Original如何将经纬度利用Google Map API显示C# VS2005 Sample Code
日前写了一篇如何用GPS抓取目前所在,并回传至资料库储存,这篇将会利用这些回报的资料,将它显示在地图上,这个做法有两种,最简单的就是直接传值到Google Maps上.
举例来说,当我们知道经纬度后,只要将数据套到以下网址即可.
http://maps.google.com/maps?q=25.048346%2c121.516396
在参数q=后面,就可以加上经纬度了.
25.048346是Latitude纬度
%2c是空格
121.516396就是Longitude经度了.
范例画面:
而另一种做法就比这个复杂一点,要使用Google API来做,首先,要使用google API就必需要有google的帐号,没帐号是无法申请的,当有google的帐号后,就可以到http: //code.google.com/apis/maps/signup.html开始申请了.
最 下方My web site URL就输入各位的URL啰,如果输入的与执行google map api的URL不同,那就无法执行了.所以这个URL务必输入正确, 输入正确的URL并将上方的CheckBox打勾后,就可以按Generate API Key了,如果已经登入GOOGLE的,就不会再跳登入画面,之后就会跳到另一个画面,上面就有Key及Example Code了,当有了这些,就可以开始自己写Code了.
基本上,因为主要是Demo用的,所以设计介面很简单.
上面就一个DropDownList,因为先前的范例资料的关系,先手动在ITEM上加上1跟2.
而下方的地图,就跟申请API时的Example Code一样. 原始码如下:
<%@ Page language="C #" autoeventwireup="True" codefile="Default.aspx.cs" inherits="_default"%><! DOCTYPE HTML Public"-//w3c//dtd XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" >"Http://www.w3.org/1999/xhtml" >"Server" ><title>gps Location Map </title><script src="Http://maps.google.com/maps?file=api&v=2&key= Enter your Key"Type="Text/javascript" ></script><script src="Http://www.google.com/uds/api?file=uds.js&v=1.0&key= Enter your Key"Type="Text/javascript" ></script><script src="Http://www.google.com/uds/solutions/localsearch/gmlocalsearch.js" type="Text/javascript" ></script><style type="Text/css" > @import URL ("Http://www.google.com/uds/css/gsearch.css");@import URL ("Http://www.google.com/uds/solutions/localsearch/gmlocalsearch.css");</style><script type="Text/javascript" > <! [cdata[function Load (x,y,locationname) { if (gbrowseriscompatible ()) {var map =New GMap2 (document.getElementById ("Map"));var point =New Glatlng (x, y);Map.setcenter (Point, 16);Map.addoverlay (New Gmarker (point));Map.addcontrol (New Glargemapcontrol ());Map.addcontrol (New Gmaptypecontrol ());Map.addcontrol (New Gscalecontrol ());var LSC =New Google.maps.LocalSearch ();Map.addcontrol (New Google.maps.LocalSearch (),New Gcontrolposition (G_anchor_bottom_right,New Gsize (10,20));Map.openinfowindowhtml (Map.getcenter (), locationname);}} ]]></script><body id="Mainbody" runat="Server" ><form id="Form1" runat="Server" ><div><asp:dropdownlist id= "ddl_location" runat= "server" autopostback= "True" onselectedindexchanged= "ddl_location_selectedindexchanged" Width= span class= "str" > "500px" > <asp:ListItem>1</asp:ListItem> <asp:listitem value= " 2 ">2</asp:ListItem> </asp:dropdownlist><br/> <br/> <div id= span class= "str" > "map" style= </div> </div> </form> </body>
只要将"输入你的Key"的地方置换为你在Google MAP API申请到的Key即可.
protected void Page_Load (Object sender, EventArgs e){ if (! IsPostBack){ if (Request.QueryString.HasKeys ()){ string longitude = Request.QueryString.Get ("Lon"); String latitude = Request.QueryString.Get ("Lat"); String LN = Request.QueryString.Get (Server.urldecode ("LN")); this. MAINBODY.ATTRIBUTES.ADD ("OnLoad","Load (" + Longitude +"," + Latitude +", '" + LN +"‘)" );} Else{DataTable dt = GetLocation (Ddl_location.selectedvalue); if (dt. Rows.Count > 0){DataRow dr = dt. Rows[0]; this. MAINBODY.ATTRIBUTES.ADD ("OnLoad","Load (" + dr["Latitude"]. ToString () +"," + dr["Longitude"]. ToString () +", '" + dr["Updtime"]. ToString () +"‘)" );}}}} protected void ddl_location_selectedindexchanged (Object sender, EventArgs e){ Try{DataTable dt = GetLocation (Ddl_location.selectedvalue); if (dt. Rows.Count > 0){DataRow dr = dt. Rows[0]; this. MAINBODY.ATTRIBUTES.ADD ("OnLoad","Load (" + dr["Latitude"]. ToString () +"," + dr["Longitude"]. ToString () +", '" + dr["Updtime"]. ToString () +"‘)" );}} catch (Exception ex){Response.Write (ex. Message);}} Private DataTable GetLocation (String UID){ Try{ String strconn ="Data source=localhost;initial Catalog=gpsdb; User Id=gpsuser; Password=gpsuser; ";SqlConnection conn =New SqlConnection (strconn); string strcmd = "select Latitude,longitude,updtime from Gpsdb. Gpstrace where [email protected] "; SqlCommand cmd = new SqlCommand (STRCMD, conn); cmd. Parameters.addwithvalue ( "@UID", UID); SqlDataAdapter da = new SqlDataAdapter (CMD); DataTable dt= new DataTable (); da. Fill (DT); return dt; catch (Exception ex) { throw new Exception (ex. Message); } /span>
如此一来,就大功告成了,但或许有些人会有些遗问,那么MAP上,可以自订一些东西,例如不给搜寻列,这都是可以做到的,可以参考Google Map API Examples ,这里就有很多详细的说明.
感觉起来,GPS定位的想法部份,好像到此就没了,但在这过程中也发现到,其实Google Map有出Mobile版 的,而它的定位可不只是局限在GPS卫星讯号,而是可以用手机的讯号去定位,也就是说,他是透过手机与基地台之间的传输来计算出所在位置,这样就可以不受 到手机没有GPS功能模组或收不到卫星讯号所限制,这个概念其实也不算新,记得几年前的Run!PC杂志上就有篇文章是在介绍这个的,采用的技术是 Java.
不过不管如何,可以预见的是,这个的应用会愈来愈多元,谁说未来还要自己去用电脑下载图资再更新到自己的GPS装置上,装置上的地图永远会是最新的,加上Street View,也不用去看那电脑画出来的3D的道路图了,或许3G或无线上网的普及,这些运用将会更广泛.
参考资料:
Google Map API Examples
Google Map Mobile
原始码: GPSMap.zip
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