php代码，主要把RGB改成随机生成，不是之前固定的七种颜色了：
1 <?php 2 // ob_clean(); 3 header("content-type:image/png"); 4 $width = 110; 5 $height = 40; 6 $img = imagecreatetruecolor($width, $height); 7 $string = "hello"; 8 //7种颜色，存入数组 9 $red = imagecolorallocate($img, 255, 0, 0); 10 $white = imagecolorallocate($img, 255, 255, 255); 11 $green = imagecolorallocate($img, 0, 255, 0); 12 $blue = imagecolorallocate($img, 0, 0, 255); 13 $aaa = imagecolorallocate($img, 255, 255, 0); 14 $bbb = imagecolorallocate($img, 0, 255, 255); 15 $ccc = imagecolorallocate($img, 255, 0, 255); 16 $colors = array($white,$red,$green,$blue,$aaa,$bbb,$ccc); 17 //颜色换成随机组成的RGB，每次循环都生成一次 18 $color = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255)); 19 //画点 20 for ($i=0; $i < 10; $i++) { 21 $color1 = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255)); 22 imagesetpixel($img, mt_rand(0,$width), mt_rand(0,$height), $color1); 23 } 24 //划线 25 for ($i=0; $i < 4; $i++) { 26 $color2 = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255)); 27 imageline($img, mt_rand(0,$width), mt_rand(0,$height), mt_rand(0,$width), mt_rand(0,$height), $color2); 28 } 29 //生成4位验证码 30 $a1 = range(0, 9); 31 $a2 = range(a, z); 32 $a3 = range(A, Z); 33 $a4 = array_merge($a1,$a2,$a3); 34 //改用shuffle打断顺序，array_slice取出前4个字母数字。不然如果用mt_rand在循环中每次取一个，还要生成字符串，不好比对 35 shuffle($a4); 36 $a5 = array_slice($a4,0,4); 37 $num = 4; 38 $fontsize = 20; 39 for ($i=0; $i < 4; $i++) { 40 $color3 = imagecolorallocate($img, rand(0,255), rand(0,255), rand(0,255)); 41 imagettftext($img, $fontsize, mt_rand(-30,30), $width/$num*$i+5, 30, $color3, "Fonts/msyh.ttf", $a5[$i]); 42 } 43 imagepng($img); 44 ?>
HTML代码（后缀也是php）：
1 <!doctype html> 2 <html lang="en"> 3 <head> 4 <meta charset="UTF-8"> 5 <title>注册</title> 6 </head> 7 <body> 8 <form action="test.php" method = "get"> 9 <table> 10 <tr> 11 <td>用户名:</td> 12 <td><input type="text"><br/></td> 13 </tr> 14 <tr> 15 <td>密码:</td> 16 <td><input type="text"><br/></td> 17 </tr> 18 <tr> 19 <td>验证码:</td> 20 <td><input type="text" name = "txtYanZheng"><br/></td> 21 </tr> 22 <tr> 23 <td></td> 24 <td><img src="yanzhengma.php" id = "yanzhengma" ></form></td> 25 </tr> 26 <tr> 27 <td><input type="submit" value="提交" ></td> 28 </tr> 29 </table> 30 <?php 31 $var = ' 32 <script type="text/javascript"> 33 onload = function(){ 34 var yanzhengma = document.getElementById("yanzhengma"); 35 yanzhengma.onclick = function(){ 36 this.src = "yanzhengma.php?"+Math.random(); 37 }; 38 } 39 </script> 40 '; 41 echo $var ?> 42 </body> 43 </html>