double类型的公式换算

在进行double类型的数字计算时，如果直接用加减乘除的符号进行换算时，总是会碰到有时候差几分。总是很苦恼，尤其是对于涉及到钱的交易系统中，计算的精准性就更显得尤为重要。故放开公式计算的类，供以后参考。

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import java.math.BigDecimal;import java.text.DecimalFormat;import org.apache.commons.lang.StringUtils;public class DoubleUtils {private static final int DEF_DIV_SCALE = 10;/** * 提供精确的加法运算 7. * @param v1 被加数 8. * @param v2 加数 9. * @return 两个参数的和 *  */public static int compareWeight(double v1, double v2) {BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));b1 = b1.setScale(4, BigDecimal.ROUND_HALF_UP);b2 = b2.setScale(4, BigDecimal.ROUND_HALF_UP);return b1.compareTo(b2);}/** * 金额的比较 * @return  */public static int compareMoney(double v1, double v2) {BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));b1 = b1.setScale(2, BigDecimal.ROUND_HALF_UP);b2 = b2.setScale(2, BigDecimal.ROUND_HALF_UP);return b1.compareTo(b2);}/** * 提供精确的加法运算  * @param v1 被加数  * @param v2 加数  * @return 两个参数的和 *  */public static double add(double v1, double v2) {BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));return b1.add(b2).doubleValue();}/** * 提供精确的减法运算 * @return */public static double substract(double v1, double v2) {BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));return b1.subtract(b2).doubleValue();}/** * 提供精确的乘法运算  * @return */public static double multiply(double v1, double v2) {BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));return b1.multiply(b2).doubleValue();}/** * * 提供（相对）精确的除法运算,当发生除不尽的情况时, 精确到小数点以后10位,以后的数字四舍五入.  * @param v1 被除数   * @param v2 除数  * @return 两个参数的商. */public static double divide(double v1, double v2) {return divide(v1, v2, DEF_DIV_SCALE);}/** * 提供（相对）精确的除法运算. 当发生除不尽的情况时,由scale参数指 定精度,以后的数字四舍五入.  * @param v1 被除数  * @param v2 除数  * @param scale 表示需要精确到小数点以后几位  * @return 两个参数的商  */public static double divide(double v1, double v2, int scale) {if (scale < 0) {throw new IllegalArgumentException("The scale must be a positive integer or zero");}BigDecimal b1 = new BigDecimal(Double.toString(v1));BigDecimal b2 = new BigDecimal(Double.toString(v2));return b1.divide(b2, scale, BigDecimal.ROUND_HALF_UP).doubleValue();}/** * 提供精确的小数位四舍五入处理  * @param v 需要四舍五入的数字  * @param scale 小数点后保留几位 * @return 四舍五入后的结果  */public static double round(double v, int scale) {if (scale < 0) {throw new IllegalArgumentException("The scale must be a positive integer or zero");}BigDecimal b = new BigDecimal(Double.toString(v));BigDecimal one = new BigDecimal("1");return b.divide(one, scale, BigDecimal.ROUND_HALF_UP).doubleValue();}public static double roundMoney(double v) {BigDecimal b = new BigDecimal(Double.toString(v));BigDecimal one = new BigDecimal("1");return b.divide(one, 2, BigDecimal.ROUND_HALF_UP).doubleValue();}public static double roundWeight(double v) {BigDecimal b = new BigDecimal(Double.toString(v));BigDecimal one = new BigDecimal("1");return b.divide(one, 4, BigDecimal.ROUND_HALF_UP).doubleValue();}public static String toMoney(double amount) {DecimalFormat df = new DecimalFormat("0.00");return df.format(amount);}/** * 将以元为单位的金额转换成以分为单位的金额 *  * @param amount * @return */public static String toMinuteMoney(double amount) {if (compareMoney(amount, 0) == 0)return "0";DecimalFormat df = new DecimalFormat("0");return df.format(multiply(roundMoney(amount), 100));}/** * 将以元为单位的金额转换成以分为单位的金额 *  * @param amount * @return */public static double toYuanMoney(double amount) {if (compareMoney(amount, 0) == 0)return amount;return roundMoney(divide(amount, 100));}/** * 将以元为单位的金额转换成以分为单位的金额 *  * @param amount * @return */public static double toYuanMoney(String amount) {if (StringUtils.isBlank(amount))return 0;return roundMoney(divide(Double.parseDouble(amount), 100));}/** * 将放大了10000倍后的利率还原成原形 *  * @param rate * @return */public static double toRealRate(String rate) {if (StringUtils.isBlank(rate))return 0;return round(divide(Double.parseDouble(rate), 10000), 5);}/** * 将放大了10000倍后的利率 *  * @param rate * @return */public static String toMaxRate(double rate) {if (compareMoney(rate, 0) == 0)return "0";DecimalFormat df = new DecimalFormat("0");return df.format(multiply(roundMoney(rate), 10000));}public static void main(String[] args) {double str = DoubleUtils.toYuanMoney("1100007");System.out.println(str);}/*** * 是否为正整数 */public static boolean isPositiveInteger(double value) {long a = (long) value;if (a != value || a < 0) {return false;}return true;}/*** * 是否为正整数 */public static boolean isPositiveInteger(String value) {double d = Double.parseDouble(value);long a = (long) d;if (a != d || a < 0) {return false;}return true;}}

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