文件上传是所有web利用中最常见的性能，而PHP实现这一性能也十分的简略，只须要前端设置表单的 enctype 值为 multipart/form-data 之后，咱们就能够通过 $_FILES 取得表单中的 file 控件中的内容。
同时，咱们还能够将 file 控件的名称写成带 [] 的数组模式，这样咱们就能够接管到多个上传的文件。比方上面这个测试用的表单：
<!DOCTYPE html><html lang="en"><head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Document</title></head><body> <form action="" enctype="multipart/form-data" method="post"> myfile1：<input type="file" name="myfile[]"/><br/> myfile2：<input type="file" name="myfile[a][]"/><br/> myfile3：<input type="file" name="myfile[a][b][]"/><br/> myfile4：<input type="file" name="myfile[c][]"/><br/> myfile5：<input type="file" name="myfile[]"/><br/> myfile6：<input type="file" name="myfile[][]"/><br/> <br/> newfile1：<input type="file" name="newfile[][]"/><br/> newfile2：<input type="file" name="newfile[s]"/><br/> singlefile: <input type="file" name="singlefile"/><br/> <input type="submit" value="submit"/> </form></body></html>一共有9个 file 控件，其中 myfile 和 newfile 都是数组类型的表单名，而 singlefile 则是一个独自的。先简略的看一下 $_FILES 所取得的内容。
print_r($_FILES);Array( [myfile] => Array ( [name] => Array ( [0] => 2591d8b3eee018a0a84f671933ab6c74.png [a] => Array ( [0] => 12711584942474_.pic_hd 1.jpg [b] => Array ( [0] => 12721584942474_.pic_hd 1.jpg ) ) [c] => Array ( [0] => 12731584942474_.pic_hd.jpg ) [1] => background1.jpg [2] => Array ( [0] => adliu_pip_data.xlsx ) ) [type] => Array ( [0] => image/png [a] => Array ( [0] => image/jpeg [b] => Array ( [0] => image/jpeg ) ) [c] => Array ( [0] => image/jpeg ) [1] => image/jpeg [2] => Array ( [0] => application/vnd.openxmlformats-officedocument.spreadsheetml.sheet ) ) [tmp_name] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phphD88ZY [a] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpNY8MzY [b] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/php3MX5tk ) ) [c] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpjgrHMj ) [1] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phppXRtnc [2] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpekSY1M ) ) [error] => Array ( [0] => 0 [a] => Array ( [0] => 0 [b] => Array ( [0] => 0 ) ) [c] => Array ( [0] => 0 ) [1] => 0 [2] => Array ( [0] => 0 ) ) [size] => Array ( [0] => 4973 [a] => Array ( [0] => 3007 [b] => Array ( [0] => 1156 ) ) [c] => Array ( [0] => 6068 ) [1] => 393194 [2] => Array ( [0] => 36714 ) ) ) [newfile] => Array ( [name] => Array ( [0] => Array ( [0] => 数据列表 (2).xlsx ) [s] => background1.jpg ) [type] => Array ( [0] => Array ( [0] => application/vnd.openxmlformats-officedocument.spreadsheetml.sheet ) [s] => image/jpeg ) [tmp_name] => Array ( [0] => Array ( [0] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phplSsRfM ) [s] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpuQAvRb ) [error] => Array ( [0] => Array ( [0] => 0 ) [s] => 0 ) [size] => Array ( [0] => Array ( [0] => 77032 ) [s] => 393194 ) ) [singlefile] => Array ( [name] => timg (8).jpeg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpxtSQ4J [error] => 0 [size] => 10273 ))看出有什么问题了吗？
$_FILE['singlefile']['name'];$_FILE['singlefile']['type'];$_FILE['singlefile']['tmp_name'];$_FILE['singlefile']['error'];$_FILE['singlefile']['error'];$_FILE['myfile']['name']['a']['b'][0];$_FILE['myfile']['type']['a']['b'][0];$_FILE['myfile']['tmp_name']['a']['b'][0];$_FILE['myfile']['error']['a']['b'][0];$_FILE['myfile']['error']['a']['b'][0];单个表单是一个 singlefile 为键名的数组，外面是对应的 name 、 type 等属性。这个非常简单也清晰明了，然而数组模式上传的内容就比拟坑了，每一个属性上面都有多个值，而且这些值还有可能是嵌套的数组。就比如说咱们要取得 myfilea[] 的上传文件内容，咱们就要通过 \$_FILE'myfile''a'[0] 、 $_FILE['myfile']['type']['a']['b'][0] 这样的模式取得相干的内容。这个可真的不是很敌对，那么咱们明天的主题就来了，咱们把这种内容进行一下格式化，让他变成和 singlefile 相似的构造，也就是一个文件的相干内容都在一个键名构造下，比方 myfile[a][b][] 的内容就全副都在 $_FILE'myfile'b上面。
