php生成验证码图片

0:效果图

1:index.php用来生成验证码图片

 1 <?php
 2 session_start();
 3 header ('Content-Type: image/png');
 4 $image=imagecreatetruecolor(100, 30);
 5 //背景颜色为白色
 6 $color=imagecolorallocate($image, 255, 255, 255);
 7 imagefill($image, 20, 20, $color);
 8 // for($i=0;$i<4;$i++){
 9     // $font=6;
10     // $x=rand(5,10)+$i*100/4;
11     // $y=rand(8, 15);
12     // $string=rand(0, 9);
13     // $color=imagecolorallocate($image, rand(0,120), rand(0,120), rand(0,120));
14     // imagestring($image, $font, $x, $y, $string, $color);
15 // }
16 $code='';
17 for($i=0;$i<4;$i++){
18     $fontSize=8;
19     $x=rand(5,10)+$i*100/4;
20     $y=rand(5, 15);
21     $data='abcdefghijklmnopqrstuvwxyz123456789';
22     $string=substr($data,rand(0, strlen($data)),1);
23     $code.=$string;
24     $color=imagecolorallocate($image,rand(0,120), rand(0,120), rand(0,120));
25     imagestring($image, $fontSize, $x, $y, $string, $color);
26 }
27 $_SESSION['code']=$code;//存储在session里
28 for($i=0;$i<200;$i++){
29     $pointColor=imagecolorallocate($image, rand(100, 255), rand(100, 255), rand(100, 255));
30     imagesetpixel($image, rand(0, 100), rand(0, 30), $pointColor);
31 }
32 for($i=0;$i<2;$i++){
33     $linePoint=imagecolorallocate($image, rand(150, 255), rand(150, 255), rand(150, 255));
34     imageline($image, rand(10, 50), rand(10, 20), rand(80,90), rand(15, 25), $linePoint);
35 }
36 imagepng($image);
37 imagedestroy($image);
38 ?>

2:form.php前端页面.用于输入验证码并验证

 1 <?php
 2     if(isset($_REQUEST['code'])){
 3          session_start();
 4         if($_REQUEST['code']==$_SESSION['code']){
 5             echo "<font color='red'>输入正确</font>";
 6         }else{
 7             echo "<font color='red'>输入错误</font>";
 8         }
 9     }
10 ?>
11 <!DOCTYPE html>
12 <html>
13     <head>
14         <meta chartset="UTF-8" />
15         <style type="text/css" rel="stylesheet">
16             a{
17                 text-decoration:none;
18                 font-size:30px;
19                 color:blue;
20             }
21             a:hover{
22                 text-decoration:underline;
23             }
24         </style>
25     </head>
26     <body>
27         <form action="form.php" method="get">
28             验证码: &nbsp;<img id="img" src="index.php?" onclick="changeCode()"/>
29             <a href="javascript:void(0)" onclick="changeCode()">看不清?</a>&nbsp;<br />
30             请输入验证码:&nbsp;<input name="code" /><br />
31             <input type="submit" value="提交" />
32         </form>
33     </body>
34     <script type="text/javascript">
35         
36         function changeCode(){
37             var img=document.getElementById('img');
38             //img.src='index.php?r='+Math.random();
39             img.setAttribute('src','index.php?r='+Math.random());
40         }
41     </script>
42 </html>