web2.0的到来，ajax逐渐成为主流，什么是ajax，ajax的开发模式，优点，使用技术。（ajax概述，ajax使用的技术，需要注意的 问题，在PHP应用ajax技术的应用）
什么是ajax，ajax的开发模式，优点。
ajax是由jesse james garrett创建的，是asynchronous javascript and xml，异步javascript和xml技术，ajax并不是一门新的语言或技术，它是javascript，xml，css，dom等多种技术的组合，可以实现客户端的异步请求操作，可以在不刷新页面下与服务器进行通信，从而减少了用户的等待时间。
ajax开发模式：
浏览器（客户端） http传输，http请求， web服务器 数据存储，后端处理，继承系统，服务器端。
客户端（浏览器）JavaScript调用，ajax引擎 http请求，http传输， web和xml服务器，数据存储，后端处理，继承系统（服务端）。
优点：减轻服务器的负担，可以把部分由服务器负担的工作转移到客户端上，无刷新更新页面，可以调用xml等外部数据，基于标准化的并被广泛支持的技术。
JavaScript是一种在web页面中添加动态脚本代码的解释性程序语言。
xmlhttprequest
ie浏览器把xmlhttp
var http_request = new ActiveXObject("Msxml2.XMLHTTP");var http_request = new ActiveXObject("Microsoft.XMLHTTP");mozailla,safari等其他浏览器
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对象的常用方法：
open()方法用于设置进行异步请求目标的url
open("method", "url" [,asyncFlag [,"userName" [, "password"]]])send()方法用于向服务器发送请求
send(content)setRequestHeader()方法
setRequestHeader()方法为请求的http头设置值
setRequestHeader("label","value")label用于指定http头，value用于指定http头设置值
open()方法过后才能使用setRequestHeader()方法abort()方法
abort()方法用于停止当前异步请求
getAllResponseHeaders()方法
getAllResponseHeaders()方法用于以字符串形式完整的http头信息。
xmlhttpRequest对象常用的属性
onreadystatechange 每个状态改变时都会触发这个事件处理器，通常会调用一个JavaScript函数。
readyState 请求的状态：
0 为未初始化
1 为正在下载
2 为已加载
3 在交互中
4 为完成responseText 服务器的响应，表示字符串
responseXML 服务器的响应，表示xml
status 返回服务器的http状态码
statusText 返回http状态码对应的文本
xml语言为可扩展的标记语言，提供了用于描述结构化数据的格式。xmlHttpRequest对象与服务器交换的数据，通常采用xml格式。
dom为文档对象模型，为xml文档的解析定义了一组接口。
在PHP中应用AJAX技术检测用户名
<script language="javascript">
var http_request = false;
function createRequest(url) {
//初始化对象并发出XMLHttpRequest请求
http_request = false;
if (window.XMLHttpRequest) { //Mozilla等其他浏览器
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
http_request.overrideMimeType("text/xml");
}
} else if (window.ActiveXObject) { //IE浏览器
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
if (!http_request) {
alert("不能创建XMLHTTP实例!");
return false;
}
http_request.onreadystatechange = alertContents; //指定响应方法
http_request.open("GET", url, true); //发出HTTP请求
http_request.send(null);
}
function alertContents() { //处理服务器返回的信息
if (http_request.readyState == 4) {
if (http_request.status == 200) {
alert(http_request.responseText);
} else {
alert('您请求的页面发现错误');
}
}
}
</script>
<script language="javascript">
function checkName() {
var username = form1.username.value;
if(username=="") {
window.alert("请填写用户名!");
form1.username.focus();
return false;
}
else {
createRequest('checkname.php?username='+username+'&nocache='+new Date().getTime());
}
}
</script><?php
header('Content-type: text/html;charset=GB2312'); //指定发送数据的编码格式为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对要提交的中文进行编码
mysql_query("set names gb2312");
$username=$_GET[username];
$sql=mysql_query("select * from tb_user where name='".$username."'");
$info=mysql_fetch_array($sql);
if ($info){
echo "很报歉!用户名[".$username."]已经被注册!";
}else{
echo "祝贺您!用户名[".$username."]没有被注册!";
}
?>类别添加
<script language="javascript">
var http_request = false;
function createRequest(url) {
//初始化对象并发出XMLHttpRequest请求
http_request = false;
if (window.XMLHttpRequest) { //Mozilla等其他浏览器
http_request = new XMLHttpRequest();
if (http_request.overrideMimeType) {
http_request.overrideMimeType("text/xml");
}
} else if (window.ActiveXObject) { //IE浏览器
try {
http_request = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
http_request = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {}
}
}
if (!http_request) {
alert("不能创建XMLHTTP实例!");
return false;
}
http_request.onreadystatechange = alertContents; //指定响应方法
http_request.open("GET", url, true); //发出HTTP请求
http_request.send(null);
}
function alertContents() { //处理服务器返回的信息
if (http_request.readyState == 4) {
if (http_request.status == 200) {
sort_id.innerHTML=http_request.responseText; //设置sort_id HTML文本替换的元素内容
} else {
alert('您请求的页面发现错误');
}
}
}
</script>
<script language="javascript">
