January 2021
Intermediate to advanced
505 pages
9h 45m
Chinese
Content preview from PHP编程：第4版
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202
｜
第
8
章
Web
技术
文件上传
要处理文件上传（现代浏览器都支持），可以使用
$_FILES
数组。使用不同的认证和文件
上传函数，可以控制允许谁上传文件和文件上传后做什么处理。安全问题将在第
14
章
中进行讲解。
下面的代码展示了一个允许上传文件的页面 ：
<form enctype="multipart/form-data"
action="<?php echo $_SERVER['PHP_SELF']; ?>" method="POST">
<input type="hidden" name="MAX_FILE_SIZE" value="10240">
File name: <input name="toProcess" type="file" />
<input type="submit" value="Upload" />
</form>
文件上传最大的风险是文件太大无法处理。
PHP
有两种方式来预防这个问题 ：硬性限制
和软性限制。
php.ini
中的
upload_max_lesize
选项对上传文件的大小硬性设定了上限（默
认是
2MB
）。如果你在表单的文件字段参数前提交了一个名为
MAX_FILE_SIZE
的参数值，
PHP
会使用它作为软性限制。例如，在前面的例子中，上限设置为
10KB
。
PHP
会忽略
MAX_FILE_ SIZE
设置的比
upload_max_lesize
大的值。
注意，表单标签接受一个值为
"multipart/form-data"
的
enctype
属性。每个在
$_FILES ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.