PHP編寫登錄驗證碼功能 附調用方法

本文實例為大家分享了一個PHP寫的登錄驗證碼功能，供大家參考，具體內容如下

 ShowKey.php

<?php
session_start();
//設置COOKIE或Session
function esetcookie($name,$str,$life=0){
//本函數將字符串 str 全部變小寫字符串使驗證碼輸入不區分大小寫----在提交表單進行session比較同樣需要次函數轉化
 $_SESSION[$name]=strtolower($str);
}

//獲取隨機字符 此函數區分字符大小寫 如果不區分大小寫可加入函數strtolower
function domake_password($len) 
{ 
  $chars = array( 
    /*"a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", 
    "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", 
    "w", "x", "y", "z", "A", "B", "C", "D", "E", "F", "G", 
    "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", 
    "S", "T", "U", "V", "W", "X", "Y", "Z",*/ "0", "1", "2", 
    "3", "4", "5", "6", "7", "8", "9" 
  ); 
  $charsLen = count($chars) - 1; 
  shuffle($chars);// 將數組打亂
  $output = ""; 
  for ($i=0; $i<$len; $i++) 
  { 
    $output .= $chars[mt_rand(0, $charsLen)]; //獲得一個數組元素
  } 
  return $output;
} 

//顯示驗證碼
function ShowKey(){
 $key=domake_password(4);//獲取隨機值
 $set=esetcookie("checkkey",$key);//將隨機值寫入cookie或session
 //是否支持gd庫
 if(function_exists("imagejpeg")) 
 {
  header ("Content-type: image/jpeg");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干擾象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagejpeg($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagepng"))
 {
  header ("Content-type: image/png");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干擾象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagepng($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagegif")) 
 {
  header("Content-type: image/gif");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干擾象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagegif($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagewbmp")) 
 {
  header ("Content-type: image/vnd.wap.wbmp");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干擾象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagewbmp($img);
  imagedestroy($img);
 }
 else
 {
  //不支持驗證碼
  header("content-type:image/jpeg\r\n");
  header("Pragma:no-cache\r\n");
  header("Cache-Control:no-cache\r\n");
  header("Expires:0\r\n");
  $fp = fopen("data/vdcode.jpg","r"); 
 }
}
ShowKey();
?>

調用方法:

復制代碼 代碼如下:<img src="ShowKey.php" name="KeyImg" id="KeyImg"  onClick="KeyImg.src='ShowKey.php?'+Math.random()"> 

以上就是本文的全部內容，希望對大家學習php程序設計有所幫助。