分享一段PHP制作的中文拼音首字母工具类

<?php
/**
* 汉字拼音首字母工具类
*  注： 英文的字串：不变返回(包括数字)    eg .abc123 => abc123
*      中文字符串：返回拼音首字符        eg. 测试字符串 => cszfc
*      中英混合串: 返回拼音首字符和英文   eg. 我i我j => wiwj
*  eg.
*  $py = new str2py();
* 
*  $result = $py->getinitials('周杰伦');
*
*  //获取首字母
*  $result = $py->getfirststring('abc');  //a
*  $resutl = $py->getfirststring("周杰伦"); //z
*
*/
class str2py
{
    private $_pinyins = array(
=> 'a',
=> 'b',
=> 'c',
=> 'd',
=> 'e',
=> 'f',
=> 'g',
=> 'h',
=> 'j',
=> 'k',
=> 'l',
=> 'm',
=> 'n',
=> 'o',
=> 'p',
=> 'q',
=> 'r',
=> 's',
=> 't',
=> 'w',
=> 'x',
=> 'y',
=> 'z',
    );
    private $_charset = null;
    /**
     * 构造函数, 指定需要的编码 default: utf-8
     * 支持utf-8, gb2312
     *
     * @param unknown_type $charset
     */
    public function __construct($charset = 'utf-8')
    {
        $this->_charset = $charset;
    }
    /**
     * 中文字符串 substr
     *
     * @param string $str
     * @param int    $start
     * @param int    $len
     * @return string
     */
    private function _msubstr($str, $start, $len)
    {
        $start = $start * 2;
        $len = $len * 2;
        $strlen = strlen($str);
        $result = '';
        for ($i = 0; $i < $strlen; $i++)
        {
            if ($i >= $start && $i < ($start + $len))
            {
                if (ord(substr($str, $i, 1)) > 129)
                {
                    $result .= substr($str, $i, 2);
                }
                else
                {
                    $result .= substr($str, $i, 1);
                }
            }
            if (ord(substr($str, $i, 1)) > 129)
            {
                $i++;
            }
        }
        return $result;
    }
    /**
     * 字符串切分为数组 (汉字或者一个字符为单位)
     *
     * @param string $str
     * @return array
     */
    private function _cutword($str)
    {
        $words = array();
        while ($str != "")
        {
            if ($this->_isascii($str))
            {/* 非中文 */
                $words[] = $str[0];
                $str = substr($str, strlen($str[0]));
            }
            else
            {
                $word = $this->_msubstr($str, 0, 1);
                $words[] = $word;
                $str = substr($str, strlen($word));
            }
        }
        return $words;
    }
    /**
     * 判断字符是否是ascii字符
     *
     * @param string $char
     * @return bool
     */
    private function _isascii($char)
    {
        return ( ord(substr($char, 0, 1)) < 160 );
    }
    /**
     * 判断字符串前3个字符是否是ascii字符
     *
     * @param string $str
     * @return bool
     */
    private function _isasciis($str)
    {
        $len = strlen($str) >= 3 ? 3 : 2;
        $chars = array();
        for ($i = 1; $i < $len - 1; $i++)
        {
            $chars[] = $this->_isascii($str[$i]) ? 'yes' : 'no';
        }
        $result = array_count_values($chars);
        if (empty($result['no']))
        {
            return true;
        }
        return false;
    }
    /**
     * 获取中文字串的拼音首字符
     *
     * @param string $str
     * @return string
     */
    public function getinitials($str)
    {
        if (empty($str))
            return '';
        if ($this->_isascii($str[0]) && $this->_isasciis($str))
        {
            return $str;
        }
        $result = array();
        if ($this->_charset == 'utf-8')
        {
            $str = iconv('utf-8', 'gb2312', $str);
        }
        $words = $this->_cutword($str);
        foreach ($words as $word)
        {
            if ($this->_isascii($word))
            {/* 非中文 */
                $result[] = $word;
                continue;
            }
            $code = ord(substr($word, 0, 1)) * 1000 + ord(substr($word, 1, 1));
            /* 获取拼音首字母a--z */
            if (($i = $this->_search($code)) != -1)
            {
                $result[] = $this->_pinyins[$i];
            }
        }
        return strtoupper(implode('', $result));
    }
    /**
     *  20140624 wangtianbao 获取首字母
     *  @param string $str
     *  @return string
     */
    public function getfirststring($str)
    {
        //先把中文转换成字母
        $new_string = $this->getinitials($str);
        if (empty($new_string))
        {
            return '';
        }
        else
        {
            return strtoupper(substr($new_string, 0, 1));
        }
    }
    private function _getchar($ascii)
    {
        if ($ascii >= 48 && $ascii <= 57)
        {
            return chr($ascii);  /* 数字 */
        }
        elseif ($ascii >= 65 && $ascii <= 90)
        {
            return chr($ascii);   /* a--z */
        }
        elseif ($ascii >= 97 && $ascii <= 122)
        {
            return chr($ascii - 32); /* a--z */
        }
        else
        {
            return '-'; /* 其他 */
        }
    }
    /**
     * 查找需要的汉字内码(gb2312) 对应的拼音字符( 二分法 )
     *
     * @param int $code
     * @return int
     */
    private function _search($code)
    {
        $data = array_keys($this->_pinyins);
        $lower = 0;
        $upper = sizeof($data) - 1;
        $middle = (int) round(($lower + $upper) / 2);
        if ($code < $data[0])
            return -1;
        for (;;)
        {
            if ($lower > $upper)
            {
                return $data[$lower - 1];
            }
            $tmp = (int) round(($lower + $upper) / 2);
            if (!isset($data[$tmp]))
            {
                return $data[$middle];
            }
            else
            {
                $middle = $tmp;
            }
            if ($data[$middle] < $code)
            {
                $lower = (int) $middle + 1;
            }
            else if ($data[$middle] == $code)
            {
                return $data[$middle];
            }
            else
            {
                $upper = (int) $middle - 1;
            }
        }
    }
}