PHP 示例 - AJAX 实时搜索
AJAX 可用于创建更用户友好且交互性更强的搜索。
AJAX 实时搜索
下面的示例将演示一个实时搜索，您可以在键入时获取搜索结果。
与传统搜索相比，实时搜索有许多优点
- 键入时显示结果
- 继续键入时结果会缩小
- 如果结果过于狭窄，请删除字符以查看更广泛的结果
在下面的输入字段中搜索 W3Schools 页面
上面示例中的结果来自一个 XML 文件（links.xml）。为了使此示例简单明了，只有六个结果可用。
示例说明 - HTML 页面
当用户在上面的输入字段中键入字符时，将执行 "showResult()" 函数。该函数由 "onkeyup" 事件触发
<html>
<head>
<script>
function showResult(str) {
if (str.length==0) {
document.getElementById("livesearch").innerHTML="";
document.getElementById("livesearch").style.border="0px";
return;
}
var xmlhttp=new XMLHttpRequest();
xmlhttp.onreadystatechange=function() {
if (this.readyState==4 && this.status==200) {
document.getElementById("livesearch").innerHTML=this.responseText;
document.getElementById("livesearch").style.border="1px solid #A5ACB2";
}
}
xmlhttp.open("GET","livesearch.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
<input type="text" size="30" onkeyup="showResult(this.value)">
<div id="livesearch"></div>
</form>
</body>
</html>源代码解释
如果输入字段为空（str.length==0），则函数清除 livesearch 占位符的内容并退出函数。
如果输入字段不为空，则 showResult() 函数执行以下操作
- 创建一个 XMLHttpRequest 对象
- 创建服务器响应准备好时要执行的函数
- 将请求发送到服务器上的文件
- 请注意，参数 (q) 已添加到 URL（包含输入字段的内容）
PHP 文件
由上面的 JavaScript 调用的服务器上的页面是名为 "livesearch.php" 的 PHP 文件。
“livesearch.php”中的源代码会在 XML 文件中搜索与搜索字符串匹配的标题，并返回结果
<?php
$xmlDoc=new DOMDocument();
$xmlDoc->load("links.xml");
$x=$xmlDoc->getElementsByTagName('link');
//从 URL 获取 q 参数
$q=$_GET["q"];
//如果 q 的长度大于 0，则查找 xml 文件中的所有链接
if (strlen($q)>0) {
$hint="";
for($i=0; $i<($x->length); $i++) {
$y=$x->item($i)->getElementsByTagName('title');
$z=$x->item($i)->getElementsByTagName('url');
if ($y->item(0)->nodeType==1) {
//查找匹配搜索文本的链接
if (stristr($y->item(0)->childNodes->item(0)->nodeValue,$q)) {
if ($hint=="") {
$hint="<a href='" .
$z->item(0)->childNodes->item(0)->nodeValue .
"' target='_blank'>" .
$y->item(0)->childNodes->item(0)->nodeValue . "</a>";
} else {
$hint=$hint . "<br /><a href='" .
$z->item(0)->childNodes->item(0)->nodeValue .
"' target='_blank'>" .
