让图片在高度确定的块元素中垂直居中

代码一：

示例一

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb18030" />
<title>Untitled Document</title>
<style type="text/css">
a{
    /* 以下行在标准浏览器必需,IE6可选 */
    display:table-cell;
    vertical-align:middle;
    width:300px;
    height:300px;

    /* 以下可选 */
    text-align:center;
    border:1px solid #CCC;
}
img{
    border:1px dotted #999;
}
</style>


</head>

<body>
    <a href="#" /><img src="http://img.baidu.com/img/img-jg.gif" /><span></span></a>
</body>
</html>

代码二：

示例二

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb18030" />
<title>Untitled Document</title>
<style type="text/css">
div.outer{
    width:300px;
    height:300px;

    /* 以下可选 */
    text-align:center;
    border:1px solid #CCC;
}
span{
    display:inline-block;
    line-height:300px;
    width:0px;
    visibility:hidden;
}
div.inner{
    display:inline-block;
    *display:inline;
    vertical-align:middle;
}
img{ border:1px dotted #CCC; }
</style>
</head>

<body>

<div class="outer">
    <span>.</span><div class="inner"><img src="http://img.baidu.com/img/img-jg.gif" /></div>
</div>

</body>
</html>

代码三：

代码

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb18030" />
<title>Untitled Document</title>
<style type="text/css">
.box {
        /*非IE的主流浏览器识别的垂直居中的方法*/
        display: table-cell;
        vertical-align:middle;

        /*设置水平居中*/
        text-align:center;

        /* 针对IE的Hack */
        *display: block;
        *font-size: 175px;/*约为高度的0.873，200*0.873 约为175*/
        *font-family:Arial;/*防止非utf-8引起的hack失效问题，如gbk编码*/

        width:200px;
        height:200px;
        border: 1px solid #eee;
}
.box img {
        /*设置图片垂直居中*/
        vertical-align:middle;
}
</style>
</head>

<body>

<div class="box">
    <img src="http://img.baidu.com/img/img-jg.gif" />
</div>

</body>
</html>