直接贴代码吧！
public class CnNumberUtils {private final static Logger logger = LoggerFactory.getLogger(CnNumberUtils.class);//阿拉伯数字对应大写中文数字private final static String[] CN_NUMERALS = {"零", "壹", "贰", "叁", "肆", "伍", "陆", "柒", "捌", "玖"};//低单位private final static String[] CN_NUM_UNIT = {"", "拾", "佰", "仟"};//万元以上高单位private final static String[] CN_NUM_HIGHT_UNIT = {"", "万", "亿", "万亿"};//小数位单位private final static String[] CN_NUM_DECIMAL_UNIT = {"", "角", "分"};/*** 转换成中文大写金额（最高支持万亿和两位小数）* @param num* @return*/public static String toUppercase(Double num){return toUppercase(String.valueOf(num));}/*** 转换成中文大写金额（最高支持万亿和两位小数）* @param num* @return*/public static String toUppercase(String num){String[] strNumArray = num.split("\\.");int strNumArrayLength = strNumArray.length;if(strNumArrayLength > 2 || (strNumArrayLength == 2 && strNumArray[1].length() > 2)){logger.error("金额格式异常，不能有多个小数点，小数位最多只能两位！");}BigDecimal bigDecimal = new BigDecimal(strNumArray[0]);BigInteger bigInteger = bigDecimal.toBigInteger();char[] chars = bigInteger.toString().toCharArray();int intLength = chars.length;StringBuilder strBuilder = new StringBuilder();for(int i=0; i<intLength; i++){String curCnNum = CN_NUMERALS[charNumToInt(chars[i])];int ui = ((intLength-1)-i)%4;int hui = ((intLength-1)-i)/4;strBuilder.append(curCnNum);if(!isZero(curCnNum)){strBuilder.append(CN_NUM_UNIT[ui]);String heightUnit = CN_NUM_HIGHT_UNIT[hui];//如果剩余没有低金额单位或者后续都为零则加上高单位if(ui == 0 || isZeroInResidue(chars, i, ui)){strBuilder.append(heightUnit);//万单位以后的千单位如果不能为零则跳过零if(heightUnit.equals(CN_NUM_HIGHT_UNIT[1]) && !isZeroOfIndex(chars, (ui+1)+i)){i = i+skipZero(chars, i);}}}}clearZero(0, strBuilder);//小数位转换strBuilder.append("圆");if(strNumArrayLength == 1 || strNumArray[1].matches("^[0]*$")){strBuilder.append("整");return strBuilder.toString();}char[] decimalChars = strNumArray[1].toCharArray();int decimalCharLength = decimalChars.length;for(int i=1; i<=decimalCharLength; i++){String cnNum = CN_NUMERALS[charNumToInt(decimalChars[i-1])];if(!isZero(cnNum)){strBuilder.append(cnNum).append(CN_NUM_DECIMAL_UNIT[i]);}else if(i == decimalCharLength){return strBuilder.toString();}else{strBuilder.append(cnNum);}}return strBuilder.toString();}/*** 递归清除多余的零* @param startIndex* @param strBuilder*/private static void clearZero(int startIndex, StringBuilder strBuilder){int strLength = strBuilder.length();int zeroIndex = strBuilder.indexOf(CN_NUMERALS[0], startIndex);if(zeroIndex <= -1){return;}if(strLength <= zeroIndex+1){strBuilder.deleteCharAt(zeroIndex);return;}if(zeroIndex > -1 && isZero(strBuilder.charAt(zeroIndex+1))){strBuilder.deleteCharAt(zeroIndex);clearZero(startIndex, strBuilder);return;}if(strLength > zeroIndex+1){clearZero(zeroIndex+1, strBuilder);return;}}private static boolean isZero(String cnNum){return cnNum.equals(CN_NUMERALS[0]);}private static boolean isZero(char cnNum){return isZero(String.valueOf(cnNum));}/*** 跳过为零的下标* @param chars* @param beginIndex* @return*/private static int skipZero(char[] chars, int beginIndex){int newIndex = 0;int charLength = chars.length;for(int i=beginIndex+1; i<charLength; i++){if(isZero(CN_NUMERALS[charNumToInt(chars[i])])){newIndex++;}else{break;}}return newIndex;}/*** 指定下标值是否是为零* @param chars* @param index* @return boolean*/private static boolean isZeroOfIndex(char[] chars, int index){int numInex = Integer.parseInt(String.valueOf(chars[index]), 10);String cnNum = CN_NUMERALS[numInex];return isZero(cnNum);}/*** 从begin开始至end结束是否都是零* @param chars* @param begin* @param end* @return*/private static boolean isZeroInResidue(char[] chars, int begin, int end){for(int i=1; i<=end; i++){boolean r = isZeroOfIndex(chars, begin+i);if(!r){return false;}}return true;}/*** char类型数值转换为int* @param charNum* @return*/private static int charNumToInt(char charNum){String ns = String.valueOf(charNum);return Integer.parseInt(ns, 10);}}
技术要点：
金额字符长度-1-i（循环的当前索引）%4结果得出当前金额的小单位（十百千）。
金额字符长度-1-i（循环的当前索引）/4结果得出当前位金额大单位（万以上）。
例如：
10000元
长度5，-1-i（0）/4=1=单位万。
