BigDecimal类型比较大小
if (a.compareTo(b) == -1) {
System.out.println("a小于b");
}
if (a.compareTo(b) == 0) {
System.out.println("a等于b");
}
if (a.compareTo(b) == 1) {
System.out.println("a大于b");
}
if (a.compareTo(b) > -1) {
System.out.println("a大于等于b");
}
if (a.compareTo(b) < 1) {
System.out.println("a小于等于b");
}