function checksort() {
var txt_sort = form1.txt_sort.value;
if(txt_sort=="") {
window.alert("请填写文章类别!");
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对要提交的中文进行编码
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'); //指定发送数据的编码格式为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对要提交的中文进行编码
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'); //指定发送数据的编码格式为GB2312
?>
<option value="<?php echo $result->sort;?>" selected><?php echo $result->sort;?></option>
<?php
}while($result=mysql_fetch_object($sql));
?>
</select>xml基础技术
了解xml，使用simpleXML解析文档的方法
遍历xml文档，修改，保存xml，创建xml文档的方法
xml语法
xml文档结构，xml声明，处理指令，注解，xml元素，xml属性，使用cdata标记，xml命令空间。
XML文档结构
<?xml version="1.0" encoding="gb2312" standalone="yes"?><?xml-stylesheet type="text/css" href="111.css"?>XML声明
<?xml version="1.0" encoding="gb2312" standalone="yes"?>
处理指令
<?xml-stylesheet type = "text/css" href="111.css"?><?处理指令名 处理执行信息?>xml-stylesheet：样式表单处理指令
type="text/css"：设定了文档所使用的样式是css
href="111.css"：设定了样式文件的地址
XML属性
<标签 属性名="属性值" 属性名=""…>内容</标签＞
SimpleXML
创建SimpleXML对象
Simplexml_load_file()函数，将指定的文件解析到内存中
Simplexml_load_string()函数，将创建的字符串解析到内存当中
Simplexml_load_date()函数，将一个使用dom函数创建的domDocument对象导入到内存当中
遍历所有子元素
children()方法和foreach循环语句可以遍历所有子节点元素
遍历所有属性
SimpleXML对象中的attributes()方法
<?xml version="1.0" encoding="GB2312"?>
<exam>
</exam><?php
header('Content-Type:text/html;charset=utf-8');
?>
<?php
/* 第一种方法 */
$xml_1 = simplexml_load_file("5.xml");
print_r($xml_1);
/* 第二种方法 */
$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);
/* 第三种方法 */
$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类，继承PHP5的DomDocument类
class Message_XML extends DomDocument{
//属性
private $Root;
//方法
//构造函数
public function __construct() {
parent:: __construct();
//创建或读取存储留言信息的XML文档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){ //添加数据
$Root = $this->documentElement;
//获取留言消息
$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);
//加入到根结点下
$Root->appendChild($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){ //删除数据
$Root = $this->documentElement;
$xpath = new DOMXPath($this);
$Node_Record= $xpath->query("//record[admin_id='$admin_id']");
$Root->removeChild($Node_Record->item(0));
$this->save("message.xml");
echo "<script>alert('删除成功');location.href='".$_SERVER['PHP_SELF']."'</script>";
}
public function show_message(){ //读取数据
$root=$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>用户名</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]'>删除</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'> 用户名：</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='添加数据'></td><td align='right'><a href=?Action=show_message>查看数据</a> </td></tr></form></table>";
}
}
?>
<html>
<head>
<title>定义一个PHP读取XML类</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>添加数据</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": //删除
$HawkXML->delete_message($_GET['admin_id']);
break;
}
?>
</table>
</body>
</html> <?php
//Message_XML类，继承PHP5的DomDocument类
class Message_XML extends DomDocument{
//属性
private $Root;
//方法
//构造函数
public function __construct() {
parent:: __construct();
//创建或读取存储留言信息的XML文档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){ //添加数据
$Root = $this->documentElement;
//获取留言消息
$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);
//加入到根结点下
$Root->appendChild($Node_Record);
$this->save("message.xml");
echo "<script>alert('添加成功');location.href='".$_SERVER['PHP_SELF']."'</script>";
}
public function show_message(){ //读取数据
$root=$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>用户名</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'> 用户名：</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='添加数据'></td><td align='right'><a href=?Action=show_message>查看数据</a> </td></tr></form></table>";
}
}
?>
<html>
<head>
<title>使用XML来存储少量的数据</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>添加数据</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>