方法1：
在html表单，放置多个文件选择框， 使用数组名作为组件的名字，如下：
<form action="upload.php" method="post" enctype="multipart/form-data">
<input type="file" name="upfile[]"/>
<input type="file" name="upfile[]"/>
<input type="file" name="upfile_2[]"/>
<input type="file" name="upfile_2[]"/>
</form>
在服务器端我们可以测试一下提交的信息
<?php
print_r($_FILES);
?>
输出结果：
Array
(
[upfile] => Array
(
[name] => Array
(
[0] => C函数速查.chm
[1] => JDK_API_1_6中文帮助.CHM
) [type] => Array
(
[0] => application/octet-stream
[1] => application/octet-stream
) [tmp_name] => Array
(
[0] => D:\PHP\xampp2\tmp\phpF7E1.tmp
[1] => D:\PHP\xampp2\tmp\phpF7E2.tmp
) [error] => Array
(
[0] => 0
[1] => 0
) [size] => Array
(
[0] => 98791
[1] => 36830335
) ) [upfile_2] => Array
(
[name] => Array
(
[0] => jquery1.7.2中文手册.chm
[1] => jQuery1.8.3中文手册.chm
) [type] => Array
(
[0] => application/octet-stream
[1] => application/octet-stream
) [tmp_name] => Array
(
[0] => D:\PHP\xampp2\tmp\phpF93A.tmp
[1] => D:\PHP\xampp2\tmp\phpF93B.tmp
) [error] => Array
(
[0] => 0
[1] => 0
) [size] => Array
(
[0] => 306357
[1] => 405941
) ) )
方法2：
在html端为每一个input框给一个不同的name
<form action="upload.php" method="post" enctype="multipart/form-data">
<input type="file" name="upfile_1"/>
<input type="file" name="upfile_2"/>
<input type="file" name="upfile_3"/>
</form>
服务端“print_r($_FILES);” 后，输出的信息：
Array
(
[upfile_1] => Array
(
[name] => C函数速查.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\php2247.tmp
[error] => 0
[size] => 98791
) [upfile_2] => Array
(
[name] => JDK_API_1_6中文帮助.CHM
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\php2248.tmp
[error] => 0
[size] => 36830335
) [upfile_3] => Array
(
[name] => jquery1.7.2中文手册.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\php23B0.tmp
[error] => 0
[size] => 306357
) )
所以，针对下面这个“综合性”上传表单：
<form action="upload.php" method="post" enctype="multipart/form-data" >
<input type="file" name="upfile[]"/>
<input type="file" name="upfile[]"/>
<input type="file" name="upfile_2[]"/>
<input type="file" name="upfile_2[]"/>
<input type="file" name="upfile_3"/>
<input type="file" name="upfile_4"/>
</form>
服务端接收到的数据为：
Array
(
[upfile] => Array
(
[name] => Array
(
[0] => C函数速查.chm
[1] => JDK_API_1_6中文帮助.CHM
) [type] => Array
(
[0] => application/octet-stream
[1] => application/octet-stream
) [tmp_name] => Array
(
[0] => D:\PHP\xampp2\tmp\php4440.tmp
[1] => D:\PHP\xampp2\tmp\php4441.tmp
) [error] => Array
(
[0] => 0
[1] => 0
) [size] => Array
(
[0] => 98791
[1] => 36830335
) ) [upfile_2] => Array
(
[name] => Array
(
[0] => jquery1.7.2中文手册.chm
[1] => jQuery1.8.3中文手册.chm
) [type] => Array
(
[0] => application/octet-stream
[1] => application/octet-stream
) [tmp_name] => Array
(
[0] => D:\PHP\xampp2\tmp\php459A.tmp
[1] => D:\PHP\xampp2\tmp\php459B.tmp
) [error] => Array
(
[0] => 0
[1] => 0
) [size] => Array
(
[0] => 306357
[1] => 405941
) ) [upfile_3] => Array
(
[name] => php_manual_zh.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\php459C.tmp
[error] => 0
[size] => 31019182
) [upfile_4] => Array
(
[name] => TIPI深入理解PHP内核_2014-04-29_V0.8.3.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\php4687.tmp
[error] => 0
[size] => 1304181
) )
问题：上面的 $_FILES 信息有点乱，可以写个函数/方法来格式化下，参考代码如下：
function format_files($files)
{
$fileArray = array();
$n = 0;
foreach ($files as $key => $file)
{
if (is_array($file['name']))
{
$keys = array_keys($file);
$count = count($file['name']);
for ($i = 0; $i < $count; $i++)
{
$fileArray[$n]['key'] = $key;
foreach ($keys as $_key)
{
$fileArray[$n][$_key] = $file[$_key][$i];
}
$n++;
}
}
else
{
$fileArray[$n] = $file;
$fileArray[$n]['key'] = $key;
$n++;
}
} return $fileArray;
}
经过 format_files($_FILES); 处理后，结果被格式化为：
Array
(
[0] => Array
(
[key] => upfile
[name] => C函数速查.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF27F.tmp
[error] => 0
[size] => 98791
) [1] => Array
(
[key] => upfile
[name] => JDK_API_1_6中文帮助.CHM
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF280.tmp
[error] => 0
[size] => 36830335
) [2] => Array
(
[key] => upfile_2
[name] => jquery1.7.2中文手册.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF3C9.tmp
[error] => 0
[size] => 306357
) [3] => Array
(
[key] => upfile_2
[name] => jQuery1.8.3中文手册.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF3CA.tmp
[error] => 0
[size] => 405941
) [4] => Array
(
[name] => php_manual_zh.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF3CB.tmp
[error] => 0
[size] => 31019182
[key] => upfile_3
) [5] => Array
(
[name] => TIPI深入理解PHP内核_2014-04-29_V0.8.3.chm
[type] => application/octet-stream
[tmp_name] => D:\PHP\xampp2\tmp\phpF4C6.tmp
[error] => 0
[size] => 1304181
[key] => upfile_4
) )
延伸阅读：