我已经在Google地图上找到了 here 上的PHP / MYSQL教程。
我希望每隔5秒左右从数据库中更新标记。
我的理解是我需要使用Ajax周期性更新标记，但我很难理解在哪里添加函数以及在哪里使用 setTimeout（）等
我发现的所有其他例子并没有真正解释发生了什么，一些有用的指导会非常棒！
这是我的代码（与Google示例相同，其中包含 var 更改）：
function load() {
var map = new google.maps.Map(document.getElementById("map"), {
center: new google.maps.LatLng(37.80815648152641, 140.95355987548828),
zoom: 13,
mapTypeId: 'roadmap'
});
var infoWindow = new google.maps.InfoWindow;
// Change this depending on the name of your PHP file
downloadUrl("nwmxml.php", function(data) {
var xml = data.responseXML;
var markers = xml.documentElement.getElementsByTagName("marker");
for (var i = 0; i < markers.length; i++) {
var host = markers[i].getAttribute("host");
var type = markers[i].getAttribute("active");
var lastupdate = markers[i].getAttribute("lastupdate");
var point = new google.maps.LatLng(
parseFloat(markers[i].getAttribute("lat")),
parseFloat(markers[i].getAttribute("lng")));
var html = "<b>" + "Host: </b>" + host + "<br>" + "<b>Last Updated: </b>" + lastupdate + "<br>";
var icon = customIcons[type] || {};
var marker = new google.maps.Marker({
map: map,
position: point,
icon: icon.icon,
shadow: icon.shadow
});
bindInfoWindow(marker, map, infoWindow, html);
}
});
}
function bindInfoWindow(marker, map, infoWindow, html) {
google.maps.event.addListener(marker, 'click', function() {
infoWindow.setContent(html);
infoWindow.open(map, marker);
});
}
function downloadUrl(url, callback) {
var request = window.ActiveXObject ?
new ActiveXObject('Microsoft.XMLHTTP') :
new XMLHttpRequest;
request.onreadystatechange = function() {
if (request.readyState == 4) {
request.onreadystatechange = doNothing;
callback(request, request.status);
}
};
request.open('GET', url, true);
request.send(null);
}
function doNothing() {}
我希望有人可以帮助我！
答案 0 :(得分：4)
请注意我没有测试过这个，因为我没有带有xml方便的数据库
首先，您需要将load（）函数拆分为初始化地图的函数。在domready上加载标记，以及稍后用于处理xml＆amp;用地图更新地图。这需要完成，这样就不会在每次加载时重新初始化地图。
其次，您需要决定如何处理已在地图上绘制的标记。为此，您需要在将它们添加到地图时将它们添加到数组中。在第二次更新时，您可以选择重绘标记（重建阵列）或只更新现有阵列。我的示例显示了您只需从屏幕清除旧标记的情况（更简单）。
//global array to store our markers
var markersArray = [];
var map;
function load() {
map = new google.maps.Map(document.getElementById("map"), {
center : new google.maps.LatLng(37.80815648152641, 140.95355987548828),
zoom : 13,
mapTypeId : 'roadmap'
});
var infoWindow = new google.maps.InfoWindow;
// your first call to get & process inital data
downloadUrl("nwmxml.php", processXML);
}
function processXML(data) {
var xml = data.responseXML;
var markers = xml.documentElement.getElementsByTagName("marker");
//clear markers before you start drawing new ones
resetMarkers(markersArray)
for(var i = 0; i < markers.length; i++) {
var host = markers[i].getAttribute("host");
var type = markers[i].getAttribute("active");
var lastupdate = markers[i].getAttribute("lastupdate");
var point = new google.maps.LatLng(parseFloat(markers[i].getAttribute("lat")), parseFloat(markers[i].getAttribute("lng")));
var html = "<b>" + "Host: </b>" + host + "<br>" + "<b>Last Updated: </b>" + lastupdate + "<br>";
var icon = customIcons[type] || {};
var marker = new google.maps.Marker({
map : map,
position : point,
icon : icon.icon,
shadow : icon.shadow
});
//store marker object in a new array
markersArray.push(marker);
bindInfoWindow(marker, map, infoWindow, html);
}
// set timeout after you finished processing & displaying the first lot of markers. Rember that requests on the server can take some time to complete. SO you want to make another one
// only when the first one is completed.
setTimeout(function() {
downloadUrl("nwmxml.php", processXML);
}, 5000);
}
//clear existing markers from the map
function resetMarkers(arr){
for (var i=0;i<arr.length; i++){
arr[i].setMap(null);
}
//reset the main marker array for the next call
arr=[];
}
function bindInfoWindow(marker, map, infoWindow, html) {
google.maps.event.addListener(marker, 'click', function() {
infoWindow.setContent(html);
infoWindow.open(map, marker);
});
}
function downloadUrl(url, callback) {
var request = window.ActiveXObject ? new ActiveXObject('Microsoft.XMLHTTP') : new XMLHttpRequest;
request.onreadystatechange = function() {
if(request.readyState == 4) {
request.onreadystatechange = doNothing;
callback(request, request.status);
}
};
request.open('GET', url, true);
request.send(null);
}
答案 1 :(得分：1)
setInterval(function() {
downloadUrl("conection/cargar_tecnicos.php", function(data) {
var xml = data.responseXML;
markers = xml.documentElement.getElementsByTagName("marker");
removeAllMarkers();
for (var i = 0; i < markers.length; i++) {
var name = markers[i].getAttribute("name");
var fecha = markers[i].getAttribute("fecha");
var id_android = markers[i].getAttribute("id_android");
var celular = markers[i].getAttribute("celular");
var id = markers[i].getAttribute("id");
var logo = markers[i].getAttribute("logo");
var type = markers[i].getAttribute("type");
var point = new google.maps.LatLng(
parseFloat(markers[i].getAttribute("lat")),
parseFloat(markers[i].getAttribute("lng")));
var html = "<div class='infowindow'>"
+"<br/><div style='text-align:center;'><img src="+logo+"><br/>"
+"<b>" + name + "</b></div><br/>"
+"<br/><label><b>Celular:</b></label>" + celular+""
+"<br/><label><b>Id Android:</b></label>" + id_android+""
+"<br/><label><b>Fecha y Hora:</b></label>" + fecha+""
+"<br/><br/><div style='text-align:center;'><a><input style=';' id='pop' type='image' value='"+id+"' class='ASD' img src='img/vermas.png' title='Detalles'/></a></div></div>";
var icon = customIcons[type] || {};
marker[i] = new google.maps.Marker({
position: point,
icon: icon.icon,
shadow: icon.shadow,
title:name
});
openInfoWindow(marker[i], map, infoWindow, html);
marker[i].setMap(map);
}
});
},10000);
}
function removeAllMarkers(){// removes all markers from map
for( var i = 0; i < marker.length; i++ ){
marker[i].setMap(null);
}
}