分享一段PHP制作的中文拼音首字母工具类

代码很简单，这里就不多BB了，大家看注释吧，注释都看不懂的小伙伴，求放过PHP！！！

<?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;

            }

        }

    }

}

取汉字首字母算是目前几乎没个项目中都需要用到的功能了，这里给大家推荐的是效率比较高的代码，也是在本人项目中使用的，小伙伴们如发现问题，还请留言，大家共同进步