如何仅在尚未安装.NET Framework的情况下安装它？ [英] How do I install .NET Framework only when it's not already installed?

问题描述

有没有一种方法可以检查是否已安装.NET Framework 4并仅在不在系统中时才安装它？

Is there a way to check if the .NET Framework 4 has been installed and install it only when it's not in the system?

我知道，我该怎么办？通过检查以下注册表项来确定是否安装了.NET Framework 4？

I know, how do I determine, if the .NET Framework 4 is installed by checking the following registry key?

hasDotnet4 :=
  RegKeyExists(HKEY_LOCAL_MACHINE, 'SOFTWARE\Microsoft\.NETFramework\policy\v4.0');

如何基于上述检查有条件地运行.NET Framework 4安装？

How do I conditionally run the .NET Framework 4 installation based on the above check?

推荐答案

最简单的方法是使用 Check 参数，它允许您控制是否来自 [文件] 部分，或者如果 [运行] 部分将被执行。以下脚本代码显示了其在.NET Framework 4的条件安装中的用法：

The easiest you can do, is to use the Check parameter, which allows you to control if a certain file from the [Files] section will be extracted, or if a certain program from the [Run] section will be executed. The following script code shows its usage for the conditional installation of the .NET Framework 4:

[Files]
Source: "dotNetFx40_Full_setup.exe"; DestDir: {tmp}; \
  Flags: deleteafterinstall; Check: FrameworkIsNotInstalled

[Run]
Filename: "{tmp}\dotNetFx40_Full_setup.exe"; Check: FrameworkIsNotInstalled

[Code]

function FrameworkIsNotInstalled: Boolean;
begin
  Result :=
    not RegKeyExists(
      HKEY_LOCAL_MACHINE, 'SOFTWARE\Microsoft\.NETFramework\policy\v4.0');
end;

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