分享下$_GET，$_POST，$_REQUEST和$_SERVER的用法，以及parse_str的用法。
首先，学习下$_GET、$_POST的用法。
$_GET变量获取通过get方式提交过来的数据。
$_POST 变量获取通过post方式提交过来的数据。
注意：使用的键名都是表单的name属性的值。

例如：
 

$_REQUEST的官方说明：
$_REQUEST — HTTP Request 变量默认情况下包含了 $_GET，$_POST 和 $_COOKIE 的数组。
在不关心是get过来的还是post，总之要取得某一个键的值，就用$_REQUEST即可。
不过$_REQUEST速度会比$_GET，$_POST稍慢点。
通过$_SERVER获取服务器端信息
$_SERVER是一个数组，包含了headers, paths, script locations等多种信息。早期的php版本使用$HTTP_server_VARS数组，现在已经弃用了。
不同的服务器$_SERVER的信息也不一定相同的。通常的用法如下：
 

比较常用的获取QUERY_STRING的方法，通过$_SERVER['QUERY_STRING']得到的是诸如name=mike&age=30这样的。要把这种格式的值转成变量，PHP中有个方法parse_str，可以实现这个功能。
官方的示例：
 

在本地环境通过代码：
 

用带格式的数据打印出数组内容：
 

php实现的操作session与cookie的类，可以对session、cookie进行加密与解密。

代码：

<?php 
/**
* session与cookie操作类
* by www.
*/
class Session 
{ 
    private $use_cookie; 
    private $preStr; 
    private $maxCookie; 
    private $cookieLenght; 
    private $stringone; 
    private $duratacookie; 
    private $secret; 

    public function __construct ($cook = "zipcook") { 

        $this->use_cookie = $cook;    //choose mode 
        $this->preStr= "_KK_";        //prefix for cookies 
        $this->maxCookie=20;        //since cookie lenght is limited, I've limited the number of cookies 
        $this->cookieLenght=3096;    //max cookie length (it depends on browser) 
        $this->duratacookie=3600*24;//cookie life time 
        $this->secred="secret";        //secret keyword to crypt/decrypt, change this to customize encryption 
        if ($this->use_cookie=="yes") { 
        } elseif ($this->use_cookie=="zipcook") { 
            $this->stringone = $this->prelevaStringaTotale(); 
        } else { 
            ini_set("session.gc_maxlifetime","432000"); 
            ini_set("url_rewriter.tags",""); 
            ini_set("session.use_trans_sid", false); 
            session_start(); 
        } 
    } 

    /* --------------------------- */ 
    /* parse_str 变量             */ 
    /* -------------------------- */ 
    private function build_str($ar) { 
        $qs = array(); 
        foreach ($ar as $k => $v) { $qs[] = $k.'='.$v; } 
        return join('&', $qs); 
    } 

    /* ------------------------------ */ 
    /* 获取加密后的cookie列表  */ 
    /* cookies                       */ 
    /* ----------------------------- */ 
    private function prelevaStringaTotale() { 
        $cookiesSet = array_keys($_COOKIE); 
        $out = ""; 
        for ($x=0;$x<count($cookiesSet);$x++) { 
            if (strpos(" ".$cookiesSet[$x],$this->preStr)==1) 
                $out.=$_COOKIE[$cookiesSet[$x]]; 
        } 
        return $this->decrypta($out); 
    } 

    public function debug() { 
        // for debug 
        return $this->prelevaStringaTotale(); 
    } 

    /* ---------------------------- */ 
    /* 确定可用的cookies            */ 
    /* ---------------------------- */ 
    private function calcolaCookieLiberi() { 
        $cookiesSet = array_keys($_COOKIE); 
        $c=0; 
        for ($x=0;$x<count($cookiesSet);$x++) { 
            if (strpos(" ".$cookiesSet[$x],$this->preStr)==1) 
                $c+=1; 
        } 
        return $this->maxCookie - count($cookiesSet) + $c; 
    } 

    /* ------------------------ */ 
    /* 分割字符串存储进cookie   */ 
    /* ------------------------ */ 
    private function my_str_split($s,$len) { 
        $output = array(); 
        if (strlen($s)<=$len) { 
            $output[0] = $s; 
            return $output; 
        } 
        $i = 0; 
        while (strlen($s)>0) { 
            $s = substr($s,0,$len); 
            $output[$i]=$s; 
            $s = substr($s,$len); 
            $i++; 
        } 
        return $output; 
    } 

    /* ----------------------------- */ 
    /* 保存session与cookie值         */ 
    /* ----------------------------- */ 
    public function register($var,$value) { 
        $this->set($var,$value); 
    } 
    public function set($var,$value) { 
        if ($this->use_cookie=="yes") { 
            setcookie($var,$this->crypta($value),time()+$this->duratacookie,"/", $_SERVER['HTTP_HOST'] ); 
        } elseif ($this->use_cookie=="zipcook") { 
            if ($this->stringone!="") { 
                parse_str($this->stringone, $vars); 
            } else { 
                $vars=array(); 
            } 
            $vars[$var] = $value;    //aggiungo-modifico valore 
            $str = $this->crypta($this->build_str($vars)); 
            $arr = $this->my_str_split($str,$this->cookieLenght); 
            $cLiberi = $this->calcolaCookieLiberi(); 
            if (count($arr) < $cLiberi) { 
                // c'ho spazio, posso registrare 
                $this->stringone = $this->build_str($vars); 
                for ($i=0;$i<count($arr);$i++) { 
                    setcookie($this->preStr.$i,$arr[$i],time()+$this->duratacookie,"/", $_SERVER['HTTP_HOST'] ); 
                } 
            } else { 
                //cookie overflow 
                return "errore cookie overflow"; 
            } 
        } else { 
            session_register($var); 
        } 
    } 

