Sharcoux Sharcoux - 1 month ago 27
Java Question

Inno Setup, detect Java version

When installing my Java app with Inno Setup, I would like the installer to check if Java 7 or above is present, and install it if needed. But apparently, my current code fails to detect Java 8 on the computer of some of my clients. I couldn't reproduce the bug, though. Do you see something that I could be missing? Maybe this code doesn't work with recent Windows?

Basically, I just check the registry for Java >= 1.7.

[Code]

function InitializeSetup(): Boolean;
var
ErrorCode: Integer;
JavaInstalled : Boolean;
ResultMsg : Boolean;
Versions: TArrayOfString;
I: Integer;
regRoot: Integer;
begin
{ Check which view of registry should be taken: }
regRoot := HKLM
begin
if IsWin64 then
begin
regRoot := HKLM64
end;
end;
if (RegGetSubkeyNames(regRoot, 'SOFTWARE\JavaSoft\Java Runtime Environment', Versions)) or (RegGetSubkeyNames(regRoot, 'SOFTWARE\JavaSoft\Java Development Kit', Versions)) then
begin
for I := 0 to GetArrayLength(Versions)-1 do
if JavaInstalled = true then
begin
//do nothing
end else
begin
if ( Versions[I][2]='.' ) and ( ( StrToInt(Versions[I][1]) > 1 ) or ( ( StrToInt(Versions[I][1]) = 1 ) and ( StrToInt(Versions[I][3]) >= 7 ) ) ) then
begin
JavaInstalled := true;
end else
begin
JavaInstalled := false;
end;
end;
end else
begin
JavaInstalled := false;
end;

if JavaInstalled then
begin
Result := true;
end else
begin
ResultMsg := MsgBox(ExpandConstant('{cm:JavaRequired}'), mbConfirmation, MB_YESNO) = idYes;
if ResultMsg = false then
begin
Result := false;
end else
begin
Result := true;
ShellExec('open', 'http://www.java.com/getjava/', '','',SW_SHOWNORMAL,ewNoWait,ErrorCode);
end;
end;
end;


** Edit **: This is the final result based on Martin's answer.

[Code]
function CutJavaVersionPart(var V: string): Integer;
var
S: string;
P: Integer;
begin
if Length(V) = 0 then
begin
Result := 0;
end
else
begin
P := Pos('.', V);
if P = 0 then P := Pos('_', V);

if P > 0 then
begin
S := Copy(V, 1, P - 1);
Delete(V, 1, P);
end
else
begin
S := V;
V := '';
end;
Result := StrToIntDef(S, 0);
end;
end;

function MaxJavaVersion(V1, V2: string): string;
var
Part1, Part2: Integer;
Buf1, Buf2: string;
begin
Buf1 := V1;
Buf2 := V2;
Result := '';
while (Result = '') and
((Buf1 <> '') or (Buf2 <> '')) do
begin
Part1 := CutJavaVersionPart(Buf1);
Part2 := CutJavaVersionPart(Buf2);
if Part1 > Part2 then Result := V1
else
if Part2 > Part1 then Result := V2;
end;
end;

function HasJava1Dot7OrNewer: Boolean;
begin
Result := (MaxJavaVersion('1.6.9', GetJavaVersion) <> '1.6.9');
end;

function GetJavaVersion: string;
var
TempFile: string;
ResultCode: Integer;
S: AnsiString;
P: Integer;
begin
TempFile := ExpandConstant('{tmp}\javaversion.txt');
if (not ExecAsOriginalUser(
ExpandConstant('{cmd}'), '/c java -version 2> "' + TempFile + '"', '',
SW_HIDE, ewWaitUntilTerminated, ResultCode)) or
(ResultCode <> 0) then
begin
Log('Failed to execute java -version');
end
else
if not LoadStringFromFile(TempFile, S) then
begin
Log(Format('Error reading file %s', [TempFile]));
end
else
if Copy(S, 1, 14) <> 'java version "' then
begin
Log('Output of the java -version not as expected');
end
else
begin
Delete(S, 1, 14);
P := Pos('"', S);
if P = 0 then
begin
Log('Output of the java -version not as expected');
end
else
begin
SetLength(S, P - 1);
Result := S;
end;
end;

DeleteFile(TempFile);
end;

function InitializeSetup(): Boolean;
var
ErrorCode: Integer;
begin
Result := HasJava1Dot7OrNewer;
if not Result then
begin
Result := MsgBox(ExpandConstant('{cm:JavaRequired}'), mbConfirmation, MB_YESNO) = idYes;
if Result then
begin
ShellExec(
'open', 'https://www.java.com/getjava/', '', '', SW_SHOWNORMAL, ewNoWait, ErrorCode);
end;
end;
end;

Answer

I do not have the JavaSoft key in HKLM\Software. I have it in HKLM\SOFTWARE\WOW6432Node. What is actually the HKLM\SOFTWARE in Inno Setup (being 32-bit application).

