这是一个通过php生成的动态验证码图片的示例，重点是可以运行哦！下面先发下效果图：
下面是php生成动态验证码需要用到的相关类和函数。
<?php
/**
*imagecode 生成包含验证码的gif图片的函数
*@param $string 字符串
*@param $width 宽度
*@param $height 高度
**/
function imagecode($string='',$width=75,$height=25){
$authstr=$string?$string:((time()%2==0)?mt_rand(1000,9999):mt_rand(10000,99999));
$board_width=$width;
$board_height=$height;
// 生成一个32帧的gif动画
for($i=0;$i<32;$i++){
ob_start();
$image=imagecreate($board_width,$board_height);
imagecolorallocate($image,0,0,0);
// 设定文字颜色数组
$colorlist[]=imagecolorallocate($image,15,73,210);
$colorlist[]=imagecolorallocate($image,0,64,0);
$colorlist[]=imagecolorallocate($image,0,0,64);
$colorlist[]=imagecolorallocate($image,0,128,128);
$colorlist[]=imagecolorallocate($image,27,52,47);
$colorlist[]=imagecolorallocate($image,51,0,102);
$colorlist[]=imagecolorallocate($image,0,0,145);
$colorlist[]=imagecolorallocate($image,0,0,113);
$colorlist[]=imagecolorallocate($image,0,51,51);
$colorlist[]=imagecolorallocate($image,158,180,35);
$colorlist[]=imagecolorallocate($image,59,59,59);
$colorlist[]=imagecolorallocate($image,0,0,0);
$colorlist[]=imagecolorallocate($image,1,128,180);
$colorlist[]=imagecolorallocate($image,0,153,51);
$colorlist[]=imagecolorallocate($image,60,131,1);
$colorlist[]=imagecolorallocate($image,0,0,0);
$fontcolor=imagecolorallocate($image,0,0,0);
$gray=imagecolorallocate($image,245,245,245);
$color=imagecolorallocate($image,255,255,255);
$color2=imagecolorallocate($image,255,0,0);
imagefill($image,0,0,$gray);
$space=15;// 字符间距
if($i>0){// 屏蔽第一帧
$top=0;
for($k=0;$k<strlen($authstr);$k++){
$colorrandom=mt_rand(0,sizeof($colorlist)-1);
$float_top=rand(0,4);
$float_left=rand(0,3);
imagestring($image,6,$space*$k,$top+$float_top,substr($authstr,$k,1),$colorlist[$colorrandom]);
}
}
for($k=0;$k<20;$k++){
$colorrandom=mt_rand(0,sizeof($colorlist)-1);
imagesetpixel($image,rand()%70,rand()%15,$colorlist[$colorrandom]);
}
// 添加干扰线
for($k=0;$k<3;$k++){
$colorrandom=mt_rand(0,sizeof($colorlist)-1);
$todrawline=1;
if($todrawline){
imageline($image,mt_rand(0,$board_width),mt_rand(0,$board_height),mt_rand(0,$board_width),mt_rand(0,$board_height),$colorlist[$colorrandom]);
}else{
$w=mt_rand(0,$board_width);
$h=mt_rand(0,$board_width);
imagearc($image,$board_width-floor($w / 2),floor($h / 2),$w,$h, rand(90,180),rand(180,270),$colorlist[$colorrandom]);
}
}
imagegif($image);
imagedestroy($image);
$imagedata[]=ob_get_contents();
ob_clean();
++$i;
}
$gif=new gifencoder($imagedata);
header('content-type:image/gif');
echo $gif->getanimation();
}
/**
*gifencoder类
**/
class gifencoder{
var $gif="gif89a"; /* gif header 6 bytes */
var $ver="gifencoder v2.06"; /* encoder version */
var $buf=array();
var $lop=0;
var $dis=2;
var $col=-1;
var $img=-1;
var $err=array(
'err00'=>"does not supported function for only one image!",
'err01'=>"source is not a gif image!",
'err02'=>"unintelligible flag ",
'err03'=>"could not make animation from animated gif source",
);
function gifencoder($gif_src,$gif_dly=100,$gif_lop=0,$gif_dis=0, $gif_red=0,$gif_grn=0,$gif_blu=0,$gif_mod='bin'){
if(!is_array($gif_src)&&!is_array($gif_tim)){
printf("%s: %s",$this->ver,$this->err['err00']);
exit(0);
}
$this->lop=($gif_lop>-1)?$gif_lop:0;
$this->dis=($gif_dis>-1)?(($gif_dis<3)?$gif_dis:3):2;
$this->col=($gif_red>-1&&$gif_grn>-1&&$gif_blu>-1)?($gif_red |($gif_grn<<8)|($gif_blu<<16)):-1;
for($i=0,$src_count=count($gif_src);$i<$src_count;$i++){
if(strtolower($gif_mod)=="url"){
$this->buf[]=fread(fopen($gif_src [$i],"rb"),filesize($gif_src [$i]));
}elseif(strtolower($gif_mod)=="bin"){
