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($i=0;$i0){// 屏蔽第一帧 $top=0; for($k=0;$ksource is not a gif image!, 'err02'=>unintelligible flag , 'err03'=>could not make animation from animated gif source, ); function gifencoder($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)?(($gif_discol=($gif_red>-1&&$gif_grn>-1&&$gif_blu>-1)?($gif_red |($gif_grn<<8)|($gif_bluver,$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($j=(13+3*(2buf [$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);$ibuf[0]{10})&0x80){ $cmap=3*(2gif.=substr($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){ $locals_str=13+3*(2 buf[$i])-$locals_str-1; $locals_tmp=substr($this->buf[$i],$locals_str,$locals_end); $global_len=2>8)&0xff).\x0\x0; if($this->col>-1&&ord($this->buf[$i]{10})&0x80){ for($j=0;$j> 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->dis0)&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>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。