添加maven依赖

        <dependency>
            <groupId>com.belerweb</groupId>
            <artifactId>pinyin4j</artifactId>
            <version>2.5.0</version>
        </dependency>

也可以自己自己下载jar包

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;


/**
 * 
 * 
 * @author  / zhangzihao
 * 
 */
public class StringPinYinCodeUtil {

    /**
     * 根据字符串得到该字符串首写的拼音码【字符串不能为空,替换掉空格】
     * @param code
     * @return
     */
    public static String getConvertCode(String strName) {

        String replaceCode = strName.replace(" ", "");
        String subStr = replaceCode;
        if (subStr.length() > 12) {
            subStr = subStr.substring(0, 12);
        }
        String resultCode = getPinYinHeadChar(subStr);
        return resultCode;
    }

    /**
     * 将汉字转换为全拼
     * 
     * @param src
     * @return String
     */
    public static String getPinYin(String src) {
        char[] t1 = null;
        t1 = src.toCharArray();
        // System.out.println(t1.length);  
        String[] t2 = new String[t1.length];
        // System.out.println(t2.length);  
        // 设置汉字拼音输出的格式  
        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  
                // System.out.println(t1[i]);  
                if (Character.toString(t1[i]).matches("[\\u4E00-\\u9FA5]+")) {
                    t2 = PinyinHelper.toHanyuPinyinStringArray(t1[i], t3);// 将汉字的几种全拼都存到t2数组中  
                    t4 += t2[0];// 取出该汉字全拼的第一种读音并连接到字符串t4后  
                } else {
                    // 如果不是汉字字符,直接取出字符并连接到字符串t4后  
                    t4 += Character.toString(t1[i]);
                }
            }
        } catch (BadHanyuPinyinOutputFormatCombination e) {
            // TODO Auto-generated catch block  
            e.printStackTrace();
        }
        return t4;
    }

    /**
     * 提取每个汉字的首字母
     * 
     * @param str
     * @return String
     */
    public static String getPinYinHeadChar(String str) {
        String convert = "";
        for (int j = 0; j < str.length(); j++) {
            char word = str.charAt(j);
            // 提取汉字的首字母  
            String[] pinyinArray = PinyinHelper.toHanyuPinyinStringArray(word);
            if (pinyinArray != null) {
                convert += pinyinArray[0].charAt(0);
            } else {
                convert += word;
            }
        }
        return convert;
    }

    /**
     * 将字符串转换成ASCII码
     * 
     * @param cnStr
     * @return String
     */
    public static String getCnASCII(String cnStr) {
        StringBuffer strBuf = new StringBuffer();
        // 将字符串转换成字节序列  
        byte[] bGBK = cnStr.getBytes();
        for (int i = 0; i < bGBK.length; i++) {
            // System.out.println(Integer.toHexString(bGBK[i] & 0xff));  
            // 将每个字符转换成ASCII码  
            strBuf.append(Integer.toHexString(bGBK[i] & 0xff) + " ");
        }
        return strBuf.toString();
    }

}

测试用例:

String code = StringPinYinCodeUtil.getPinYinHeadChar("转化的字符串");