//定义

Dictionary openWith =newDictionary();

//添加元素

openWith.Add("txt","notepad.exe");

    openWith.Add("bmp","paint.exe");

    openWith.Add("dib","paint.exe");

    openWith.Add("rtf","wordpad.exe");

具体用法参照：https://www.cnblogs.com/herizai/p/6961332.html