web2.0的到來，ajax逐漸成為主流，什么是ajax，ajax的開發模式，優點，使用技術。（ajax概述，ajax使用的技術，需要注意的 問題，在PHP應用ajax技術的應用）
什么是ajax，ajax的開發模式，優點。
ajax是由jesse james garrett創建的，是asynchronous javascript and xml，異步javascript和xml技術，ajax並不是一門新的語言或技術，它是javascript，xml，css，dom等多種技術的組合，可以實現客戶端的異步請求操作，可以在不刷新頁面下與服務器進行通信，從而減少了用戶的等待時間。
ajax開發模式：
瀏覽器（客戶端） http傳輸，http請求， web服務器 數據存儲，后端處理，繼承系統，服務器端。
客戶端（瀏覽器）JavaScript調用，ajax引擎 http請求，http傳輸， web和xml服務器，數據存儲，后端處理，繼承系統（服務端）。
優點：減輕服務器的負擔，可以把部分由服務器負擔的工作轉移到客戶端上，無刷新更新頁面，可以調用xml等外部數據，基於標准化的並被廣泛支持的技術。
JavaScript是一種在web頁面中添加動態腳本代碼的解釋性程序語言。
xmlhttprequest
ie瀏覽器把xmlhttp
var http_request = new ActiveXObject("Msxml2.XMLHTTP");var http_request = new ActiveXObject("Microsoft.XMLHTTP");mozailla,safari等其他瀏覽器
var http_request = new XMLHttpRequest();if(window.XMLHttpRequest){ http_request = new XMLHttpRequest(); }else if(window.ActiveXObject){ try{ http_request = new ActiveXObject("Msxml2.XMLHTTP"); }catch(e){ try{ http_request = new ActiveXObject("Msxml2.XMLHTTP"); }catch(e){ try{ http_request = new ActiveXObject("Microsoft.XMLHTTP"); }catch(e){} } }XMLHttpRequest對象的常用方法：
open()方法用於設置進行異步請求目標的url
open("method", "url" [,asyncFlag [,"userName" [, "password"]]])send()方法用於向服務器發送請求
send(content)setRequestHeader()方法
setRequestHeader()方法為請求的http頭設置值
setRequestHeader("label","value")label用於指定http頭，value用於指定http頭設置值
open()方法過后才能使用setRequestHeader()方法abort()方法
abort()方法用於停止當前異步請求
getAllResponseHeaders()方法
getAllResponseHeaders()方法用於以字符串形式完整的http頭信息。
xmlhttpRequest對象常用的屬性
onreadystatechange 每個狀態改變時都會觸發這個事件處理器，通常會調用一個JavaScript函數。
readyState 請求的狀態：
0 為未初始化 1 為正在下載 2 為已加載 3 在交互中 4 為完成responseText 服務器的響應，表示字符串
responseXML 服務器的響應，表示xml
status 返回服務器的http狀態碼
statusText 返回http狀態碼對應的文本
xml語言為可擴展的標記語言，提供了用於描述結構化數據的格式。xmlHttpRequest對象與服務器交換的數據，通常采用xml格式。
dom為文檔對象模型，為xml文檔的解析定義了一組接口。
在PHP中應用AJAX技術檢測用戶名
<script language="javascript"> var http_request = false; function createRequest(url) { //初始化對象並發出XMLHttpRequest請求 http_request = false; if (window.XMLHttpRequest) { //Mozilla等其他瀏覽器 http_request = new XMLHttpRequest(); if (http_request.overrideMimeType) { http_request.overrideMimeType("text/xml"); } } else if (window.ActiveXObject) { //IE瀏覽器 try { http_request = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { http_request = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {} } } if (!http_request) { alert("不能創建XMLHTTP實例!"); return false; } http_request.onreadystatechange = alertContents; //指定響應方法 http_request.open("GET", url, true); //發出HTTP請求 http_request.send(null); } function alertContents() { //處理服務器返回的信息 if (http_request.readyState == 4) { if (http_request.status == 200) { alert(http_request.responseText); } else { alert('您請求的頁面發現錯誤'); } } } </script> <script language="javascript"> function checkName() { var username = form1.username.value; if(username=="") { window.alert("請填寫用戶名!"); form1.username.focus(); return false; } else { createRequest('checkname.php?username='+username+'&nocache='+new Date().getTime()); } } </script><?php header('Content-type: text/html;charset=GB2312'); //指定發送數據的編碼格式為GB2312 $link=mysql_connect("localhost","root","root"); mysql_select_db("db_database",$link); $GB2312string=iconv( 'UTF-8', 'gb2312//IGNORE' , $RequestAjaxString); //Ajax中先用encodeURIComponent對要提交的中文進行編碼 mysql_query("set names gb2312"); $username=$_GET[username]; $sql=mysql_query("select * from tb_user where name='".$username."'"); $info=mysql_fetch_array($sql); if ($info){ echo "很報歉!用戶名[".$username."]已經被注冊!"; }else{ echo "祝賀您!用戶名[".$username."]沒有被注冊!"; } ?>類別添加
