工作中用到的，觉得这样的显示工作，还是交给模板类比较合适。所以写了这样的一个插件。

 

<?php
/**
 * Smarty plugin
 * @package Smarty
 * @subpackage plugins
 */

/**
 * Smarty email_mask modifier plugin
 *
 * Type:     modifier<br>
 * Name:     email_mask<br>
 * Purpose:  mask part of email<br>
 * Input:<br>
 *         - string: input email
 *         - part: mask part [default '60'] unit: percent
 *         - position: mask position [default 'center'] (left, center, right)
 *         - maskString: mask string [default '*']
 *
 * @author  wendaming <wendaming at comsenz dot com>
 * @param string
 * @param integer
 * @param string
 * @param string
 * @return string|void
 */

function smarty_modifier_email_mask($string, $maskPart = 60, $position = 'center', $maskString = '*') {
    $emailName = substr($string, 0, strpos($string, '@'));
    $emailLen = strlen($emailName);
    $maskNum = floor($emailLen * $maskPart / 100);
    $maskName = '';

    if ($position == 'center') {
        $beginMask = floor(($emailLen - $maskNum) / 2);
    } elseif ($position == 'left') {
        $beginMask = 0;
    } else {
        $beginMask = $emailLen - $maskNum;
    }

    $count = 0;
    for ($i = 0; $i < $emailLen; ++ $i) {
        if ($i >= $beginMask && $count < $maskNum) {
            $maskName .= $maskString;
            ++ $count;
        } else {
            $maskName .= $emailName{$i};
        }
    }

    return str_replace($emailName . '@', $maskName . '@', $string);
}