跨域之jsonp

た入场券 2021-09-19 05:24 349阅读 0赞

先创建一个html文件，代码如下：

1 <body>2    <p>名字：<span id="name"></span></p>3 <script>4   function test(obj) {5    document.getElementById("name").innerHTML = obj.name;6   }7 </script>8 </body>

此时在浏览器打开这个文件，页面中只有“名字：”这三个字符。

现在创建一个JS文件，test.js，其中的代码如下：

1 var person = {2     name: "Jack",3     age: 204 }5 test(person);

通过<script>标签在html文件中引入这个test.js文件（添加到body结束标签之前）：

1 <script src="test.js"></script>

再在浏览器中打开html文件就会看到：

![1005281-20161113144608827-1893814413.jpg][]

如果把这个test.js放在百度的服务器上，在淘宝的页面上有一个test函数声明，然后动态地创建一个<script>标签来引用这个test.js，那么在淘宝的页面上就可以显示来自百度的服务器的数据，这就是jsonp的原理。当然引用的不一定非要是js文件，也可以是php、.net等文件，只要在这些文件中事先写好相应的代码即可。

下面用聚合数据的天气预报接口和新浪的城市查询接口为例来介绍jsonp。

首先是新浪的城市查询接口。

新浪的城市查询接口是:

http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js

可以直接在浏览器中打开，发现是一个名为remote\_ip\_info的Javascript对象，

var remote_ip_info = {    "ret":1,    "start":-1,    "end":-1,    "country":"\u4e2d\u56fd",    "province":"\u6cb3\u5357",    "city":"\u8bb8\u660c",    "district":"",    "isp":"",    "type":"",    "desc":""};

那么在本地的测试页面中可以使用这个接口获取所在的城市，代码如下：

1 //获取当前城市 2     function getCity(url) { 3       var city = ''; 4       //创建一个script标签 5       var script = document.createElement("script"); 6       //设置script标签引用的url 7       script.setAttribute("src",url); 8       //将script标签添加到头部，也可以添加到其他地方 9       var head = document.getElementsByTagName('head')[0];10       head.appendChild(script);11       //如果script标签加载完成，获取城市12       script.onload = function() {//script.onload不兼容IE8及以下版本13          city = remote_ip_info["city"];14          console.log(city);15       };16 17       //移除创建的script标签18       head.removeChild(script);19     }20 21     //该URL是新浪的获取当前城市的API，采用jasop方法获取数据22     getCity("http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js");

下面是聚合数据的天气预报接口。

接口示例：http://op.juhe.cn/onebox/weather/query?cityname=%E6%B8%A9%E5%B7%9E&key=您申请的KEY

使用这个接口时至少要传入三个参数：

1.  cityname是要查询的城市名，可以用前面新浪的城市查询接口得到的数据。
2.  key是申请使用聚合数据天气预报接口时，给的APPKey。
3.  另外还有一个callback参数，传入一个函数名，服务器会把查询后得到的数据拼接成函数调用的形式返回来，比如传入test函数名，则返回来test(\{"date":"2011-11-11","wind":"微风"\})，所以要在测试页面声明好这个函数，以便对返回来的数据进行处理。

下面是代码：

html代码，将获得数据在页面中显示出来

1 <p id="chuanyi"></p>2 <p id="yundong"></p>3 <p id="ziwaixian"></p>

获得天气情况数据的代码，原理与获取当前城市的原理一样，不同的是要事先指定回调函数，并将函数名加到url的末尾。

1 function $(id) { 2       return document.getElementById(id); 3 } 4  5 //指定回调函数 6     function callback(data) { 7      $("chuanyi").innerHTML = "穿衣指数：" + data.result.data.life.info.chuanyi; 8      $("yundong").innerHTML = "运动指数：" + data.result.data.life.info.yundong; 9      $("ziwaixian").innerHTML = "紫外线：" + data.result.data.life.info.ziwaixian;10     }11 12     function getWeather(city) {13       var url = 'http://op.juhe.cn/onebox/weather/query?cityname='+encodeURIComponent(city)+'&key=abbac0fc4fccbec34891de77bb1cfb4e&callback=callback';//该URL是聚合数据的天气预报API，采用jasop方法获取数据14       console.log(encodeURIComponent(city));15       var script = document.createElement("script");16       script.setAttribute("src",url);17       var head = document.getElementsByTagName('head')[0];18       head.appendChild(script);19       head.removeChild(script);20     }

有了以上代码，还不能获取到天气数据，因为getWeather()函数还没有调用。为了能将获取到的城市数据传给getWeather()函数，要在getCity()函数内部script的onload事件处理程序中调用getWeather()函数。

下面是调用getWeather函数返回的数据，一大串：

![ExpandedBlockStart.gif][]