<script language="javascript"> var http_request = false; function createRequest(url) { //初始化對象並發出XMLHttpRequest請求 http_request = false; if (window.XMLHttpRequest) { //Mozilla等其他瀏覽器 http_request = new XMLHttpRequest(); if (http_request.overrideMimeType) { http_request.overrideMimeType("text/xml"); } } else if (window.ActiveXObject) { //IE瀏覽器 try { http_request = new ActiveXObject("Msxml2.XMLHTTP"); } catch (e) { try { http_request = new ActiveXObject("Microsoft.XMLHTTP"); } catch (e) {} } } if (!http_request) { alert("不能創建XMLHTTP實例!"); return false; } http_request.onreadystatechange = alertContents; //指定響應方法 http_request.open("GET", url, true); //發出HTTP請求 http_request.send(null); } function alertContents() { //處理服務器返回的信息 if (http_request.readyState == 4) { if (http_request.status == 200) { sort_id.innerHTML=http_request.responseText; //設置sort_id HTML文本替換的元素內容 } else { alert('您請求的頁面發現錯誤'); } } } </script> <script language="javascript"> function checksort() { var txt_sort = form1.txt_sort.value; if(txt_sort=="") { window.alert("請填寫文章類別!"); form1.txt_sort.focus(); return false; } else { createRequest('checksort.php?txt_sort='+txt_sort); } } </script><?php $link=mysql_connect("localhost","root","root"); mysql_select_db("db_database",$link); $GB2312string=iconv( 'UTF-8', 'gb2312//IGNORE',$RequestAjaxString); //Ajax中先用encodeURIComponent對要提交的中文進行編碼 mysql_query("set names gb2312"); $sort=$_GET[txt_sort]; mysql_query("insert into tb_sort(sort) values('$sort')"); header('Content-type: text/html;charset=GB2312'); //指定發送數據的編碼格式為GB2312 ?> <table border="0" cellpadding="0" cellspacing="0"> <tr> <td> <select name="select" > <?php $link=mysql_connect("localhost","root","root"); mysql_select_db("db_database23",$link); $GB2312string=iconv( 'UTF-8', 'gb2312//IGNORE' , $RequestAjaxString); //Ajax中先用encodeURIComponent對要提交的中文進行編碼 mysql_query("set names gb2312"); $sql=mysql_query("select distinct * from tb_sort group by sort"); $result=mysql_fetch_object($sql); do{ header('Content-type: text/html;charset=GB2312'); //指定發送數據的編碼格式為GB2312 ?> <option value="<?php echo $result->sort;?>" selected><?php echo $result->sort;?></option> <?php }while($result=mysql_fetch_object($sql)); ?> </select>xml基礎技術
了解xml，使用simpleXML解析文檔的方法
遍歷xml文檔，修改，保存xml，創建xml文檔的方法
xml語法
xml文檔結構，xml聲明，處理指令，注解，xml元素，xml屬性，使用cdata標記，xml命令空間。
XML文檔結構
<?xml version="1.0" encoding="gb2312" standalone="yes"?><?xml-stylesheet type="text/css" href="111.css"?>XML聲明
<?xml version="1.0" encoding="gb2312" standalone="yes"?>
處理指令
<?xml-stylesheet type = "text/css" href="111.css"?><?處理指令名 處理執行信息?>xml-stylesheet：樣式表單處理指令
type="text/css"：設定了文檔所使用的樣式是css
href="111.css"：設定了樣式文件的地址
XML屬性
<標簽 屬性名="屬性值" 屬性名=""…>內容</標簽＞
SimpleXML
創建SimpleXML對象
Simplexml_load_file()函數，將指定的文件解析到內存中
Simplexml_load_string()函數，將創建的字符串解析到內存當中
Simplexml_load_date()函數，將一個使用dom函數創建的domDocument對象導入到內存當中
遍歷所有子元素
children()方法和foreach循環語句可以遍歷所有子節點元素
遍歷所有屬性
SimpleXML對象中的attributes()方法
