在安装文件夹中有一些带有配置的文件夹/文件，则不允许您排除它们。
您可以改为编写 Pascal 脚本。见Inno Setup - Delete whole application folder except for data subdirectory。您可以从我对CurStepChanged(ssInstall) 事件函数的那个问题的回答中调用DelTreeExceptSavesDir 函数：
procedure CurStepChanged(CurStep: TSetupStep);
begin
if CurStep = ssInstall then
begin
DelTreeExceptSavesDir(WizardDirValue);
end;
end;
如果您真的只想删除过时的文件，以避免删除和重新创建现有文件，您可以使用预处理器生成要为 Pascal 脚本安装的文件列表，并使用它来仅删除真正过时的文件。
#pragma parseroption -p-
#define FileEntry(DestDir) \
" FilesNotToBeDeleted.Add('" + LowerCase(DestDir) + "');\n"
#define ProcessFile(Source, Dest, FindResult, FindHandle) \
FindResult \
? \
Local[0] = FindGetFileName(FindHandle), \
Local[1] = Source + "\\" + Local[0], \
Local[2] = Dest + "\\" + Local[0], \
(Local[0] != "." && Local[0] != ".." \
? FileEntry(Local[2]) + \
(DirExists(Local[1]) ? ProcessFolder(Local[1], Local[2]) : "") \
: "") + \
ProcessFile(Source, Dest, FindNext(FindHandle), FindHandle) \
: \
""
#define ProcessFolder(Source, Dest) \
Local[0] = FindFirst(Source + "\\*", faAnyFile), \
ProcessFile(Source, Dest, Local[0], Local[0])
#pragma parseroption -p+
[Code]
var
FilesNotToBeDeleted: TStringList;
function InitializeSetup(): Boolean;
begin
FilesNotToBeDeleted := TStringList.Create;
FilesNotToBeDeleted.Add('\data');
{#Trim(ProcessFolder('build\exe.win-amd64-3.6', ''))}
FilesNotToBeDeleted.Sorted := True;
Result := True;
end;
procedure DeleteObsoleteFiles(Path: string; RelativePath: string);
var
FindRec: TFindRec;
FilePath: string;
FileRelativePath: string;
begin
if FindFirst(Path + '\*', FindRec) then
begin
try
repeat
if (FindRec.Name <> '.') and (FindRec.Name <> '..') then
begin
FilePath := Path + '\' + FindRec.Name;
FileRelativePath := RelativePath + '\' + FindRec.Name;
if FindRec.Attributes and FILE_ATTRIBUTE_DIRECTORY <> 0 then
begin
DeleteObsoleteFiles(FilePath, FileRelativePath);
end;
if FilesNotToBeDeleted.IndexOf(Lowercase(FileRelativePath)) < 0 then
begin
if FindRec.Attributes and FILE_ATTRIBUTE_DIRECTORY <> 0 then
begin
if RemoveDir(FilePath) then
begin
Log(Format('Deleted obsolete directory %s', [FilePath]));
end
else
begin
Log(Format('Failed to delete obsolete directory %s', [FilePath]));
end;
end
else
begin
if DeleteFile(FilePath) then
begin
Log(Format('Deleted obsolete file %s', [FilePath]));
end
else
begin
Log(Format('Failed to delete obsolete file %s', [FilePath]));
end;
end;
end;
end;
until not FindNext(FindRec);
finally
FindClose(FindRec);
end;
end
else
begin
Log(Format('Failed to list %s', [Path]));
end;
end;
procedure CurStepChanged(CurStep: TSetupStep);
begin
if CurStep = ssInstall then
begin
Log('Looking for obsolete files...');
DeleteObsoleteFiles(WizardDirValue, '');
end;
end;