1 callback(\{  2     "reason":"successed!",  3     "result":\{  4         "data":\{  5             "pubdate":"2016-11-11",  6             "pubtime":"11:00:00",  7             "realtime":\{  8                 "city\_code":"101180401",  9                 "city\_name":"许昌", 10                 "date":"2016-11-11", 11                 "time":"16:00:00", 12                 "week":5, 13                 "moon":"十月十二", 14                 "dataUptime":1478853365, 15                 "weather":\{ 16                     "temperature":"15", 17                     "humidity":"64", 18                     "info":"多云", 19                     "img":"1" 20                 \}, 21                 "wind":\{ 22                     "direct":"南风", 23                     "power":"3级", 24                     "offset":null, 25                     "windspeed":null 26                 \} 27             \}, 28             "life":\{ 29                 "date":"2016-11-11", 30                 "info":\{ 31                     "chuanyi":\["较冷","建议着厚外套加毛衣等服装。年老体弱者宜着大衣、呢外套加羊毛衫。"\], 32                     "ganmao":\["较易发","天凉，昼夜温差较大，较易发生感冒，请适当增减衣服，体质较弱的朋友请注意适当防护。"\], 33                     "kongtiao":\["较少开启","您将感到很舒适，一般不需要开启空调。"\], 34                     "xiche":\["较适宜","较适宜洗车，未来一天无雨，风力较小，擦洗一新的汽车至少能保持一天。"\], 35                     "yundong":\["较适宜","天气较好，但考虑气温较低，推荐您进行室内运动，若户外适当增减衣物并注意防晒。"\], 36                     "ziwaixian":\["弱","紫外线强度较弱，建议出门前涂擦SPF在12-15之间、PA+的防晒护肤品。"\] 37                 \} 38             \}, 39             "weather":\[ 40                 \{ 41                     "date":"2016-11-11", 42                     "info":\{ 43                         "day":\["1","多云","17","","微风","06:53"\], 44                         "night":\["0","晴","7","","微风","17:23"\] 45                     \}, 46                     "week":"五", 47                     "nongli":"十月十二" 48                 \}, 49                 \{ 50                     "date":"2016-11-12", 51                     "info":\{ 52                         "dawn":\["0","晴","7","无持续风向","微风","17:23"\], 53                         "day":\["0","晴","17","","微风","06:54"\], 54                         "night":\["1","多云","8","","微风","17:23"\] 55                     \}, 56                     "week":"六", 57                     "nongli":"十月十三" 58                 \}, 59                 \{ 60                     "date":"2016-11-13", 61                     "info":\{ 62                         "dawn":\["1","多云","8","无持续风向","微风","17:23"\], 63                         "day":\["1","多云","17","","微风","06:55"\], 64                         "night":\["0","晴","9","","微风","17:22"\] 65                     \}, 66                     "week":"日", 67                     "nongli":"十月十四" 68                 \}, 69                 \{ 70                     "date":"2016-11-14", 71                     "info":\{ 72                         "dawn":\["0","晴","9","无持续风向","微风","17:22"\], 73                         "day":\["1","多云","17","","微风","06:56"\], 74                         "night":\["2","阴","5","","微风","17:21"\] 75                     \}, 76                     "week":"一", 77                     "nongli":"十月十五" 78                 \}, 79                 \{ 80                     "date":"2016-11-15", 81                     "info":\{ 82                         "dawn":\["2","阴","5","无持续风向","微风","17:21"\], 83                         "day":\["1","多云","13","","微风","06:57"\], 84                         "night":\["1","多云","6","","微风","17:21"\] 85                     \}, 86                     "week":"二", 87                     "nongli":"十月十六" 88                 \} 89             \], 90             "f3h":\{ 91                 "temperature":\[ 92                     \{ 93                         "jg":"20161111170000", 94                         "jb":"15" 95                     \}, 96                     \{ 97                         "jg":"20161111200000", 98                         "jb":"13" 99                     \},100                     \{101                         "jg":"20161111230000",102                         "jb":"10"103                     \},104                     \{105                         "jg":"20161112020000",106                         "jb":"10"107                     \},108                     \{109                         "jg":"20161112050000",110                         "jb":"8"111                     \},112                     \{113                         "jg":"20161112080000",114                         "jb":"7"115                     \},116                     \{117                         "jg":"20161112110000",118                         "jb":"14"119                     \},120                     \{121                         "jg":"20161112140000",122                         "jb":"16"123                     \},124                     \{125                         "jg":"20161112170000",126                         "jb":"14"127                     \}128                 \],129                 "precipitation":\[130                     \{"jg":"20161111170000","jf":"0"\},131                     \{"jg":"20161111200000","jf":"0"\},132                     \{"jg":"20161111230000","jf":"0"\},133                     \{"jg":"20161112020000","jf":"0"\},134                     \{"jg":"20161112050000","jf":"0"\},135                     \{"jg":"20161112080000","jf":"0"\},136                     \{"jg":"20161112110000","jf":"0"\},137                     \{"jg":"20161112140000","jf":"0"\},138                     \{"jg":"20161112170000","jf":"0"\}139                 \]140             \},141             "pm25":\{142                 "key":"Xuchang",143                 "show\_desc":0,144                 "pm25":\{145                     "curPm":"50",146                     "pm25":"25",147                     "pm10":"51",148                     "level":1,149                     "quality":"优",150                     "des":"可正常活动。"151                 \},152                 "dateTime":"2016年11月11日16时",153                 "cityName":"许昌"154             \},155             "jingqu":"",156             "jingqutq":"",157             "date":"",158             "isForeign":"0"159         \}160     \},161     "error\_code":0162 \})

本文转自zsdnr 51CTO博客，原文链接：http://blog.51cto.com/12942149/1928949，如需转载请自行联系原作者

[1005281-20161113144608827-1893814413.jpg]: /images/20210726/f339829b4c7c47bfa23627ea31f3b512.png
[ExpandedBlockStart.gif]: /images/20210726/06845d39ce5b40f9b63bdbbad74f8b92.png