在非Windows机器上使用php处理所有版本的MS Excel电子表格的最佳方法是什么

I am importing data from MS Excel spreadsheets into a php/mySQL application. Several different parties are supplying the spreadsheets and they are in formats ranging from Excel 4.0 to Excel 2007. The trouble is finding a technique to read ALL versions.I am importing data from MS Excel spreadsheets