So it looks like you just need to remove the if IsWin64 then regRoot := HKLM64 block to make it working. Or try both options.

function CutJavaVersionPart(var V: string): Integer;
var
  S: string;
  P: Integer;
begin
  if Length(V) = 0 then
  begin
    Result := 0;
  end
    else
  begin
    P := Pos('.', V);
    if P = 0 then P := Pos('_', V);

    if P > 0 then
    begin
      S := Copy(V, 1, P - 1);
      Delete(V, 1, P);
    end
      else
    begin
      S := V;
      V := '';
    end;
    Result := StrToIntDef(S, 0);
  end;
end;

function MaxJavaVersion(V1, V2: string): string;
var
  Part1, Part2: Integer;
  Buf1, Buf2: string;
begin
  Buf1 := V1;
  Buf2 := V2;
  Result := '';
  while (Result = '') and
        ((Buf1 <> '') or (Buf2 <> '')) do
  begin
    Part1 := CutJavaVersionPart(Buf1);
    Part2 := CutJavaVersionPart(Buf2);
    if Part1 > Part2 then Result := V1
      else
    if Part2 > Part1 then Result := V2;
  end;
end;

function GetJavaVersionFromSubKey(RootKey: Integer; SubKeyName: string): string;
var
  Versions: TArrayOfString;
  I: Integer;
begin
  if RegGetSubkeyNames(RootKey, SubKeyName, Versions) then
  begin
    for I := 0 to GetArrayLength(Versions) - 1 do
    begin
      Result := MaxJavaVersion(Result, Versions[I]);
    end;
  end;
end;

function GetJavaVersionFromRootKey(RootKey: Integer): string;
begin
  Result := 
    MaxJavaVersion(
      GetJavaVersionFromSubKey(RootKey, 'SOFTWARE\JavaSoft\Java Runtime Environment'),
      GetJavaVersionFromSubKey(RootKey, 'SOFTWARE\JavaSoft\Java Development Kit'));
end;

function GetJavaVersion: string;
begin
  Result := GetJavaVersionFromRootKey(HKLM);
  if IsWin64 then
  begin
    Result := MaxJavaVersion(Result, GetJavaVersionFromRootKey(HKLM64));
  end;
end;

For your specific needs, you can check, if Java 1.7 or newer is installed like this:

function HasJava1Dot7OrNewer: Boolean;
begin
  Result := (MaxJavaVersion('1.6.9', GetJavaVersion) <> '1.6.9');
end;

Or did you consider running java -version instead?

function GetJavaVersion2: string;
var
  TempFile: string;
  ResultCode: Integer;
  S: AnsiString;
  P: Integer;
begin
  TempFile := ExpandConstant('{tmp}\javaversion.txt');
  if (not ExecAsOriginalUser(
            ExpandConstant('{cmd}'), '/c java -version 2> "' + TempFile + '"', '',
            SW_HIDE, ewWaitUntilTerminated, ResultCode)) or
     (ResultCode <> 0) then
  begin
    Log('Failed to execute java -version');
  end
    else
  if not LoadStringFromFile(TempFile, S) then
  begin
    Log(Format('Error reading file %s', [TempFile]));
  end
    else
  if Copy(S, 1, 14) <> 'java version "' then
  begin
    Log('Output of the java -version not as expected');
  end
    else
  begin
    Delete(S, 1, 14);
    P := Pos('"', S);
    if P = 0 then
    begin
      Log('Output of the java -version not as expected');
    end
      else
    begin
      SetLength(S, P - 1);
      Result := S;
    end;
  end;

  DeleteFile(TempFile);
end;

A bit more efficient implementation of the InitializeSetup:

function InitializeSetup(): Boolean;
var
  ErrorCode: Integer;
begin
  Result := HasJava1Dot7OrNewer;
  if not Result then
  begin
    Result := MsgBox(ExpandConstant('{cm:JavaRequired}'), mbConfirmation, MB_YESNO) = idYes;
    if Result then
    begin
      ShellExec(
        'open', 'https://www.java.com/getjava/', '', '', SW_SHOWNORMAL, ewNoWait, ErrorCode);
    end;
  end;
end;