PHP+AJAX无刷新返回天气预报

AjaxJavaScript天气预报php天气预报，用php来写一个天气预报的模块。

天气数据是通过采集中国气象网站的。本来中国天气网站也给出了数据的API接口。以下是API的地址。返回的数据格式为json格式。

1. http://www.weather.com.cn/data/sk/101010100.html

2. http://www.weather.com.cn/data/cityinfo/101010100.html

3. http://m.weather.com.cn/data/101010100.html

URL中的数字”101010100“是城市代码。所以可以先列出每个城市的城市代码，然后php程序接收到了城市代码，再去组装URL，在通过URL来显示该城市的实时天气。

index.php

<?php
    header("Content-Type:text/html;charset=utf-8");
?>
<html>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8" />
<head>
<title>weather forecast天气预报--www.jbxue.com</title>
<script type="text/javascript" src="ajax.js"></script>
<script type="text/javascript">
    function $(id){
        return document.getElementById(id);
    }
    function getCityId(){
        var http_request=createAjax();
        var url="weatherforecast.php"
        var data="cityid="+$("cityId").value;
        http_request.onreadystatechange=getWetherInfo;
        http_request.open("post",url,true);
        http_request.setRequestHeader("Content-type","application/x-www-form-urlencoded");
        http_request.send(data);
        function getWetherInfo(){
            if(http_request.readyState==4 && http_request.status==200){
                var info=http_request.responseText;
                $("weatherinfo").innerHTML=info;
            }
        }
    }
</script>
</head>
<body>
<select name="cityId" onchange="getCityId();" id="cityId">
    <option>--请选择城市--</option>
    <option value="101010100">北京</option>
    <option value="101020100">上海</option>
    <option value="101030100">天津</option>
    <option value="101040100">重庆</option>
    <option value="101280101">广州</option>
</select>
<span id="weatherinfo"></span>
</body> </html>

weatherforecast.php

<?php
header("Content-Type:text/html;charset=utf-8");
header("Cache-Control:no-cache");
    if (isset($_POST['cityid'])){
        $cityid=$_POST['cityid'];
        $url=$url="http://www.weather.com.cn/data/sk/".$cityid.".html";
    }else {
        $url="http://www.weather.com.cn/data/sk/101010100.html";
    }
    $weatherInfo_json=file_get_contents($url);
    $weatherInfo=json_decode($weatherInfo_json,true);
    $cityName=$weatherInfo['weatherinfo']['city'];
    $cityTemp=$weatherInfo['weatherinfo']['temp'];
    $cityWd=$weatherInfo['weatherinfo']['WD'];
    $cityWs=$weatherInfo['weatherinfo']['WS'];
    $cityTime=$weatherInfo['weatherinfo']['time'];
    $citySD=$weatherInfo['weatherinfo']['SD'];
    echo $weatherinfo="城市名字：$cityName,气温：$cityTemp,风向：$cityWd";
?>