1.验证码图片生成
captcha.php
//1.生成100*30大小的图片,默认为黑色 $image = imagecreatetruecolor(100,30); //创建白色底图 $bgcolor = imagecolorallocate($image,255,255,255); //用白色填充黑色 imagefill ($image,0,0,$bgcolor); //2.随机显示数字或字母 $captch_code = ""; for($i=0;$i<4;$i++){ $fontsize=6; $fontcolor=imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120)); $data = "abcdefghijkmnpqrstuvwxy3456789"; $fontcontent =substr($data,rand(0,strlen($data)),1); $captch_code .=$fontcontent; $x = ($i*100/4)+rand(5,10); $y = rand(5,10); imagestring($image, $fontsize, $x, $y, $fontcontent,$fontcolor); } $_SESSION["authcode"] = $captch_code; //3.增加干扰 //干扰点 for($i=0;$i<100;$i++){ $pointcolor=imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200)); imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor); } //干扰线 for($i=0;$i<2;$i++){ $linecolor=imagecolorallocate($image,rand(80,220),rand(80,220),rand(80,220)); imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor); } header("content-type:image/png"); imagepng($image);
2.页面实现验证码功能
form.php
<?php if(isset($_POST["authcode"])){ session_start(); if(strtolower($_POST["authcode"])==$_SESSION["authcode"]){ echo "OK"; }else{ echo "NO"; } } ?> <!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <form action="form.php" method="post"> <p>验证码图片: <img id="img" border="1" src="captcha.php?r=<?php echo rand()?>" alt=""> <a href="javascript:void(0)" onclick="document.getElementById('img').src='captcha.php?r'+Math.random() ">换一个</a> </p> <p><input type="text" name="authcode"></p> <p><input type="submit" value="提交"></p> </form> </body> </html>