ajax的server部分(php版)

//向id為show的div顯示server端回應的正確
function display(message)
...{
showDIV=document.getElementById("show");
showDIV.innerHTML=message;
}
//向id為show的div顯示server端回應的錯誤訊息
function displayError(errormessage)
...{
//顯示出錯訊息
display("Error retrieving the new message!
"+errormessage);
}

///////////////////////////////////////////////// //////////
//2. event-driven函式(keyup函式)
////////////////////////////////////////////////// /////////
var keyupAddress="php/suggest.php?action=keyup&keyword=";
function keyup()
...{
if(xmlHttp)
...{
//server不忙的時候發送非同步請求
if(xmlHttp.readyState==0||xmlHttp.readyState==4)
...{
try
...{
var keyword=document.getElementById("keyword").value;
//發出非同步請求
xmlHttp.open("GET",keyupAddress+keyword,true);
xmlHttp.onreadystatechange=handlereadystatechange;
xmlHttp.send(null);
}
catch(e)
...{
displayError(e.toString);
}
}
}
}
////////////////////////////////////////////////// /////////
//3. 回呼函數,server端回應狀態改變後激發此函數
////////////////////////////////////////////////// /////////
function handlereadystatechange()
...{
if(xmlHttp.readyState==4)
...{
if(xmlHttp.status==200)
...{
try
...{
//取得server端回應
var xmlResponse = xmlHttp.responseXML;
suggestArray=xmlResponse.getElementsByTagName("suggest");
var showText="";
for(var i=0;i ...{
var textNodes=suggestArray[i].getElementsByTagName("text");
var timesNodes=suggestArray[i].getElementsByTagName("times");
for(var j=0;j ...{
showText+=textNodes[j].childNodes[0].nodeValue+" ("+timesNodes[j].childNodes[0].nodeValue+")
";
}
}
//顯示回應到頁面中
display(showText);
}
catch(e)
...{
displayError(e.toString());
}
}
}
}
////////////////////////////////////////////////// /////////
//2. event-driven函數(search函數)
////////////////////////////////////////////////// /////////
var searchAddress="php/suggest.php?action=search&keyword=";
function search()
...{
if(xmlHttp)
...{
//server不忙的時候發送非同步請求
if(xmlHttp.readyState==0||xmlHttp.readyState==4)
...{
try
...{
var keyword=document.getElementById("keyword").value;
//發出非同步請求
xmlHttp.open("GET",searchAddress+keyword,true);
xmlHttp.onreadystatechange=handlereadystatechange;
xmlHttp.send(null);
}
catch(e)
...{
displayError(e.toString);
}
}
}
}

最後注意：Server端PHP腳本的程式架構(suggest.php為Server端的主要處理函數，另外suggest.class.php,error_handler.php,config.php等)
suggest.php(取得Client端的參數，並呼叫suggest類別的兩個方法，產生XML格式的回應發回Client端)
require_once('suggest.class.php');
header('Content-Type: text/xml');
//確定使用者瀏覽器不會快取結果
header('Expires: Wed, 23 Dec 1980 00:30:00 GMT');
header('Last-Modified: '.gmdate('D, d MYH:i:s').' GMT' );
header('Cache-Control: no-cache, must-revalidate');
header('Pragma: no-cache');

$action=$_GET['action'];
$keyword=$_GET['keyword'];

$oSuggest=new suggest();
if($action=='keyup'&&$keyword!='')
{
$suggestXML=$oSuggest->getSuggests($keyword);
}
if($action=='search'&&$keyword!='')
{
$suggestXML=$oSuggest->submitKeyword($keyword);
}
echo $suggestXML;
?>suggest.class.php類
require_once('error_handler.php');
require_once('config.php');
class suggest
{
//成員變數
private $conn;

//建構子, 資料庫鏈接
function __construct()
{
$this->conn=new mysqli(DB_HOST, DB_USER, DB_PASSWORD, DB_DATABASE);
if (mysqli_connect_errno()) {
printf("Connect failed: %s ", mysqli_connect_error());
exit();
}
}
//析構函數,斷開資料庫鏈接
function __destruct()
{
$this->conn->close();
}
//getSuggests成員函數(函數主要回應Client端action=keyup，即使用者正在輸入時候的非同步請求)
public function getSuggests($keyword)
{
//產生suggest(產生資料庫中與所輸入關鍵字前半部相同的關鍵字)
$suggest_query='select * from keywords where keyword like ''.$keyword.'%' order by times desc limit 5';
$suggest_result=$this->conn->query($suggest_query);
$suggest_num=$suggest_result->num_rows;

$strOUT='';
if($suggest_num==0)
{
//$strOUT=$strOUT.''.$keyword.'0';
}
else
{
$strOUT=$strOUT."";
for($i=0;$i<$suggest_num;$i++)
{
$suggest_row = $suggest_result->fetch_row();
$strOUT=$strOUT.''.$suggest_row[1].''.$suggest_row[2].'';
}
$strOUT=$strOUT.'';
}
return $strOUT;
}
//submitKeyword成員函數(此函數主要回應Client端action=search，即使用者點擊search時候的非同步請求)
public function submitKeyword($keyword)
{
$select_query='select * from keywords where keyword=''.$keyword.''';
$select_result=$this->conn->query($select_query);
$select_num=$select_result->num_rows;

//遇到新的keywords加入資料庫中，遇到已有的keywords增加次數
$strOUT='';
//已經存在,增加次數
if($select_num!=0)
{
$select_row = $select_result->fetch_row();
$times_now=$select_row[2];
$times_now=$times_now+1;
$update_query='update keywords set times ='.$times_now.' where keyword=''.$keyword.''';
$update_result=$this->conn->query($update_query);
$strOUT=$strOUT.''.$keyword.''.$times_now.'';
}
else
{
//不存在保存插入
$insert_query='insert into keywords(keyword, times) values (''.$keyword.'',1)';
$insert_result=$this->conn->query($insert_query);
$strOUT=$strOUT.''.$keyword.'1';
}
return $strOUT;
}
}
?>
最後兩個函數，config.php保存應用程式設定資訊(如資料庫設定資訊)
define('DB_HOST', 'localhost');
define('DB_USER','phpajaxuser');
define('DB_PASSWORD','phpajaxuser');
define('DB_DATABASE','phpajax');
?>
error_handler.php保存自訂異常處理
//設定使用者自訂錯誤處理函數
set_error_handler('error_handler', E_ALL);

function error_handler($errNo,$errStr,$errFile,$errLine)
{
if(ob_get_length()) ob_clean();

$error_message='ERRNO: '.$errNo.chr(10).'TEXT: '.$errStr.chr(10).'LOCATION: '.$errFile.' Line: '.$errLine;
echo $error_message;
exit;
}
?>最後還需要sql語句在資料庫中加入用來保存keywords的database
CREATE TABLE `keywords` (
`id` int(10) unsigned NOT NULL auto_increment,
`keyword` varchar(32) NOT NULL default '',
`times` int(10) unsigned NOT NULL default '0',
PRIMARY KEY (`id`)
) TYPE=MyISAM AUTO_INCREMENT=1 ;

6.關於PHP的小知識，以後研究：
PHP從遠端伺服器讀取資料的方法(有點類似Web Crawl)：
file_get_contents;
或CURLwww.php.net/curl