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"; var $VER="GIFEncoder V2.06"; 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); $this->GIF.="!\377\13NETSCAPE2.0\3\1".GIFEncoder::GIFWord($this->LOP)."\0"; } } 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))); $Locals_ext="!\xF9\x04".chr(($this->DIS<<2)+0).chr(($d>>0)&0xFF).chr(($d>>8)&0xFF)."\x0\x0"; 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){ $Locals_ext="!\xF9\x04".chr(($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：

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。