<?xml version="1.0" encoding="GB2312"?> <exam> </exam><?php header('Content-Type:text/html;charset=utf-8'); ?> <?php /* 第一種方法 */ $xml_1 = simplexml_load_file("5.xml"); print_r($xml_1); /* 第二種方法 */ $str = <<<XML <?xml version='1.0' encoding='gb2312'?> <Object> <ComputerBook> <title>PHP</title> </ComputerBook> </Object> XML; $xml_2 = simplexml_load_string($str); echo '<br>'; print_r($xml_2); /* 第三種方法 */ $dom = new domDocument(); $dom -> loadXML($str); $xml_3 = simplexml_import_dom($dom); echo '<br>'; print_r($xml_3); ?><?php header('Content-Type:text/html;charset=utf-8'); ?> <style type="text/css"> <?php $str = <<<XML <?xml version='1.0' encoding='gb2312'?> <object> <book> <computerbook>PHP</computerbook> </book> <book> <computerbook>PHP</computerbook> </book> </object> XML; $xml = simplexml_load_string($str); foreach($xml->children() as $layer_one){ print_r($layer_one); echo '<br>'; foreach($layer_one->children() as $layer_two){ print_r($layer_two); echo '<br>'; } } ?>
<?php $str = <<<XML <?xml version='1.0' encoding='gb2312'?> <object name='commodity'> <book type='computerbook'> <bookname name='22'/> </book> <book type='historybook'> <booknanme name='111'/> </book> </object> XML; $xml = simplexml_load_string($str); foreach($xml->children() as $layer_one){ foreach($layer_one->attributes() as $name => $vl){ echo $name.'::'.$vl; } echo '<br>'; foreach($layer_one->children() as $layer_two){ foreach($layer_two->attributes() as $nm => $vl){ echo $nm."::".$vl; } echo '<br>'; } } ?><?php header('Content-Type:text/html;charset=utf-8'); ?> <?php $str = <<<XML <?xml version='1.0' encoding='gb2312'?> <object name='商品'> <book> <computerbook>P123</computerbook> </book> <book> <computerbook name='456'/> </book> </object> XML; $xml = simplexml_load_string($str); echo $xml[name].'<br>'; echo $xml->book[0]->computerbook.'<br>'; echo $xml->book[1]->computerbook['name'].'<br>'; ?><?php header('Content-Type:text/html;charset=utf-8'); $str=<<<XML <?xml version='1.0' encoding='gb2312'?> <object name='商品'> <book> <computerbook type='12356'>123</computerbook> </book> </object> XML; $xml = simplexml_load_string($str); echo $xml[name].'<br />'; $xml->book->computerbook['type'] = iconv('gb2312','utf-8','PHP123'); $xml->book->computerbook = iconv('gb2312','utf-8','PHP456'); echo $xml->book->computerbook['type'].' => '; echo $xml->book->computerbook; ?><?php $xml = simplexml_load_file('10.xml'); $xml->book->computerbook['type'] = iconv('gb2312','utf-8','PHP1'); $xml->book->computerbook = iconv('gb2312','utf-8','PHP2'); $modi = $xml->asXML(); file_put_contents('10.xml',$modi); $str = file_get_contents('10.xml'); echo $str; ?><?php //Message_XML類，繼承PHP5的DomDocument類 class Message_XML extends DomDocument{ //屬性 private $Root; //方法 //構造函數 public function __construct() { parent:: __construct(); //創建或讀取存儲留言信息的XML文檔message.xml if (!file_exists("message.xml")){ $xmlstr = "<?xml version='1.0' encoding='GB2312'?><message></message>"; $this->loadXML($xmlstr); $this->save("message.xml"); } else $this->load("message.xml"); } public function add_message($user,$address){ //添加數據 $Root = $this->documentElement; //獲取留言消息 $admin_id =date("Ynjhis"); $Node_admin_id= $this->createElement("admin_id"); $text= $this->createTextNode(iconv("GB2312","UTF-8",$admin_id)); $Node_admin_id->appendChild($text); $Node_user = $this->createElement("user"); $text = $this->createTextNode(iconv("GB2312","UTF-8",$user)); $Node_user->appendChild($text); $Node_address = $this->createElement("address"); $text= $this->createTextNode(iconv("GB2312","UTF-8",$address)); $Node_address->appendChild($text); $Node_Record = $this->createElement("record"); $Node_Record->appendChild($Node_admin_id); $Node_Record->appendChild($Node_user); $Node_Record->appendChild($Node_address); //加入到根結點下 $Root->appendChild($Node_Record); $this->save("message.xml"); echo "<script>alert('添加成功');location.href='".