$y->item(0)->childNodes->item(0)->nodeValue . "</a>";
}
}
}
}
}
//如果找不到提示，则将输出设置为“无建议”
//或正确的值
if ($hint=="") {
$response="no suggestion";
} else {
$response=$hint;
}
//输出响应
echo $response;
?>
如果 JavaScript 发送了任何文本（strlen($q) > 0），则会发生以下情况
- 将 XML 文件加载到新的 XML DOM 对象中
- 循环遍历所有
元素，以查找与从 JavaScript 发送的文本匹配的内容</li> <li>将正确的 URL 和标题设置为 "$response" 变量。如果找到多个匹配项，所有匹配项都将添加到该变量中</li> <li>如果没有找到匹配项，则 $response 变量设置为 "no suggestion"</li> </ul> <br /> <div class="w3-clear nextprev"> <a class="w3-left w3-btn" href="php_ajax_xml.asp">❮ 上一页</a> <a class="w3-right w3-btn" href="php_ajax_poll.asp">下一页 ❯</a></div> <div id="user-profile-bottom-wrapper" class="user-profile-bottom-wrapper"> <div class="user-authenticated w3-hide"> <a href="https://profile.w3schools.com/log-in?redirect_url=https%3A%2F%2Fmy-learning.w3schools.com" class="user-profile-btn ga-bottom ga-bottom-profile" title="Your W3Schools Profile" aria-label="Your W3Schools Profile" target="_top"> <svg xmlns="http://www.w3.org/2000/svg" version="1.1" viewBox="0 0 2048 2048" class="user-profile-icon" aria-label="Your W3Schools Profile Icon"> <path d="M 843.500 1148.155 C 837.450 1148.515, 823.050 1149.334, 811.500 1149.975 C 742.799 1153.788, 704.251 1162.996, 635.391 1192.044 C 517.544 1241.756, 398.992 1352.262, 337.200 1470 C 251.831 1632.658, 253.457 1816.879, 340.500 1843.982 C 351.574 1847.431, 1696.426 1847.431, 1707.500 1843.982 C 1794.543 1816.879, 1796.169 1632.658, 1710.800 1470 C 1649.008 1352.262, 1530.456 1241.756, 1412.609 1192.044 C 1344.588 1163.350, 1305.224 1153.854, 1238.500 1150.039 C 1190.330 1147.286, 1196.307 1147.328, 1097 1149.035 C 1039.984 1150.015, 1010.205 1150.008, 950 1149.003 C 851.731 1147.362, 856.213 1147.398, 843.500 1148.155" stroke="none" fill="#2a93fb" fill-rule="evenodd"></path> <path d="M 1008 194.584 C 1006.075 194.809, 999.325 195.476, 993 196.064 C 927.768 202.134, 845.423 233.043, 786 273.762 C 691.987 338.184, 622.881 442.165, 601.082 552 C 588.496 615.414, 592.917 705.245, 611.329 760.230 C 643.220 855.469, 694.977 930.136, 763.195 979.321 C 810.333 1013.308, 839.747 1026.645, 913.697 1047.562 C 1010.275 1074.879, 1108.934 1065.290, 1221 1017.694 C 1259.787 1001.221, 1307.818 965.858, 1339.852 930.191 C 1460.375 795.998, 1488.781 609.032, 1412.581 451.500 C 1350.098 322.327, 1240.457 235.724, 1097.500 202.624 C 1072.356 196.802, 1025.206 192.566, 1008 194.584" stroke="none" fill="#0aaa8a" fill-rule="evenodd"></path> </svg> <svg xmlns="http://www.w3.org/2000/svg" class="user-progress" aria-label="Your W3Schools Profile Progress"> <path class="user-progress-circle1" fill="none" d="M 25.99650934151373 15.00000030461742 A 20 20 0 1 0 26 15"></path> <path class="user-progress-circle2" fill="none" d="M 26 15 A 20 20 0 0 0 26 15"></path> </svg> <span class="user-progress-star">★</span> <span class="user-progress-point">+1</span></a> </div> <div class="w3s-pathfinder -teaser user-anonymous w3-hide"> <div class="-background-image -variant-t2"> </div> <div class="-inner-wrapper"> <div class="-main-section"> <div class="-inner-wrapper"> <div class="-title">W3schools 学习路径</div> <div class="-headline">跟踪您的进度 - 免费！</div> <div class="-body"> <div class="-progress-bar"> <div class="-slider" style="width: 20%;"> </div> </div> </div> </div> </div> <div class="-right-side-section"> <div class="-user-session-btns"> <a href="https://profile.w3schools.com/log-in?redirect_url=https%3A%2F%2Fpathfinder.w3schools.com" class="-login-btn w3-btn bar-item-hover w3-right ws-light-green ga-bottom ga-bottom-login" title="登录您的账户" aria-label="登录您的账户" target="_top"> 登录 </a> <a href="https://profile.w3schools.com/sign-up?redirect_url=https%3A%2F%2Fpathfinder.w3schools.com" class="-signup-btn w3-button w3-right ws-green ws-hover-green ga-bottom ga-bottom-signup" title="注册以提升您的学习体验" aria-label="注册以提升您的学习体验" target="_top"> 注册 </a></div> </div> </div> </div> </div> </div> <div class="w3-col l2 m12" id="right"> <div class="sidesection"> <div id="skyscraper"> <div id="adngin-sidebar_top-0"></div> </div> </div> <style> .ribbon-vid { font-size:12px; 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