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PHP实现GIF图片验证码的步骤

来源：爱站网时间：2019-12-04编辑：网友分享
验证码是一种区分用户的全自动程序，它可以有效防止黑客残忍地破解特定程序，下面就由爱站技术频道小编来PHP实现GIF图片验证码的步骤，对这热门行业感兴趣的你千万不要错过喔。
验证码是一种区分用户的全自动程序，它可以有效防止黑客残忍地破解特定程序，下面就由爱站技术频道小编来PHP实现GIF图片验证码的步骤，对这热门行业感兴趣的你千万不要错过喔。
第一步：创建ImageCode.php.html" target="_blank">php文件，验证码生成函数代码如下：
<?php
/**
 * ImageCode 生成GIF图片验证
 * @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
    {
      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 = rand(0,1);
      $todrawline = 1;
      if($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 .= "!\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); 
  } 
}

第二步：验证码生成，创建yzimg.php，并引用入文件ImageCode.php。代码如下：

<?php
if(!isset($_SESSION)){
  session_start();
}
require_once(dirname(__FILE__)."ImageCode.php");
unset($_SESSION['yzm']);
$randCode = '';
$chars = 'abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPRSTUVWXYZ23456789';
for ( $i = 0; $i < 4; $i++ )
{
  $randCode .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
}
$_SESSION['yzm']=$randCode;     // 记录session
ImageCode($randCode, 60);
 
/*方法二*/
/*$authstr = mt_rand(1000, 9999);  // 生成随机字符串
$_SESSION['yzm'] = $authstr;  // 记录session
ImageCode($authstr, 60);  // 显示GIF动画*/
?>

 第三步：调用和显示验证码，在需要添加验证码的页面加入以下代码，代码如下：

<input name="yzm" type="text" class="input1" size="12" style="width:70px;"/>
         <SCRIPT LANGUAGE="JavaScript">
<!--
document.write('<img id="yz_Img" name="imageField" class="yz_Img" title="刷新验证码" onclick="this.src=this.src+Math.random();" src="yzimg.php?'+Math.random()+'">');
//-->
</SCRIPT>

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