    /* ------------------------------------------- */ 
    /* 获取加密后的cookie值，未加密，请直接取得  */ 
    /* ------------------------------------------- */ 
    public function get($var) { 
        if ($this->use_cookie=="yes") { 
            global $_COOKIE; 
            return $this->decrypta($_COOKIE[$var]); 
        } elseif ($this->use_cookie=="zipcook") { 
            if ($this->stringone!="") { 
                parse_str($this->stringone, $vars); 
            } else { 
                return ""; 
            } 
            if(!isset($vars[$var])) { 
                return ""; 
            } 
            return $vars[$var]; 
        } else { 
            if ($this->is_registered($var)) { 
                $this->$var=$GLOBALS[$var]; 
            } 
            else 
                if(isset($GLOBALS[$var])) 
                    $this->$var = $GLOBALS[$var]; 
                else 
                        $this->$var=""; 
            return($this->$var); 
        } 
    } 

    /* --------------------------- */ 
    /* 清空session或cookie        */ 
    /* -------------------------- */ 
    public function finish() { 
        if ($this->use_cookie=="yes") { 
            $cookiesSet = array_keys($_COOKIE); 
            for ($x=0;$x<count($cookiesSet);$x++) { 
                //echo $cookiesSet[$x]."<br/>"; 
                setcookie($cookiesSet[$x],"",time()-3600*24,"/", $_SERVER['HTTP_HOST'] );    //faccio scadere il cookie 
            } 

        } elseif ($this->use_cookie=="zipcook") { 
            $cookiesSet = array_keys($_COOKIE); 
            for ($x=0;$x<count($cookiesSet);$x++) { 
                if (strpos(" ".$cookiesSet[$x],$this->preStr)==1) 
                    setcookie($cookiesSet[$x],"",time()-3600*24,"/",$_SERVER['HTTP_HOST']); 
                $this->stringone=""; 
            } 
        } else { 
            session_destroy(); 
            $_SESSION = array(); 
        } 
    } 

    /* 加密 */ 
    private function crypta($t){ 
        if ($t=="") return $t; 
        $r = md5(10); $c=0; $v=""; 
        for ($i=0;$i<strlen($t);$i++){ 
            if ($c==strlen($r)) $c=0; 
            $v.= substr($r,$c,1) . (substr($t,$i,1) ^ substr($r,$c,1)); 
            $c++; 
        } 
        return (base64_encode($this->ed($v))); 
    } 
    /* 解密 */ 
    private function decrypta($t) { 
        if ($t=="") return $t; 
        $t = $this->ed(base64_decode(($t))); 
        $v = ""; 
        for ($i=0;$i<strlen($t);$i++){ 
            $md5 = substr($t,$i,1); 
            $i++; 
            $v.= (substr($t,$i,1) ^ $md5); 
        } 
        return $v; 
    } 

    /* used to crypt/decrypt */ 
    private function ed($t) { 
        $r = md5($this->secret); $c=0; $v=""; 
        for ($i=0;$i<strlen($t);$i++) { 
            if ($c==strlen($r)) $c=0; 
            $v.= substr($t,$i,1) ^ substr($r,$c,1); 
            $c++; 
        } 
        return $v; 
    } 


} 
?>

分享两个实例，学习这个类的用法。
例1：

<? 
//test1.php 
include("session.class.php"); 
$s = new Session(); 
$s->set("userid","27"); 
?>

例2：

<? 
//test2.php 
include("session.class.php"); 
$s = new Session(); 
echo $s->get("userid"); //27 
?>

使用phpexcel类库，实现导出数据，代码如下：

<?php
/**
* phpexcel实例 导出数据
* by www.
*/
public function export_data($data = array())
    {
        # code...
        include_once(APP_PATH.'Tools/PHPExcel/Classes/PHPExcel/Writer/IWriter.php') ;
        include_once(APP_PATH.'Tools/PHPExcel/Classes/PHPExcel/Writer/Excel5.php') ;
        include_once(APP_PATH.'Tools/PHPExcel/Classes/PHPExcel.php') ;
        include_once(APP_PATH.'Tools/PHPExcel/Classes/PHPExcel/IOFactory.php') ;
        $obj_phpexcel = new PHPExcel();
        $obj_phpexcel->getActiveSheet()->setCellValue('a1','Key');
        $obj_phpexcel->getActiveSheet()->setCellValue('b1','Value');        
        if($data){
            $i =2;
            foreach ($data as $key => $value) {
                # code...
                $obj_phpexcel->getActiveSheet()->setCellValue('a'.$i,$value);
                $i++;
            }
        }    

        $obj_Writer = PHPExcel_IOFactory::createWriter($obj_phpexcel,'Excel5');
        $filename = "outexcel.xls";

        header("Content-Type: application/force-download"); 
        header("Content-Type: application/octet-stream"); 
        header("Content-Type: application/download"); 
        header('Content-Disposition:inline;filename="'.$filename.'"'); 
        header("Content-Transfer-Encoding: binary"); 
        header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); 
        header("Cache-Control: must-revalidate, post-check=0, pre-check=0"); 
        header("Pragma: no-cache"); 
        $obj_Writer->save('php://output'); 
    } //at 2013-8-24 11:22:18

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