ubuntu:通过封装验证码类库一步步安装php的gd扩展

我相信很多人的lamp环境都是直接复制一堆参数安装进去的，这里有可能成功，也有可能失败，如果是新手，估计要碰到各种错误，就算安装成功，也未必知道那些参数是干嘛的，反正装进去能用就行。

我当初开始的时候也是这样， 完全一脸懵逼，直到我后来进修了( C语言，Linux，Linux系统编程，计算机原理等 )才能玩转服务器配置，理解原理。

本文通过一个经典的验证码功能，告诉你如何按需安装扩展!!!

要封装一个php的验证码类库，那么需要gd扩展的支持，由于我之前的php是精简编译安装的，没有gd库的支持，所以要先安装php的gd库

要想成功安装gd库，需要安装很多的依赖: zlib, png, jpeg, libiconv, freetype

1，zlib我之前在安装 php memcache的扩展时候，已经安装过了

2，安装png

wget http://prdownloads.sourceforge.net/libpng/libpng-1.5.4.tar.gz?download

mv libpng-1.5.4.tar.gz\?download libpng-1.5.4.tar.gz

tar xf libpng-1.5.4.tar.gz

cd libpng-1.5.4/

./configure

make && sudo make install

3，安装jpeg

wget http://www.ijg.org/files/jpegsrc.v9b.tar.gz

tar xf jpegsrc.v9b.tar.gz

cd jpeg-9b/

./configure

make && sudo make install

4，安装libiconv

wget https://ftp.gnu.org/pub/gnu/libiconv/libiconv-1.15.tar.gz

tar xf libiconv-1.15.tar.gz

cd libiconv-1.15/

./configure

make && sudo make install

5，安装freeType

wget https://download.savannah.gnu.org/releases/freetype/freetype-2.9.tar.gz

tar xf freetype-2.9.tar.gz

cd freetype-2.9/

./configure

make && sudo make install

6，到了最关键的地方了，安装php gd扩展 

切换到php原码包下  ext/gd  这个目录

>先执行phpize外挂模块( /usr/local/php54/bin/phpize  )

>./configure --with-php-config=/usr/local/php54/bin/php-config -with-png-dir --with-freetype-dir --with-jpeg-dir -with-zlib-dir --with-gd

>make && sudo make install

开始封装php验证码库，最后效果

 <?php

 class Captcha {
     //验证码字符个数
     protected $num;
     //宽度
     protected $width;
     //高度
     protected $height;
     //资源
     protected $im;
     //类型: 1:纯数字, 2:纯字母 3:数字与字母混合
     protected $codeType;
     //生成的验证码字符串
     protected $codeString;

     public function __construct( $_num = 4, $_width = 150, $_height = 50, $_codeType = 3 ){
         $this->num = $_num;
         $this->width = $_width;
         $this->height = $_height;
         $this->codeType = $_codeType;
         $this->codeString = $this->createCodeString();
     }

     public function __get( $name ) {
         if( $name == 'codeString' ) {
             return $this->codeString;
         }
         return false;
     }

     protected function createCodeString(){
         switch( $this->codeType ){
             case 1:
                 $code = $this->createNumCode();
                 break;
             case 2:
                 $code = $this->createCharCode();
                 break;
             case 3:
                 $code = $this->createNumCharCode();
                 break;
             default:
                 die( "暂时没有其他的验证码类型,你可以继承这个类来添加额" );
         }
         return $code;
     }

     protected function createNumCode(){
         $numString = join( "", range( 0, 9 ) );
         return substr( str_shuffle( $numString ), 0, $this->num );
     }

     protected function createCharCode(){
         $charString = join( "", range( 'a', 'z' ) );
         $charString .= strtoupper( $charString );
         return substr( str_shuffle( $numString ), 0, $this->num );
     }

     protected function createNumCharCode(){
         $numCharString = join( "", range( 0, 9 ) );
         $charString = join( "", range( 'a', 'z' ) );
         $charString .= strtoupper( $charString );
         $mixedString = $numCharString . $charString;
         return substr( str_shuffle( $mixedString ), 0, $this->num );
     }

     protected function createCanvas(){
         $this->im = imagecreatetruecolor( $this->width, $this->height );
     }

     protected function fillCanvas( $type ){
         switch( $type ) {
             case 1:
                 $color = imagecolorallocate( $this->im, mt_rand( 0, 150 ), mt_rand( 0, 150 ), mt_rand( 0, 150 ) );
                 break;
             case 2:
                 $color = imagecolorallocate( $this->im, mt_rand( 150, 255 ), mt_rand( 150, 255 ), mt_rand( 150, 255 ) );
                 break;
             default:
                 die( "不支持的填充类型" );
                 break;
         }
         imagefill( $this->im, 0, 0, $color );
     }

     protected function drawCodeString(){
         for( $i = 0; $i < $this->num; $i++ ){
             $fontColor = imagecolorallocate( $this->im, mt_rand( 0, 255 ), mt_rand( 0, 255 ), mt_rand( 0, 255 ) );
             $char = $this->codeString[$i];
             $x = ( $i * ( ($this->width) / $this->num ) ) + mt_rand( 5, 10 );
             $y = mt_rand( 0, $this->height / 2 ) + mt_rand( 5, 10 );
             imagestring( $this->im, 5, $x, $y, $char, $fontColor );
         }
     }

     protected function renderImage(){
         header( "Content-type:image/png" );
         imagepng( $this->im );
     }

     protected function fillDisturb(){
             for( $i = 0; $i < 100; $i++ ){
                 $color = imagecolorallocate( $this->im, mt_rand( 0, 255 ), mt_rand( 0, 255 ), mt_rand( 0, 255 ) );
                 imagesetpixel( $this->im, mt_rand( 0, $this->width ), mt_rand( 0, $this->height ), $color );
             }
     }

     public function render(){
         //创建画布/背景
         $this->createCanvas();
         //填充画布颜色
         $this->fillCanvas( 1 );
         //填充干扰元素
         $this->fillDisturb();
         //填充验证码
         $this->drawCodeString();
         //显示验证码
         $this->renderImage();
     }
 }

 $capt = new Captcha();
 //echo $capt->codeString . PHP_EOL;
 $capt->render();
 ?>

小结：

1，复习类库的封装

2，理解扩展安装原理