$_SERVER['PHP_SELF']."'</script>"; } public function delete_message($admin_id){ //刪除數據 $Root = $this->documentElement; $xpath = new DOMXPath($this); $Node_Record= $xpath->query("//record[admin_id='$admin_id']"); $Root->removeChild($Node_Record->item(0)); $this->save("message.xml"); echo "<script>alert('刪除成功');location.href='".$_SERVER['PHP_SELF']."'</script>"; } public function show_message(){ //讀取數據 $root=$this-documentElement; $xpath=new DOMXPath($this); $Node_Record=$this->getElementsByTagName("record"); $Node_Record_length=$Node_Record->length; print"<table width='506' bgcolor='#FFFFCC'><tr>"; print"<td width='106' height='22' align='center'>"; print"<b>用戶名</b>"; print"</td><td width='400' align='center'>"; print"<b>留言信息</b></td></tr>"; for($i=0;$i<$Node_Record->length;$i++){ $k=0; foreach($Node_Record->item($i)->childNodes as $articles){ $field[$k]=iconv("UTF-8","GB2312",$articles->textContent); $k++; } print"<table width='506' bgcolor='#FFFFCC'><tr>"; print"<td width='100' height='22' align='center'>"; print"$field[1]"; print"</td><td width='300' align='left'>"; print"$field[2]"; print"</td><td width='100' align='center'>"; print"<a href='?Action=delete_message&admin_id=$field[0]'>刪除</a></td>"; print"</tr></table>"; }} public function post_message(){ print "<table width='506' bgcolor='#FFFFCC'><form method='post' action='?Action=add_message'>"; print "<tr><td width='106'height='22'> 用戶名：</td><td><input type=text name='user' size=50></td></tr>"; print "<tr><td width='106' height='22'> 留言信息：</td><td width='400'><textarea name='address' cols='48' rows='5' id='address'></textarea></td></tr>"; print "<tr><td width='106' height='30'> <input type='submit' value='添加數據'></td><td align='right'><a href=?Action=show_message>查看數據</a> </td></tr></form></table>"; } } ?> <html> <head> <title>定義一個PHP讀取XML類</title> <style> td,body{font-size:12px} a:link { text-decoration: none; } a:visited { text-decoration: none; } a:hover { text-decoration: none; } a:active { text-decoration: none; } </style> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"></head> <body> <table width=506 height=50 border=0 cellpadding=0 cellspacing=0 bgcolor="#33BE6B"> <tr> <td width="506" height=50 valign="bottom" background="title.gif"><table width="506"> <tr> <td height="24" align="right" scope="col"> <a href=?Action=post_message>添加數據</a> </td> </tr> </table></td> </tr> <?php $HawkXML = new Message_XML; $Action =""; if(isset($_GET['Action'])) $Action = $_GET['Action']; switch($Action){ case "show_message": //查看 $HawkXML->show_message(); break; case "post_message": //提交 $HawkXML->post_message(); break; case "add_message": //添加 $HawkXML->add_message($_POST['user'],$_POST['address']); break; case "delete_message": //刪除 $HawkXML->delete_message($_GET['admin_id']); break; } ?> </table> </body> </html> <?php //Message_XML類，繼承PHP5的DomDocument類 class Message_XML extends DomDocument{ //屬性 private $Root; //方法 //構造函數 public function __construct() { parent:: __construct(); //創建或讀取存儲留言信息的XML文檔message.xml if (!file_exists("message.xml")){ $xmlstr = "<?xml version='1.0' encoding='GB2312'?