$this->buf [ ]=$gif_src [ $i ];
}else{
printf("%s: %s(%s)!",$this->ver,$this->err [ 'err02' ],$gif_mod);
exit(0);
}
if(substr($this->buf[$i],0,6)!="gif87a"&&substr($this->buf [$i],0,6)!="gif89a"){
printf("%s: %d %s",$this->ver,$i,$this->err ['err01']);
exit(0);
}
for($j=(13+3*(2<<(ord($this->buf[$i]{10})&0x07))),$k=true;$k;$j++){
switch($this->buf [$i]{$j}){
case "!":
if((substr($this->buf[$i],($j+3),8))=="netscape"){
printf("%s: %s(%s source)!",$this->ver,$this->err ['err03'],($i+1));
exit(0);
}
break;
case ";":
$k=false;
break;
}
}
}
gifencoder::gifaddheader();
for($i=0,$count_buf=count($this->buf);$i<$count_buf;$i++){
gifencoder::gifaddframes($i,$gif_dly[$i]);
}
gifencoder::gifaddfooter();
}
function gifaddheader(){
$cmap=0;
if(ord($this->buf[0]{10})&0x80){
$cmap=3*(2<<(ord($this->buf [0]{10})&0x07));
$this->gif.=substr($this->buf [0],6,7);
$this->gif.=substr($this->buf [0],13,$cmap);
$this->gif.="!37713netscape2.031".gifencoder::gifword($this->lop)." ";
}
}
function gifaddframes($i,$d){
$locals_str=13+3*(2 <<(ord($this->buf[$i]{10})&0x07));
$locals_end=strlen($this->buf[$i])-$locals_str-1;
$locals_tmp=substr($this->buf[$i],$locals_str,$locals_end);
$global_len=2<<(ord($this->buf [0]{10})&0x07);
$locals_len=2<<(ord($this->buf[$i]{10})&0x07);
$global_rgb=substr($this->buf[0],13,3*(2<<(ord($this->buf[0]{10})&0x07)));
$locals_rgb=substr($this->buf[$i],13,3*(2<<(ord($this->buf[$i]{10})&0x07)));
$locals_ext="!xf9x04".chr(($this->dis<<2)+0).chr(($d>>0)&0xff).chr(($d>>8)&0xff)."x0x0";
if($this->col>-1&&ord($this->buf[$i]{10})&0x80){
for($j=0;$j<(2<<(ord($this->buf[$i]{10})&0x07));$j++){
if(ord($locals_rgb{3*$j+0})==($this->col>> 0)&0xff&&ord($locals_rgb{3*$j+1})==($this->col>> 8)&0xff&&ord($locals_rgb{3*$j+2})==($this->col>>16)&0xff){
$locals_ext="!xf9x04".chr(($this->dis<<2)+1).chr(($d>>0)&0xff).chr(($d>>8)&0xff).chr($j)."x0";
break;
}
}
}
switch($locals_tmp{0}){
case "!":
$locals_img=substr($locals_tmp,8,10);
$locals_tmp=substr($locals_tmp,18,strlen($locals_tmp)-18);
break;
case ",":
$locals_img=substr($locals_tmp,0,10);
$locals_tmp=substr($locals_tmp,10,strlen($locals_tmp)-10);
break;
}
if(ord($this->buf[$i]{10})&0x80&&$this->img>-1){
if($global_len==$locals_len){
if(gifencoder::gifblockcompare($global_rgb,$locals_rgb,$global_len)){
$this->gif.=($locals_ext.$locals_img.$locals_tmp);
}else{
$byte=ord($locals_img{9});
$byte|=0x80;
$byte&=0xf8;
$byte|=(ord($this->buf [0]{10})&0x07);
$locals_img{9}=chr($byte);
$this->gif.=($locals_ext.$locals_img.$locals_rgb.$locals_tmp);
}
}else{
$byte=ord($locals_img{9});
$byte|=0x80;
$byte&=0xf8;
$byte|=(ord($this->buf[$i]{10})&0x07);
$locals_img {9}=chr($byte);
$this->gif.=($locals_ext.$locals_img.$locals_rgb.$locals_tmp);
}
}else{
$this->gif.=($locals_ext.$locals_img.$locals_tmp);
}
$this->img=1;
}
function gifaddfooter(){
$this->gif.=";";
}
function gifblockcompare($globalblock,$localblock,$len){
for($i=0;$i<$len;$i++){
if($globalblock{3*$i+0}!=$localblock{3*$i+0}||$globalblock{3*$i+1}!=$localblock{3*$i+1}||$globalblock{3*$i+2}!=$localblock{3*$i+2}){
return(0);
}
}
return(1);
}
function gifword($int){
return(chr($int&0xff).chr(($int>>8)&0xff));
}
function getanimation(){
return($this->gif);
}
}
php生成动态验证码用法示例：
/*调用示例*/
session_start();
$checkcode='';
$chars='abcdefghjkmnpqrstuvwxyzabcdefghjklmnprstuvwxyz23456789';
for($i=0;$i<4;$i++){
$checkcode.=substr($chars,mt_rand(0,strlen($chars)-1),1);
}
$_session['code']=strtoupper($checkcode);// 记录session
imagecode($checkcode,60);// 显示gif动画
以上就是php如何生成动态验证码的实现方法，希望对大家的学习有所帮助。
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