I apologize, but there is no such class as "BigDecimalParser" in the Apache Commons IO library. It seems that you might be confusing it with other class or package. Apache Commons IO focuses on providing utility classes for file and I/O operations, and it doesn't have a specific class for parsing BigDecimal values.

Java provides a class java.math.BigDecimal for working with large decimal numbers. To parse a string into a BigDecimal, you can use the BigDecimal(String) constructor. Here is an example:

import java.math.BigDecimal;

public class BigDecimalParserExample {
    public static void main(String[] args) {
        String input = "123.456";
        BigDecimal bigDecimal = new BigDecimal(input);
        System.out.println(bigDecimal);
    }
}

This will output:

123.456

Alternatively, you can also use the BigDecimal.valueOf(double) method, which returns a BigDecimal whose value is equal to that of the specified double.

double value = 123.456;
BigDecimal bigDecimal = BigDecimal.valueOf(value);
System.out.println(bigDecimal);