防止在较新版本上安装较旧版本

Question

我想设置某些版本验证以防止最终用户在较新版本上安装旧版本。防爆。防止安装版本3时安装版本1。做这个的最好方式是什么？

Answer 1

您可以将“运行脚本”操作添加到安装程序的“启动”节点，以验证已安装的版本。

下面的代码片段演示了如何验证对较新版本，如果他们是简单的整数：

// The value returned by context.getInstallationDirectory() will be the last 
// installation directory if the user has already installed the application 
ApplicationRegistry.ApplicationInfo applicationInfo = 
    ApplicationRegistry.getApplicationInfoByDir(context.getInstallationDirectory()); 

if (applicationInfo == null) { 
    // The application has never been installed before 
    return true; 
} 

if (Integer.parseInt(applicationInfo.getVersion()) > 
    Integer.parseInt(context.getVersion())) { 
    Util.showErrorMessage("A more recent version has already been" + 
    " installed in this directory"); 
    // By returning "false", the action will fail and the installer will quit. 
    // Note that you have to set the "Failure strategy" property of your 
// "Run script" action to "Quit on error", otherwise the installer will continue. 
    return false; 
} else { 
    return true; 
}