两种方式：
一.使用第三方jar包

1.首先引入一个拼音转换的包，在maven库里是存在的，也可以到网上去下。
<dependency>
<groupId>com.belerweb</groupId>
<artifactId>pinyin4j</artifactId>
<version>2.5.0</version>
</dependency>

2.代码
package test;
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 GetPingYin {

    /**  * 得到 全拼  * @param src  * @return  */
public static String getPingYin(String src) {
    char[] t1 = null;
    t1 = src.toCharArray();
    String[] t2 = new String[t1.length];
    HanyuPinyinOutputFormat t3 = new HanyuPinyinOutputFormat();
    t3.setCaseType(HanyuPinyinCaseType.LOWERCASE);
    t3.setToneType(HanyuPinyinToneType.WITHOUT_TONE);
    t3.setVCharType(HanyuPinyinVCharType.WITH_V);
    String t4 = "";
    int t0 = t1.length;
    try {
        for (int i = 0; i < t0; i++) {
            // 判断是否为汉字字符
            if (java.lang.Character.toString(t1[i]).matches("[\\u4E00-\\u9FA5]+")) {
                t2 = PinyinHelper.toHanyuPinyinStringArray(t1[i], t3);
                t4 += t2[0];
            } else {
                t4 += java.lang.Character.toString(t1[i]);
            }
        }
        return t4;
    } catch (BadHanyuPinyinOutputFormatCombination e1) {
        e1.printStackTrace();
    }
    return t4;
}
        /**  * 得到中文首字母  * @param str  * @return  */
public static String getPinYinHeadChar(String str) {
    String convert = "";
    for (int j = 0; j < str.length(); j++) {
        char word = str.charAt(j);
        String[] pinyinArray = PinyinHelper.toHanyuPinyinStringArray(word);
        if (pinyinArray != null) {
            convert += pinyinArray[0].charAt(0);
        } else {
            convert += word;
        }
    }
    return convert;
}
        /**  * 将字符串转移为ASCII码  *  * @param cnStr  * @return  */
public static String getCnASCII(String cnStr) {
    StringBuffer strBuf = new StringBuffer();
    byte[] bGBK = cnStr.getBytes();
    for (int i = 0; i < bGBK.length; i++) {
        strBuf.append(Integer.toHexString(bGBK[i] & 0xff));
    }
    return strBuf.toString();
}
public static void main(String[] args) {
    String cnStr = "芈月";
    System.out.println(getPingYin(cnStr).toUpperCase());
    System.out.println(getPinYinHeadChar(cnStr).toUpperCase());
}

}

3.输出结果
MIYUE
MY

二.
package cn.crhms.cp.his.storage.storagebizservice.controller.adjustprice;
import java.io.UnsupportedEncodingException;

public class testsss {

private final static int[] li_SecPosValue = {1601, 1637, 1833, 2078, 2274,
        2302, 2433, 2594, 2787, 3106, 3212, 3472, 3635, 3722, 3730, 3858,
        4027, 4086, 4390, 4558, 4684, 4925, 5249, 5590};
private final static String[] lc_FirstLetter = {"a", "b", "c", "d", "e",
        "f", "g", "h", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s",
        "t", "w", "x", "y", "z"};


public static String getAllFirstLetter(String str) {
    if (str == null || str.trim().length() == 0) {
        return "";
    }

    String _str = "";
    for (int i = 0; i < str.length(); i++) {
        _str = _str + getFirstLetter(str.substring(i, i + 1));
        System.out.println(_str);
    }

    return _str;
}


public static String getFirstLetter(String chinese) {
    if (chinese == null || chinese.trim().length() == 0) {
        return "";
    }
    chinese = conversionStr(chinese, "GB2312", "ISO8859-1");
    if (chinese.length() > 1) // 判断是不是汉字
    {
        int li_SectorCode = (int) chinese.charAt(0); // 汉字区码
        int li_PositionCode = (int) chinese.charAt(1); // 汉字位码

        li_SectorCode = li_SectorCode - 160;
        li_PositionCode = li_PositionCode - 160;

        int li_SecPosCode = li_SectorCode * 100 + li_PositionCode; // 汉字区位码
        if (li_SecPosCode > 1600 && li_SecPosCode < 5590) {
            for (int i = 0; i < 23; i++) {
                if (li_SecPosCode >= li_SecPosValue[i]
                        && li_SecPosCode < li_SecPosValue[i + 1]) {
                    chinese = lc_FirstLetter[i];
                    break;
                }
            }
        } else // 非汉字字符,如图形符号或ASCII码
        {
            chinese = conversionStr(chinese, "ISO8859-1", "GB2312");
            chinese = chinese.substring(0, 1);
        }
    }

    return chinese;
}


private static String conversionStr(String str, String charsetName, String toCharsetName) {
    try {
        str = new String(str.getBytes(charsetName), toCharsetName);
    } catch (UnsupportedEncodingException ex) {
        System.out.println("字符串编码转换异常：" + ex.getMessage());
    }
    return str;
}


public static void main(String[] args) {
    System.out.println("获取拼音首字母：" + getAllFirstLetter("我副才").toUpperCase());
    System.out.println("获取拼音首字母：" + getFirstLetter("我"));
}

}