php對文件進行hash運算的方法

更新時間：2015年04月03日 12:02:40 作者：不吃皮蛋

這篇文章主要介紹了php對文件進行hash運算的方法,涉及針對文件的hash運算技巧,非常具有實用價值,需要的朋友可以參考下

本文實例講述了php對文件進行hash運算的方法。分享給大家供大家參考。具體如下：

這段代碼非常有用，如果你下載了一個文件，網(wǎng)站提供了hash結果，你可以對你下載下來的文件進行hash運算，以驗證下載的文件是否正確。

<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: &nbsp;&nbsp;' . $_POST['exphash'] . '<br><br>';
      echo ($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>

希望本文所述對大家的php程序設計有所幫助。

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