小写数字转化为大写工具类

package test;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class CurrencyConverter {
    private static final double MAXIMUM_NUMBER = 9999999999999.99d;

    private static final String CN_ZERO = "零";
    private static final String CN_DOLLAR = "圆";
    private static final String CN_INTEGER = "整";

    private static final String[] digits = new String[] { "零", "壹", "贰", "叁",
            "肆", "伍", "陆", "柒", "捌", "玖" };
    private static final String[] radices = new String[] { "", "拾", "佰", "仟" };
    private static final String[] bigRadices = new String[] { "", "万", "亿", "万" };
    private static final String[] decimals = new String[] { "角", "分" };

    /**
     * 转换大写
     * 
     * @param currencyDigits
     * @return
     */
    public static String convert(String currencyDigits) {

        String integral = null; // 整数部分
        String decimal = null; // 小数部分
        String outputCharacters = null; // 最终转换输出结果

        String d = null;
        int zeroCount = 0, p = 0, quotient = 0, modulus = 0;

        // 删除数字中的逗号,
        currencyDigits = currencyDigits.replace("/,/g", "");
        // 删除数字左边的0
        currencyDigits = currencyDigits.replace("/^0+/", "");

        // 拆分数字中的整数与小数部分
        String[] parts = currencyDigits.split("\.");
        if (parts.length > 1) {
            integral = parts[0];
            decimal = parts[1];

            // 如果小数部分长度大于2，四舍五入，保留两位小数
            if (decimal.length() > 2) {
                long dd = Math.round(Double.parseDouble("0." + decimal) * 100);
                decimal = Long.toString(dd);
            }

        } else {
            integral = parts[0];
            decimal = "0";
        }

        // Start processing:
        outputCharacters = "";
        // Process integral part if it is larger than 0:
        if (Double.parseDouble(integral) > 0) {

            zeroCount = 0;

            for (int i = 0; i < integral.length(); i++) {

                p = integral.length() - i - 1;
                d = integral.substring(i, i + 1);

                quotient = p / 4;
                modulus = p % 4;
                if (d.equals("0")) {
                    zeroCount++;
                } else {
                    if (zeroCount > 0) {
                        outputCharacters += digits[0];
                    }
                    zeroCount = 0;
                    outputCharacters += digits[Integer.parseInt(d)]
                            + radices[modulus];
                }
                if (modulus == 0 && zeroCount < 4) {
                    outputCharacters += bigRadices[quotient];
                }
            }
            outputCharacters += CN_DOLLAR;
        }

        // Process decimal part if it is larger than 0:
        if (Double.parseDouble(decimal) > 0) {
            for (int i = 0; i < decimal.length(); i++) {
                d = decimal.substring(i, i + 1);
                if (!d.equals("0")) {
                    outputCharacters += digits[Integer.parseInt(d)]
                            + decimals[i];
                } else {
                    if (i == 0) {
                        outputCharacters += CN_ZERO;
                    }
                }
            }
        }

        // Confirm and return the final output string:
        if (outputCharacters.equals("")) {
            outputCharacters = CN_ZERO + CN_DOLLAR;
        }
        if (decimal == null || decimal.equals("0")) {
            outputCharacters += CN_INTEGER;
        }

        outputCharacters = "" + outputCharacters;
        return outputCharacters;
    }

    /**
     * 检查输入数字的合法性
     * 
     * @param currencyDigits
     * @return
     */
    public static boolean check(final String currencyDigits) {
        if (currencyDigits == null || currencyDigits.trim().equals("")) {
            System.out.println("没有输入要转换的数字");
            return false;
        }

        Pattern pattern = Pattern.compile("/[^,.\d]/",
                Pattern.CASE_INSENSITIVE);
        Matcher matcher = pattern.matcher(currencyDigits);

        if (matcher.find()) {
            System.out.println("数字中含有非法字符!");
            return false;
        }

        pattern = Pattern
                .compile(
                        "/^((\d{1,3}(,\d{3})*(.((\d{3},)*\d{1,3}))?)|(\d+(.\d+)?))$/",
                        Pattern.CASE_INSENSITIVE);
        matcher = pattern.matcher(currencyDigits);
        if (matcher.find()) {
            System.out.println("错误的数字格式!");
            return false;
        }

        if (Double.parseDouble(currencyDigits) > MAXIMUM_NUMBER) {
            System.out.println("超出转换最大范围!");
            return false;
        }

        return true;
    }
}

调用

package test;

import java.math.BigDecimal;

public class xiaoda {

  /**
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    Double a=6.5;String priDebtAmount = null;
    BigDecimal b = new BigDecimal(a).multiply(new BigDecimal(10000));
    Boolean nav = CurrencyConverter.check(a.toString());// 判断输入的合法性
    if (nav) {
      priDebtAmount = CurrencyConverter.convert(b.toString());
    }
    System.out.println(priDebtAmount);//陆万伍仟圆整
  }

}