本文实例讲述了php对文件进行hash运算的方法。分享给大家供大家参考。具体如下：
这段代码非常有用，如果你下载了一个文件，网站提供了hash结果，你可以对你下载下来的文件进行hash运算，以验证下载的文件是否正确。
<html><head> <title>Hash (Check) Files</title> <style type="text/css"> #ok{color:green;} #nono{color:red;} </style></head><body> <?php if(!empty($_FILES)){ if ($_FILES["file"]["error"] > 0){ switch($_FILES["file"]["error"]){ case 1: echo "<b id="nono">Error: The uploaded file exceeds the upload_max_filesize directive in php.ini</b><br>"; break; case 2: echo "<b id="nono">Error: The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form.</b><br>"; break; case 3: echo "<b id="nono">Error: The uploaded file was only partially uploaded.</b><br>"; break; case 4: echo "<b id="nono">Error: No file was uploaded.</b><br>"; break; case 6: echo "<b id="nono">Error: Missing a temporary folder.</b><br>"; break; case 7: echo "<b id="nono">Error: Failed to write file to disk.</b><br>"; break; case 8: echo "<b id="nono">Error: A PHP extension stopped the file upload.</b><br>"; break; default: echo "<b id="nono">Unknown error occured.</b><br>"; } } else { echo "Upload: " . $_FILES["file"]["name"] . "<br>"; echo "Type: " . $_FILES["file"]["type"] . "<br>"; echo "Size: " . (round($_FILES["file"]["size"] / 1024, 2)) . " Kb<br><br>"; if(array_search($_POST["algo"], hash_algos())===false){ echo "Unknown hashing algorithm requested.<br>"; } else { echo "Hashing Algorithm: ". $_POST["algo"] . "<br>"; $hash = hash_file($_POST["algo"], $_FILES["file"]["tmp_name"]); echo "Calculated hash: " . $hash . "<br>"; if($_POST["exphash"]!=="none" && !empty($_POST["exphash"])){ echo "Expected hash: " . $_POST["exphash"] . "<br><br>"; echo ($hash==$_POST["exphash"])? "<b id="ok">Hash matched expected value.</b>" : "<b id="nono">Hash did not match expected value.</b>"; echo "<br>"; } } } ?> <br> <button onClick="document.location.reload(true)">Again</button> <?php } else { ?> <form action="" method="post" enctype="multipart/form-data"> <input type="hidden" name="exphash" value="none"> <label for="file">Filename:</label> <input type="file" name="file" id="file"> <input type="submit" name="submit" value="Submit" /><br> <label>Expected hash(optional): <input type="text" name="exphash" size="100"></label> <br><br>Choose an algorithm (This is the list of all the available algorithms in your php installation)<br> <?php foreach(hash_algos() as $algo){ if($algo=="md5"){ echo "<label><input type="radio" name="algo" value="$algo" checked="checked">$algo</label><br>"; } else { echo "<label><input type="radio" name="algo" value="$algo">$algo</label><br>"; } } ?> </form> <?php } ?></body></html>希望本文所述对大家的php程序设计有所帮助。