$files = [];// 开始数据格式化foreach ($_FILES as $uploadKey => $uploadFiles) { // 须要将 $_FILES 中的五个字段都拿进去 $files[$uploadKey] = formatUploadFiles($uploadFiles['name'], $uploadFiles['type'], $uploadFiles['tmp_name'], $uploadFiles['error'], $uploadFiles['size']);}// 格式化上传文件数组function formatUploadFiles($fileNamesArray, $type, $tmp_name, $error, $size){ $tmpFiles = []; // 文件名是否是数组，如果不是数组，就是单个文件上传 if (is_array($fileNamesArray)) { // 数组模式上传 foreach ($fileNamesArray as $idx => $fileName) { // 如果还是嵌套的数组，递归遍历接下来的内容 if (is_array($fileName)) { $tmpFiles[$idx] = formatUploadFiles($fileName, $type[$idx] ?? [], $tmp_name[$idx] ?? [], $error[$idx] ?? [], $size[$idx] ?? []); } else { // 组合多维的格式化内容 $tmpFiles[$idx] = [ 'name' => $fileName, 'type' => $type[$idx] ?? '', 'tmp_name' => $tmp_name[$idx] ?? '', 'error' => $error[$idx] ?? '', 'size' => $size[$idx] ?? '', ]; } } } else { // 组合单个的内容 $tmpFiles = [ 'name' => $fileName, 'type' => $type ?? '', 'tmp_name' => $tmp_name ?? '', 'error' => $error ?? '', 'size' => $size ?? '', ]; } return $tmpFiles;}print_r($files);代码还是十分好了解的，就是通过一段递归来遍历整个 $_FILES 目录树，相当于一个深度遍历。当然，这样也会带来性能的降落，毕竟是须要进行循环+递归的遍历。不过好在大部分状况下咱们上传的文件并不会那么的多。不过反过来说，如果不当时进行格式化，当你想取得所有的上传内容时，一样还是须要进行多层或者递归遍历的。
接下来咱们看看格式化之后的输入：
Array( [myfile] => Array ( [0] => Array ( [name] => 2591d8b3eee018a0a84f671933ab6c74.png [type] => image/png [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpV7A2yC [error] => 0 [size] => 4973 ) [a] => Array ( [0] => Array ( [name] => 12711584942474_.pic_hd 1.jpg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/php5q2d1Z [error] => 0 [size] => 3007 ) [b] => Array ( [0] => Array ( [name] => 12721584942474_.pic_hd 1.jpg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpdvv8No [error] => 0 [size] => 1156 ) ) ) [c] => Array ( [0] => Array ( [name] => 12731584942474_.pic_hd.jpg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/php9tfGmp [error] => 0 [size] => 6068 ) ) [1] => Array ( [name] => background1.jpg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phplUVpzA [error] => 0 [size] => 393194 ) [2] => Array ( [0] => Array ( [name] => adliu_pip_data.xlsx [type] => application/vnd.openxmlformats-officedocument.spreadsheetml.sheet [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpNRtiaC [error] => 0 [size] => 36714 ) ) ) [newfile] => Array ( [0] => Array ( [0] => Array ( [name] => 数据列表 (2).xlsx [type] => application/vnd.openxmlformats-officedocument.spreadsheetml.sheet [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpBLG7aG [error] => 0 [size] => 77032 ) ) [s] => Array ( [name] => background1.jpg [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpjyqCFY [error] => 0 [size] => 393194 ) ) [singlefile] => Array ( [name] => [type] => image/jpeg [tmp_name] => /private/var/folders/wj/t2z1cfhs0m9gq48krm8nc0vm0000gn/T/phpuYJXiE [error] => 0 [size] => 10273 ))和下面原始的 $_FILES 相比是不是清晰明了的很多？这回咱们如果须要 myfilea[] 外面全副的内容时，就能够应用上面的形式不便的获取了：
$files['myfile']['a']['b'][0]['name'];$files['myfile']['a']['b'][0]['type'];$files['myfile']['a']['b'][0]['tmp_name'];$files['myfile']['a']['b'][0]['error'];$files['myfile']['a']['b'][0]['size'];当然，这种需要在咱们的日常工作中并不多见，这里也只是提供一个思路，将数据提前转化成咱们须要的格局是一种十分好的习惯，可能让咱们的后续操作变得非常简单。
测试代码：
https://github.com/zhangyue0503/dev-blog/blob/master/php/202004/source/PHP%E5%A4%9A%E6%96%87%E4%BB%B6%E4%B8%8A%E4%BC%A0%E6%A0%BC%E5%BC%8F%E5%8C%96.php
参考文档：
https://www.php.net/manual/zh/features.file-upload.php
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