BigDecimal转成字符串为科学计数法踩坑

一、场景

    在开发工程中，在金额方面都会定义bigdecimal类型，当然有时候也需要将金额转成字符串。我们可能会很自然的写成 金额.toString()方法如：

amount.getInitTotalAmount().toString()//获取初始预算金额的字符串

String amountInfo="到账"+amount+"元";

当然当金额过小时，转成字符串，是没有任何问题的，但当金额数值较大时，转成的字符串时科学计数法格式，这往往不是我们想要的格式。

因此

amount.getInitTotalAmount().toString()//金额为12000000输出的结果为1.2E+7这种的字符串
然后根据这种字符串，无法做一些想要的业务处理

二、解决

1.查看BigDecimal的API后，得知有个toPlainString()方法， 此方法的返回类型为String ，它返回此BigDecimal对象的字符串表示形式，不需要任何指数。

2.BigDecimal保留2位小数转成数字String amountInfo="到账"+amount.setScale(2,BigDecimal.ROUND_HALF_UP)+"元";

/**
* Returns a string representation of this {@code BigDecimal}
* without an exponent field.  For values with a positive scale,
* the number of digits to the right of the decimal point is used
* to indicate scale.  For values with a zero or negative scale,
* the resulting string is generated as if the value were
* converted to a numerically equal value with zero scale and as
* if all the trailing zeros of the zero scale value were present
* in the result.
*
* The entire string is prefixed by a minus sign character '-'
* ('\u002D') if the unscaled value is less than
* zero. No sign character is prefixed if the unscaled value is
* zero or positive.
*
* Note that if the result of this method is passed to the
* {@linkplain #BigDecimal(String) string constructor}, only the
* numerical value of this {@code BigDecimal} will necessarily be
* recovered; the representation of the new {@code BigDecimal}
* may have a different scale.  In particular, if this
* {@code BigDecimal} has a negative scale, the string resulting
* from this method will have a scale of zero when processed by
* the string constructor.
*
* (This method behaves analogously to the {@code toString}
* method in 1.4 and earlier releases.)
*
* @return a string representation of this {@code BigDecimal}
* without an exponent field.
* @since 1.5
* @see #toString()
* @see #toEngineeringString()
*/
public String toPlainString() {
    if(scale==0) {
        if(intCompact!=INFLATED) {
            return Long.toString(intCompact);
        } else {
            return intVal.toString();
        }
    }
    if(this.scale