将BigDecimal转成字符串为科学计数法的踩坑记录

目录BigDecimal转字符串为科学计数法踩坑场景解决案例演示BigDecimal变科学计数法

BigDecimal转字符串为科学计数法踩坑

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：

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

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

costBudgetEntity.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

解决

查frEupH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。

/**

* 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 prhttp://ocessed 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<0) { // No decimal point

if(signum()==0) {

return "0";

}

int tailingZeros = checkScaleNonZero((-(long)scale));

StringBuilder buf;

if(intCompact!=INFLATED) {

buf = new StringBuilder(20+tailingZeros);

buf.append(intCompact);

} elsefrEupH {

String str = intVal.toString();

buf = new StringBuilder(str.length()+tailingZeros);

buf.append(str);

}

for (int i = 0; i < tailingZeros; i++)

buf.append('0');

return buf.toString();

}

String str ;

if(intCompact!=INFLATED) {

str = Long.toString(Math.abs(intCompact));

} else {

str = intVal.abs().toString();

}

return getValueString(signum(), str, scale);

}

此时，我们在debug查看：

costBudgetEntity.getInitTotalAmount().toPlainString() //金额为12000000输出的结果为12000000字符串

案例演示

BigDecimal变科学计数法

阿里OTS存储BigDecimal

当BigDecimal数据大于9,999,999时

后就变成科学计数法了。

如10,000,000 就变为1.0E7

接收端应该注意

也需要用BigDecimal，要是使用Integer接收，就可能出现异常

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