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我有下一个代码可以从 xml 文件中检索一些数据。问题是当我想刷新标记时，我得到的响应是地图中的重复标记。如何在没有重复标记的情况下更新点？

此致

//<![CDATA[
  // this variable will collect the html which will eventually be placed in the       side_bar 
  var side_bar_html = ""; 

  // arrays to hold copies of the markers and html used by the side_bar 
  // because the function closure trick doesnt work there 
  var gmarkers = []; 

 // global "map" variable
  var map = null;
  var markerclusterer = null;

// A function to create the marker and set up the event window function 



function createMarker(latlng, imei, html, estado, alias, speed, timestamp) {
if(estado == 1)
  image = '/artworks/icons/truck_green3.png';
else
  image = '/artworks/icons/truck_red.png';
var textoLabel= "this is the text"
var contentString = html;
var marker = new MarkerWithLabel({
    position: latlng,
    icon: image,
    // map: map,
    labelContent: textoLabel,
   labelAnchor: new google.maps.Point(40, 0),
   labelClass: "labels", // the CSS class for the label
   labelStyle: {opacity: 0.50},
    zIndex: Math.round(latlng.lat()*-100000)<<5
    });


google.maps.event.addListener(marker, 'click', function() {
    infowindow.setContent(contentString); 
    infowindow.open(map,marker);
    });
// save the info we need to use later for the side_bar
gmarkers.push(marker);
// add a line to the side_bar html
side_bar_html += '<a href="javascript:myclick(' + (gmarkers.length-1) + ')">' + imei + '<\/a><br>';
}

    // This function picks up the click and opens the corresponding info window
function myclick(i) {
  google.maps.event.trigger(gmarkers[i], "click");
}



function initialize() {
  // create the map
  var myOptions = {
    zoom: 12,
    center: new google.maps.LatLng(37.169619,-3.756981),
    mapTypeControl: true,
    mapTypeControlOptions: {style: google.maps.MapTypeControlStyle.DROPDOWN_MENU},
    navigationControl: true,
    mapTypeId: google.maps.MapTypeId.ROADMAP
  }
  map = new google.maps.Map(document.getElementById("map_canvas"),
                            myOptions);
}
    function getMarkers() {
  google.maps.event.addListener(map, 'click', function() {
    infowindow.close();
    });
  // Read the data from example.xml
  downloadUrl("vehiculos.asp", function(doc) {
    var xmlDoc = xmlParse(doc);
    var markers = xmlDoc.documentElement.getElementsByTagName("marker");
    for (var i = 0; i < markers.length; i++) {
      // obtain the attribues of each marker
      var lat = parseFloat(markers[i].getAttribute("lat"));
      var lng = parseFloat(markers[i].getAttribute("lng"));
      var point = new google.maps.LatLng(lat,lng);
      var imei = markers[i].getAttribute("imei");
      var alias = markers[i].getAttribute("alias");
      var speed= markers[i].getAttribute("speed");
      var timestamp= markers[i].getAttribute("timestamp");
      var estado= markers[i].getAttribute("estado");
      var conectado= markers[i].getAttribute("conectado");
var html="<b>"+alias+"</b><br> a una velocidad de "+speed+" km/h <br/>     ultima posicion  a las: "+timestamp;

      // create the marker
      var marker = createMarker(point,alias+" "+imei,html,estado, speed, timestamp );
    }

    markerCluster = new MarkerClusterer(map, gmarkers);
    // put the assembled side_bar_html contents into the side_bar div
    document.getElementById("side_bar").innerHTML = side_bar_html;
  });
}

var infowindow = new google.maps.InfoWindow(
  { 
    size: new google.maps.Size(150,50)
 });

  // Removes the overlays from the map, but keeps them in the array.
  function clearOverlays() {
    getMarkers(null);
  }

  // Deletes all markers in the array by removing references to them.
  function deleteOverlays() {
    clearOverlays();
    getMarkers = [];
  }
setInterval(clearOverlays, 3000);
setInterval(deleteOverlays, 4000);
setInterval(getMarkers, 5000);
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1 回答 1

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为您的标记提供唯一的 ID（也许您现有的属性之一已经是唯一的）。如果唯一 ID 已经存在，则将该标记移动到新位置（或不再添加），如果不存在，则创建一个新标记。

如果它们不移动，您还可以通过检查新标记与所有现有标记之间的距离来避免重复，如果它小于“相同标记”阈值（例如 ~0.1 米），请不要再次添加它。

您的 clearOverlays 方法有问题（getMarkers(null) 只是调用 getMarkers）：

// Removes the overlays from the map, but keeps them in the array.
function clearOverlays() {
  for (var i=0; i<gmarkers.length; i++)
  {
     gmarkers[i].setMap(null);
  }
}
于 2012-10-24T18:48:22.260 回答