PHP实现登录验证码功能及调用方法实例教程

以上为效果图。

实现流程：
1.新加一个ShowKey.php文件，这里是验证码显示的文件，具体怎么写的自己可以研究一下，这个是别人写的，拿来用就可以了，自己写的也不一定好。

<?php

session_start();

//设置COOKIE或Session

function esetcookie($name,$str,$life=0){

//本函数将字符串 str 全部变小写字符串使验证码输入不区分大小写----在提交表单进行session比较同样需要次函数转化

 $_SESSION[$name]=strtolower($str);

}

 

//获取随机字符 此函数区分字符大小写 如果不区分大小写可加入函数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);// 将数组打乱

  $output = ""; 

  for ($i=0; $i<$len; $i++) 

  { 

    $output .= $chars[mt_rand(0, $charsLen)]; //获得一个数组元素

  } 

  return $output;

} 

 

//显示验证码

function ShowKey(){

 $key=domake_password(4);//获取随机值

 $set=esetcookie("checkkey",$key);//将随机值写入cookie或session

 //是否支持gd库

 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++) //加入干扰象素

  {

   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++) //加入干扰象素

  {

   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++) //加入干扰象素

  {

   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++) //加入干扰象素

  {

   imagesetpixel($img,rand()%70,rand()%30,$black);

  }

  imagewbmp($img);

  imagedestroy($img);

 }

 else

 {

  //不支持验证码

  header("content-type:image/jpegrn");

  header("Pragma:no-cachern");

  header("Cache-Control:no-cachern");

  header("Expires:0rn");

  $fp = fopen("data/vdcode.jpg","r"); 

 }

}

ShowKey();

?>

2.前台页面调用：注意input里面的name值，这个值要传递到检查登录的文件中。

	  	  <div class="form-group">
				    <label class="col-sm-2 control-label">验证码：</label>
				    <div class="col-sm-10">
				      <input type="text" name="imgId" class="form-control" placeholder="验证码"><img src="ShowKey.php" name="KeyImg" id="KeyImg"  onClick="KeyImg.src='ShowKey.php?'+Math.random()">
				    </div>
				  </div>

3.session_start();这个必须要加到顶部，不然是验证不过的。

<?php
session_start();  //必须的，很多都是因为这个一个验证不通过
header("Content-type:text/html;charset=utf-8");
//接收表单的数据
  
$username = $_POST['username'];
$password = $_POST['password'];

$imgId_req = $_REQUEST['imgId']; //接受表单传递的数据
//验证该字符串是否注册了session变量 
if($_SESSION['checkkey']==$imgId_req){
	
	echo "<script>alert('验证通过');
	window.location.href='login.php';</script>";
}
else{
	
	 echo "<script>alert('验证不通过');
	window.location.href='login.php';</script>";
}