欢迎您访问程序员文章站本站旨在为大家提供分享程序员计算机编程知识!
您现在的位置是: 首页  >  web前端

html5指南(4)-使用Geolocation的详解

程序员文章站 2023-12-23 12:20:04
...
  今天我们要学习的是使用Geolocation实现定位功能。我们可以通过navigator.geolocation获取Geolocation对象,他提供了下列方法:

getCurrentPosition(callback,errorCallback,options):获取当前位置;

watchPosition(callback,error,options):开始监控当前位置;

clearWatch(id):停止监控当前位置。

  note:下面例子使用的浏览器是chrome,使用其他浏览器我不能保证运行结果和例子显示的结果一致。

  1.获取当前位置

  我们将使用getCurrentPosition方法获取当前位置,位置信息不会以结果的形式直接返回,我们需要使用callback函数进行处理。在获取坐标的过程中会有些延迟,还会问你要访问权限。我们来看下面的例子:

<!DOCTYPE HTML><html><head>
    <title>Example</title>
    <style>
        table{border-collapse: collapse;}
        th, td{padding: 4px;}
        th{text-align: right;}
    </style></head><body>
    <table border="1">
        <tr>
            <th>Longitude:</th>
            <td id="longitude">-</td>
            <th>Latitude:</th>
            <td id="latitude">-</td>
        </tr>
        <tr>
            <th>Altitude:</th>
            <td id="altitude">-</td>
            <th>Accuracy:</th>
            <td id="accuracy">-</td>
        </tr>
        <tr>
            <th>Altitude Accuracy:</th>
            <td id="altitudeAccuracy">-</td>
            <th>Heading:</th>
            <td id="heading">-</td>
        </tr>
        <tr>
            <th>Speed:</th>
            <td id="speed">-</td>
            <th>Time Stamp:</th>
            <td id="timestamp">-</td>
        </tr>
    </table>
    <script>
        navigator.geolocation.getCurrentPosition(displayPosition);        
        function displayPosition(pos) {            
        var properties = ['longitude', 'latitude', 'altitude', 'accuracy', 'altitudeAccuracy', 'heading', 'speed'];            
        for (var i = 0, len = properties.length; i < len; i++) {                
        var value = pos.coords[properties[i]];
                document.getElementById(properties[i]).innerHTML = value;
               
            }
            document.getElementById('timestamp').innerHTML = pos.timestamp;
        }    </script></body></html>

  返回的position对象包含两个属性,coords:返回坐标信息;timestamp:获取坐标信息的时间。其中coords又包括下面属性:latitude:纬度;longitude:经度;altitude:高度;accuracy:精确度(米);altitudeAccuracy:高度精确度(米);heading:行进方向;speed:行进速度(米/秒)。

  并不是所有的信息都会返回,这取决于你承载浏览器的设备。像有GPS、加速器、罗盘的移动设备会返回大部分信息,家用电脑就不行了。家用电脑获取的位置信息,取决于所处的网络环境或者是wifi。下面我们看上例的运行结果。

html5指南(4)-使用Geolocation的详解

点击允许,获取坐标信息。

html5指南(4)-使用Geolocation的详解

  2.处理异常

  现在我们介绍getCurrentPosition的异常处理,他是通过使用errorCallback回调函数实现的。函数返回的参数error包含两个属性,code:错误类型的代码;message:错误信息。code包含三个值:1:用户没有授权使用geolocation;2:无法获取坐标信息;3:获取信息超时。

  下面我们看个例子:

<!DOCTYPE HTML><html><head>
    <title>Example</title>
    <style>
        table{border-collapse: collapse;}
        th, td{padding: 4px;}
        th{text-align: right;}
    </style></head><body>
    <table border="1">
        <tr>
            <th>Longitude:</th>
            <td id="longitude">-</td>
            <th>Latitude:</th>
            <td id="latitude">-</td>
        </tr>
        <tr>
            <th>Altitude:</th>
            <td id="altitude">-</td>
            <th>Accuracy:</th>
            <td id="accuracy">-</td>
        </tr>
        <tr>
            <th>Altitude Accuracy:</th>
            <td id="altitudeAccuracy">-</td>
            <th>Heading:</th>
            <td id="heading">-</td>
        </tr>
        <tr>
            <th>Speed:</th>
            <td id="speed">-</td>
            <th>Time Stamp:</th>
            <td id="timestamp">-</td>
        </tr>
        <tr>
            <th>Error Code:</th>
            <td id="errcode">-</td>
            <th>Error Message:</th>
            <td id="errmessage">-</td>
        </tr>
    </table>
    <script>
        navigator.geolocation.getCurrentPosition(displayPosition, handleError);        
        function displayPosition(pos) {            
        var properties = ["longitude", "latitude", "altitude", "accuracy", "altitudeAccuracy", "heading", "speed"];            
        for (var i = 0; i < properties.length; i++) {                
        var value = pos.coords[properties[i]];
                document.getElementById(properties[i]).innerHTML = value;
            }
            document.getElementById("timestamp").innerHTML = pos.timestamp;
        }        function handleError(err) {
            document.getElementById("errcode").innerHTML = err.code;
            document.getElementById("errmessage").innerHTML = err.message;
        }    </script></body></html>

