String value = "";
double numValue = Double.valueOf(value);
//保留6位小数，并四舍五入
BigDecimal decimal = 
new BigDecimal(String.valueOf(value)).setScale(6, BigDecimal.ROUND_HALF_UP);

//去除小数点后最后的0
value = decimal.stripTrailingZeros().toPlainString();
System.out.println(cellValue);