时间:2021-07-01 10:21:17 帮助过:34人阅读
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。
点击允许,获取坐标信息。
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:
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Gxl网其它相关文章!