求百分比

import java.math.BigDecimal;

String discount = null ;
String discount = null ;
double discountDouble = 0 ;

BigDecimal b1 = new BigDecimal(Integer.toString(referencePrice));
BigDecimal b3 = new BigDecimal(Integer.toString(unitPrice));

discountDouble = b3.divide(b1, 2, BigDecimal.ROUND_HALF_UP)
.doubleValue() * 100.0;

discount = String.valueOf(discountDouble) + "%";