  拒绝授权,运行结果:

html5指南(4)-使用Geolocation的详解

  

  3.使用geolocation可选参数项

  getCurrentPosition(callback,errorCallback,options)中的options有如下参数可以使用,enableHighAccuracy:使用最好的效果;timeout:超时时间(毫秒);maximumAge:指定缓存时间(毫秒)。我们来下下面的例子:

<!DOCTYPE HTML><html><head>
    <title>Example</title>
    <style>
        table{border-collapse: collapse;}
        th, td{padding: 4px;}
        th{text-align: right;}
    </style></head><body>
    <table border="1">
        <tr>
            <th>Longitude:</th>
            <td id="longitude">-</td>
            <th>Latitude:</th>
            <td id="latitude">-</td>
        </tr>
        <tr>
            <th>Altitude:</th>
            <td id="altitude">-</td>
            <th>Accuracy:</th>
            <td id="accuracy">-</td>
        </tr>
        <tr>
            <th>Altitude Accuracy:</th>
            <td id="altitudeAccuracy">-</td>
            <th>Heading:</th>
            <td id="heading">-</td>
        </tr>
        <tr>
            <th>Speed:</th>
            <td id="speed">-</td>
            <th>Time Stamp:</th>
            <td id="timestamp">-</td>
        </tr>
        <tr>
            <th>Error Code:</th>
            <td id="errcode">-</td>
            <th>Error Message:</th>
            <td id="errmessage">-</td>
        </tr>
    </table>
    <script>
        var options = {
            enableHighAccuracy: false,
            timeout: 2000,
            maximumAge: 30000
        };
        navigator.geolocation.getCurrentPosition(displayPosition, handleError, options);        
        function displayPosition(pos) {            
        var properties = ["longitude", "latitude", "altitude", "accuracy", "altitudeAccuracy", "heading", "speed"];            
        for (var i = 0; i < properties.length; i++) {                
        var value = pos.coords[properties[i]];
                document.getElementById(properties[i]).innerHTML = value;
            }
            document.getElementById("timestamp").innerHTML = pos.timestamp;
        }        function handleError(err) {
            document.getElementById("errcode").innerHTML = err.code;
            document.getElementById("errmessage").innerHTML = err.message;
        }    </script></body></html>

  4.监视位置变化

  下面我们介绍使用watchPosition方法实现位置变化的监视,他的使用方法和getCurrentPosition一样。我们来看例子:

<!DOCTYPE HTML><html><head>
    <title>Example</title>
    <style>
        table{border-collapse: collapse;}
        th, td{padding: 4px;}
        th{text-align: right;}
    </style></head><body>
    <table border="1">
        <tr>
            <th>Longitude:</th>
            <td id="longitude">-</td>
            <th>Latitude:</th>
            <td id="latitude">-</td>
        </tr>
        <tr>
            <th>Altitude:</th>
            <td id="altitude">-</td>
            <th>Accuracy:</th>
            <td id="accuracy">-</td>
        </tr>
        <tr>
            <th>Altitude Accuracy:</th>
            <td id="altitudeAccuracy">-</td>
            <th>Heading:</th>
            <td id="heading">-</td>
        </tr>
        <tr>
            <th>Speed:</th>
            <td id="speed">-</td>
            <th>Time Stamp:</th>
            <td id="timestamp">-</td>
        </tr>
        <tr>
            <th>Error Code:</th>
            <td id="errcode">-</td>
            <th>Error Message:</th>
            <td id="errmessage">-</td>
        </tr>
    </table>
    <button id="pressme">Cancel Watch</button>
    <script>
        var options = {
            enableHighAccuracy: false,
            timeout: 2000,
            maximumAge: 30000
        };        var watchID = navigator.geolocation.watchPosition(displayPosition, handleError, options);
        
        document.getElementById("pressme").onclick = function (e) {
            navigator.geolocation.clearWatch(watchID);
        };        function displayPosition(pos) {            
        var properties = ["longitude", "latitude", "altitude", "accuracy", "altitudeAccuracy", "heading", "speed"];            
        for (var i = 0; i < properties.length; i++) {                
        var value = pos.coords[properties[i]];
                document.getElementById(properties[i]).innerHTML = value;
            }
            document.getElementById("timestamp").innerHTML = pos.timestamp;
        }        function handleError(err) {
            document.getElementById("errcode").innerHTML = err.code;
            document.getElementById("errmessage").innerHTML = err.message;
        }    </script></body></html>

以上就是html5指南(4)-使用Geolocation的详解的详细内容,更多请关注其它相关文章!

相关标签: html5,Geolocation

上一篇:

下一篇: