这篇文章将为大家详细讲解有关php如何对文件进行hash运算，小编觉得挺实用的，因此分享给大家做个参考，希望大家阅读完这篇文章后可以有所收获。
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>
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