><message></message>"; $this->loadXML($xmlstr); $this->save("message.xml"); } else $this->load("message.xml"); } public function add_message($user,$address){ //添加數據 $Root = $this->documentElement; //獲取留言消息 $admin_id =date("Ynjhis"); $Node_admin_id= $this->createElement("admin_id"); $text= $this->createTextNode(iconv("GB2312","UTF-8",$admin_id)); $Node_admin_id->appendChild($text); $Node_user = $this->createElement("user"); $text = $this->createTextNode(iconv("GB2312","UTF-8",$user)); $Node_user->appendChild($text); $Node_address = $this->createElement("address"); $text= $this->createTextNode(iconv("GB2312","UTF-8",$address)); $Node_address->appendChild($text); $Node_Record = $this->createElement("record"); $Node_Record->appendChild($Node_admin_id); $Node_Record->appendChild($Node_user); $Node_Record->appendChild($Node_address); //加入到根結點下 $Root->appendChild($Node_Record); $this->save("message.xml"); echo "<script>alert('添加成功');location.href='".$_SERVER['PHP_SELF']."'</script>"; } public function show_message(){ //讀取數據 $root=$this-documentElement; $xpath=new DOMXPath($this); $Node_Record=$this->getElementsByTagName("record"); $Node_Record_length=$Node_Record->length; print"<table width='506' bgcolor='#FFFFCC'><tr>"; print"<td width='106' height='22' align='center'>"; print"<b>用戶名</b>"; print"</td><td width='400' align='center'>"; print"<b>留言信息</b></td></tr>"; for($i=0;$i<$Node_Record->length;$i++){ $k=0; foreach($Node_Record->item($i)->childNodes as $articles){ $field[$k]=iconv("UTF-8","GB2312",$articles->textContent); $k++; } print"<table width='506' bgcolor='#FFFFCC'><tr>"; print"<td width='100' height='22' align='center'>"; print"$field[1]"; print"</td><td width='400' align='left'>"; print"$field[2]"; print"</td>"; print"</tr></table>"; }} public function post_message(){ print "<table width='506' bgcolor='#FFFFCC'><form method='post' action='?Action=add_message'>"; print "<tr><td width='106'height='22'> 用戶名：</td><td><input type=text name='user' size=50></td></tr>"; print "<tr><td width='106' height='22'> 留言信息：</td><td width='400'><textarea name='address' cols='48' rows='5' id='address'></textarea></td></tr>"; print "<tr><td width='106' height='30'> <input type='submit' value='添加數據'></td><td align='right'><a href=?Action=show_message>查看數據</a> </td></tr></form></table>"; } } ?> <html> <head> <title>使用XML來存儲少量的數據</title> <style> td,body{font-size:12px} a:link { text-decoration: none; } a:visited { text-decoration: none; } a:hover { text-decoration: none; } a:active { text-decoration: none; } </style> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"></head> <body> <table width=506 height=50 border=0 cellpadding=0 cellspacing=0 bgcolor="#33BE6B"> <tr> <td width="506" height=50 valign="bottom" background="title.gif"><table width="506"> <tr> <td height="24" align="right" scope="col"> <a href=?Action=post_message>添加數據</a> </td> </tr> </table></td> </tr> <?php $HawkXML = new Message_XML; $Action =""; if(isset($_GET['Action'])) $Action = $_GET['Action']; switch($Action){ case "show_message": //查看 $HawkXML->show_message(); break; case "post_message": //提交 $HawkXML->post_message(); break; case "add_message": //添加 $HawkXML->add_message($_POST['user'],$_POST['address']); break; } ?> </table> </body> </html>