pinyin4j的java开源类库，提供中文转汉语拼音(并且支持多音字)
pinyin4j官方网址:http://pinyin4j.sourceforge.net/

import java.util.HashSet;
import java.util.Set;

import net.sourceforge.pinyin4j.PinyinHelper;
import net.sourceforge.pinyin4j.format.HanyuPinyinCaseType;
import net.sourceforge.pinyin4j.format.HanyuPinyinOutputFormat;
import net.sourceforge.pinyin4j.format.HanyuPinyinToneType;
import net.sourceforge.pinyin4j.format.HanyuPinyinVCharType;
import net.sourceforge.pinyin4j.format.exception.BadHanyuPinyinOutputFormatCombination;

public class pinyin4j {
 
 /**
  * 字符串集合转换字符串(逗号分隔)
  * @author wyh
  * @param stringSet
  * @return
  */
 public static String makeStringByStringSet(Set<String> stringSet){
  StringBuilder str = new StringBuilder();
  int i=0;
  for(String s : stringSet){
   if(i == stringSet.size() - 1){
    str.append(s);
   }else{
    str.append(s + ",");
   }
   i++;
  }
  return str.toString().toLowerCase();
 }
 
 /**
  * 获取拼音集合
  * @author wyh
  * @param src
  * @return Set<String>
  */
 public static Set<String> getPinyin(String src){
  if(src!=null && !src.trim().equalsIgnoreCase("")){
   char[] srcChar ;
   srcChar=src.toCharArray();
   //汉语拼音格式输出类
   HanyuPinyinOutputFormat hanYuPinOutputFormat = new HanyuPinyinOutputFormat();

//输出设置，大小写，音标方式等
   hanYuPinOutputFormat.setCaseType(HanyuPinyinCaseType.LOWERCASE); 
   hanYuPinOutputFormat.setToneType(HanyuPinyinToneType.WITHOUT_TONE)
   hanYuPinOutputFormat.setVCharType(HanyuPinyinVCharType.WITH_V);
   
   String[][] temp = new String[src.length()][];
   for(int i=0;i<srcChar.length;i++){
    char c = srcChar[i];
    //是中文或者a-z或者A-Z转换拼音(我的需求，是保留中文或者a-z或者A-Z)
    if(String.valueOf(c).matches("[\\u4E00-\\u9FA5]+")){
     try{
      temp[i] = PinyinHelper.toHanyuPinyinStringArray(srcChar[i], hanYuPinOutputFormat);
     }catch(BadHanyuPinyinOutputFormatCombination e) {
      e.printStackTrace();
     }
    }else if(((int)c>=65 && (int)c<=90) || ((int)c>=97 && (int)c<=122)){
     temp[i] = new String[]{String.valueOf(srcChar[i])};
    }else{
     temp[i] = new String[]{""};
    }
   }
   String[] pingyinArray = Exchange(temp);
   Set<String> pinyinSet = new HashSet<String>();
   for(int i=0;i<pingyinArray.length;i++){
    pinyinSet.add(pingyinArray[i]);
   }
   return pinyinSet;
  }
  return null;
 }
 
 /**
  * 递归
  * @author wyh
  * @param strJaggedArray
  * @return
  */
    public static String[] Exchange(String[][] strJaggedArray){
        String[][] temp = DoExchange(strJaggedArray);
        return temp[0];       
    }
   
    /**
     * 递归
     * @author wyh
     * @param strJaggedArray
     * @return
     */
    private static String[][] DoExchange(String[][] strJaggedArray){
        int len = strJaggedArray.length;
        if(len >= 2){           
            int len1 = strJaggedArray[0].length;
            int len2 = strJaggedArray[1].length;
            int newlen = len1*len2;
            String[] temp = new String[newlen];
            int Index = 0;
            for(int i=0;i<len1;i++){
                for(int j=0;j<len2;j++){
                    temp[Index] = strJaggedArray[0][i] + strJaggedArray[1][j];
                    Index ++;
                }
            }
            String[][] newArray = new String[len-1][];
            for(int i=2;i<len;i++){
                newArray[i-1] = strJaggedArray[i];                           
            }
            newArray[0] = temp;
            return DoExchange(newArray);
        }else{
         return strJaggedArray;   
        }
    }
   
 /**
  * @param args
  */
 public static void main(String[] args) {
  String str = "单田芳";
  System.out.println(makeStringByStringSet(getPinyin(str)));

}

}