Detailed explanation of PHP return data formatting class

<?php
/** 返回數據格式化類
*	Date:	2011-08-15
*	Author:	fdipzone
*/
class DataReturn{	// class start
	private $type;
	private $xmlroot;
	private $callback;
	private $returnData;

	public function __construct($param=array()){
		$this->type = $this->exists($param,&#39;type&#39;)? strtoupper($param[&#39;type&#39;]) : &#39;JSON&#39;;		// 類型 JSON,XML,CALLBACK,ARRAY
		$this->xmlroot = $this->exists($param,&#39;xmlroot&#39;)? $param[&#39;xmlroot&#39;] : &#39;xmlroot&#39;;		// xml root dom name
		$this->callback = $this->exists($param,&#39;callback&#39;)? $param[&#39;callback&#39;] : &#39;&#39;;			// JS callback function name
		$format = array();
		$format[&#39;retcode&#39;] = $this->exists($param,&#39;format.retcode&#39;)? $param[&#39;format&#39;][&#39;retcode&#39;] : &#39;retcode&#39;;//retcode 對應名稱
		$format[&#39;msg&#39;] = $this->exists($param,&#39;format.msg&#39;)? $param[&#39;format&#39;][&#39;msg&#39;] : &#39;msg&#39;;                //msg 對應名稱
		$format[&#39;data&#39;] = $this->exists($param,&#39;format.data&#39;)? $param[&#39;format&#39;][&#39;data&#39;] : &#39;data&#39;;            //data 對應名稱
		$result = array();
		$result[$format[&#39;retcode&#39;]] = $this->exists($param,&#39;retcode&#39;)? $param[&#39;retcode&#39;] : 0;
		$result[$format[&#39;msg&#39;]] = $this->exists($param,&#39;msg&#39;)? $param[&#39;msg&#39;] : &#39;&#39;;
		$result[$format[&#39;data&#39;]] = $this->exists($param,&#39;data&#39;)? $param[&#39;data&#39;] : &#39;&#39;;
		$this->returnData = $result;
	}
	//輸出數據
	public function data_return(){
		ob_clean();
		switch($this->type){
			case &#39;JSON&#39;:
				$this->json_return();
				break;
			case &#39;XML&#39;:
				$this->xml_return();
				break;
			case &#39;CALLBACK&#39;:
				$this->callback_return();
				break;
			case &#39;ARRAY&#39;:
				$this->array_return();
				break;
			default:
				$this->json_return();
		}
		exit();
	}
	//輸出JSON格式數據,如有callback參數則返回JSONP格式
	private function json_return(){
		header(&#39;content-type:text/html;charset=utf-8&#39;);
		if(empty($this->callback)){
			echo json_encode($this->returnData);
		}else{
			echo $this->callback.&#39;(&#39;.json_encode($this->returnData).&#39;);&#39;;
		}
	}
	//輸出XML格式數據
	private function xml_return(){
		header(&#39;content-type:text/xml;charset=utf-8&#39;);
		echo $this->xml_encode($this->returnData,$this->xmlroot);
	}
	//輸出JSON格式數據，并調用callback方法
	private function callback_return(){
		header(&#39;content-type:text/html;charset=utf-8&#39;);
		$this->callback = empty($this->callback)? &#39;callback&#39; : $this->callback;
		echo "<script type=\"text/javascript\">\r\n";
		echo $this->callback."(".json_encode($this->returnData).");\r\n";
		echo "</script>";
	}
	//輸出數組格式數據
	private function array_return(){
		header(&#39;content-type:text/html;charset=utf-8&#39;);
		echo &#39;<pre class="brush:php;toolbar:false">&#39;;
		print_r($this->returnData);
		echo &#39;

<?
    require_once(&#39;DataReturn.class.php&#39;);
    $param = array( // DataReturn 參數
                    &#39;type&#39;    => &#39;JSON&#39;, // 輸出的類型 JSON,XML,CALLBACK,ARRAY 默認為 JSON
                    &#39;retcode&#39; => &#39;1000&#39;, // retcode 的值，默認為0
                    &#39;msg&#39;     => &#39;&#39;,     // msg 的值，默認為空
                    &#39;data&#39;    => array(  // 要輸出的數據
                                    &#39;id&#39;     => &#39;100&#39;,
                                    &#39;name&#39;   => &#39;fdipzone&#39;,
                                    &#39;gender&#39; => 1,
                                    &#39;age&#39;    => 28
                                 ),
                    &#39;format&#39;  => array(// 輸出的數據key格式,默認為 retcode,msg,data
                                    &#39;retcode&#39; => &#39;status&#39;,
                                    &#39;msg&#39;     => &#39;info&#39;,
                                    &#39;data&#39;    => &#39;result&#39;
                                 ),
                    &#39;xmlroot&#39;  => &#39;xmlroot&#39;,  // 當type=XML時,XML根節點名稱，默認為xmlroot
                    &#39;callback&#39; => &#39;callback&#39;  /* 回調方法名稱
                                                   type=JSON時，默認為空，如不為空，則輸出callback({data});
                                                   type=CALLBACK時,默認為callback，自動調用頁面JS回調方法
                                              */
    );
    $obj = new DataReturn($param);  // 創建DataReturn類對象
    $obj->data_return();            // 按格式輸出數據
?>