25行实现文件上传功能（PHP）

 1 <form action="#" method="post" enctype="multipart/form-data">
 2     <label for="file">file:</label>
 3     <input type="file" name="file" id="file"/><br/>
 4     <input type="submit" name="submit" value="submit">
 5 </form>
 6 <?php
 7 if (!isset($_REQUEST["file"])) {
 8     return;
 9 }
10 $file = $_FILES["file"];
11 if ($file["error"] > 0 ) {
12     echo "Error:".$_FILES["file"]["error"]."<br/>";
13 } else {        
14     $dir = "upload";    
15     if (!file_exists($dir)) {
16         mkdir($dir);
17     }    
18     if (file_exists("$dir/" . $file["name"])) {
19         echo "<h1>".$file["name"] . " already exists .</h1>";
20     } else {
21         move_uploaded_file($file["tmp_name"], "$dir/".$file["name"]);
22         echo "<h1>upload success !</h1> <br/> stored in " . "$dir/" . $file["name"];
23     }
24 }
25 ?>