PHP单例模式定义与使用实例详解

classDB{

   private$_link;

   //   保持单例类的静态变量

   static$_instance;

   //   私有的构造函数

   privatefunction__construct(){

       $this->_link = @mysqli_connect(__HOST__, __USER__, __PASSWORD__, __DATABASE__);

       if(! ($this->_link)){

          echo'Something wrong occurs on the database connection!' 

       }

   }

   //   防止单例类被克隆

   privatefunction__clone(){}

   //   外界访问单例类实例的接口

   publicstaticfunctiongetInstance(){

       if(! (self::$_instanceinstanceofself)){

          self::$_instance=newself();

       }

       returnself::$_instance;

   }

}

classDB {

   /**

    * the database connection

    * @var   resource

    * @access private

    */

   private$_link;

   /**

    * the static instance of single db

    * @var   object

    * @access static

    */

   static$_instance;

   /**

    * construct the single object

    * @return null

    * @access private

    */

   privatefunction__construct(){

       $this->_link = @mysqli_connect(__HOST__, __USER__, __PASSWORD__, __DATABASE__);

       if(! ($this->_link)){

          echo'Something wrong occurs on the database connection!' 

       }

   }

   /**

    * empty clone

    * @return null

    * @access private

    */

   privatefunction__clone(){}

   /**

    * for other object to get the instance of db

    * @return self::instance

    * @access public

    */

   publicstaticfunctiongetInstance(){

       if(! (self::$_instanceinstanceofself)){

          self::$_instance=newself();

       }

       returnself::$_instance;

   }

   /**

    * query

    * @param  sql string

    * @param  message string

    * @return   resource

    * @access public

    */

   publicfunctionquery($sql,$message){

       $result= @mysqli_query($this->$_link,$sql)ordie($message. mysqli_error($this->$_link));

       return$result;

   }

   /**

    * mysqli_num_rows

    * @param  result resource

    * @return   int

    * @access public

    */

   publicfunctionnum($result){

       return@mysqli_num_rows($result);

   }

   /**

    * mysqli_fetch_array

    * @param  result resource

    * @return   array

    * @access public

    */

   publicfunctionfetchArr($result){

       return@mysqli_fetch_array($result);

   }

   /**

    * mysqli_insert_id

    * @return   int

    * @access public

    */

   publicfunctionlast_id(){

       return@mysqli_insert_id($this->_link);  

   }

   /**

    * close the database connection

    * @param  result resource

    * @return   null

    * @access public

    */

   publicfunctionclose(){

       @mysqli_close($this->_link);

   }

   /**

    * fetch once result from the specific sql query

    * @param  sql string

    * @param  message string

    * @return   array

    * @access public

    */

   publicfunctionfetchArrOnce($sql,$message){

       $result=$this->query($sql,$message);

       $row=$this->fetchArr($result);

       return$row;

   }

   /**

    * fetch all results from the specific sql query

    * @param  sql string

    * @param  message string

    * @return   array

    * @access public

    */

   publicfunctionfetchArrMore($sql,$message){

       $result=$this->query($sql,$message);

       $moreRow=array();

       while($row=$this->fetchArr($result)){

          $moreRow[] =$row;

       }

       return$moreRow;

   }

   /**

    * fetch the number of results from the specific sql query

    * @param  sql string

    * @param  message string

    * @return   array

    * @access public

    */

   publicfunctionfetchNum($sql,$message){

       $result=$this->query($sql,$message);

       $resultNum=$this->num($result);

       return$resultNum;

   }

   /**

    * mysqli_prepare

    * @param  sql string

    * @return   stmt object

    * @access public

    */

   publicfunctionprepare($sql){

       return@mysqli_prepare($this->_link,$sql);

   }

   /**

    * mysqli_stmt_execute

    * @param  stmt object

    * @param  message string

    * @return   bool

    * @access public

    */

   publicfunctionstmt_execute($stmt,$message){

       @mysqli_stmt_execute($stmt)ordie($message. mysqli_error($this->_link));

   }

}

define("__HOST__","localhost");

define("__USER__","root");

define("__PASSWORD__","");

define("__DATABASE__","eee");

$db= DB::getInstance();

<?php

/**

 * 取得给定日期所在周的开始日期和结束日期

 * @param string $gdate 日期，默认为当天，格式：YYYY-MM-DD

 * @param int $weekStart 一周以星期一还是星期天开始，0为星期天，1为星期一

 * @return array 数组array( "开始日期 ",  "结束日期");

 */

functiongetAWeekTimeSlot($gdate='',$weekStart= 0) {

 if(!$gdate){

 $gdate=date("Y-m-d");

 }

 $w=date("w",strtotime($gdate) );//取得一周的第几天,星期天开始0-6

 $dn=$w?$w-$weekStart: 6;//要减去的天数

 $st=date("Y-m-d",strtotime("$gdate  - ".$dn."  days ") );

 $en=date("Y-m-d",strtotime("$st  +6  days ") );

 returnarray($st,$en);//返回开始和结束日期

}

$timeSlot=getAWeekTimeSlot('2017-01-24',1);

echo"Week Start:{$timeSlot[0]}--->Week End: {$timeSlot[1]} ";

?>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<metacontent="text/html; charset=UTF-8"http-equiv="Content-Type">

<title>标题：{title}</title>

</head>

<body>

<b>此新闻的内容：</b>{content}

</body>

</html>

<?php

  //实际应用中很可能是查询数据库取内容。

  $rows=array(array("替换标题1","替换内容1"),array("替换标题2","替换内容2"));

  $filename="tmp.htm";

  foreach($rowsas$id=>$val){

    $title=$val[0];

    $content=$val[1];

    $pagename="测试".$id.".html";

    //对文件名的编码，避免中文文件名乱码

    $pagename= iconv("UTF-8","GBK",$pagename);

    //读取模板

    $tmpfile=fopen($filename,"r");

    $string=fread($tmpfile,filesize($filename));

    $string=str_replace("{title}",$title,$string);

    $string=str_replace("{content}",$content,$string);

    fclose($tmpfile);

    //写新文件

    $newpage=fopen($pagename,"w");

    fwrite($newpage,$string);

    fclose($newpage);

  }

  echo"创建成功！";

?>