JAVA功能代码-字符串提取首字母

import java.io.UnsupportedEncodingException;

public class ChineseToEn {
    private final static int[] 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[] firstLetter = {
        "a","b","c","d","e","f","g","h",
        "j","k","l","m","n","o","p","q",
        "r","s","t","w","x","y","z"
    };

    /**
     * 获取所有汉字首字母
     * @param str
     * @return
     */
    public String getAllFirstLetter(String str){
        if (str == null || str.trim().length() == 0){
            return "";
        }
        String _str = "";
        for (int i = 0; i < str.length(); i++) {
            _str = _str + this.getFirstLetter(str.substring(i,i+1));
        }
        return _str;
    }

    /**
     * 获取第一个汉字首字母
     * @param str
     * @return
     */
    private String getFirstLetter(String str) {
        if (str == null || str.trim().length() == 0){
            return "";
        }
        str = this.conversionStr(str,"GB2312","ISO8859-1");
        if (str.length() > 1){
            int sectorCode =(int)str.charAt(0);
            int positionCode = (int)str.charAt(1);
            sectorCode = sectorCode - 160;
            positionCode = positionCode - 160;
            int secPosCode = sectorCode * 100 + positionCode;
            if(secPosCode > 1600 && secPosCode < 5590){
                for (int i = 0; i < 23; i++) {
                    if (secPosCode >= secPosValue[i] && secPosCode < secPosValue[i+1]){
                        str = firstLetter[i];
                        break;
                    }
                }
            }else {
                str  =this.conversionStr(str, "ISO8859-1","GB2312");
                str = str.substring(0,1);
            }
        }
        return str;
    }

    /**
     * 转换编码
     * @param str
     * @param oldchartset
     * @param chartset
     * @return
     */
    private String conversionStr(String str, String oldchartset, String chartset) {
        try {
            str = new String(str.getBytes(oldchartset),chartset);
        }catch (UnsupportedEncodingException e){
            System.out.println("转换编码异常"+e.getMessage());
        }
        return str;
    }
}