google maps 如何显示文字或者数字，且为动态的
如题：
google maps 如何根据经纬度显示文字或者数字，且为动态的。（JavaScript实现）
例：根据给定经纬度，显示一些数字，并且这些数字是动态显示的，每3s或者其他时间显示不同数据！
[解决办法]
显示自定义文本/图片的话，你需要创建一个自定义的覆盖层。给你一个改编自官方谷歌文档的例子，你自己参考一下吧。

           //adapded from this example http://code.google.com/apis/maps/documentation/javascript/overlays.html#CustomOverlays
            //text overlays
            function TxtOverlay(pos, txt, cls, map){

                // Now initialize all properties.
                this.pos = pos;
                this.txt_ = txt;
                this.cls_ = cls;
                this.map_ = map;

                // We define a property to hold the image's
                // div. We'll actually create this div
                // upon receipt of the add() method so we'll
                // leave it null for now.
                this.div_ = null;

                // Explicitly call setMap() on this overlay
                this.setMap(map);
            }

            TxtOverlay.prototype = new google.maps.OverlayView();



            TxtOverlay.prototype.onAdd = function(){

                // Note: an overlay's receipt of onAdd() indicates that
                // the map's panes are now available for attaching
                // the overlay to the map via the DOM.

                // Create the DIV and set some basic attributes.
                var div = document.createElement('DIV');
                div.className = this.cls_;

                div.innerHTML = this.txt_;

                // Set the overlay's div_ property to this DIV
                this.div_ = div;
                var overlayProjection = this.getProjection();
                var position = overlayProjection.fromLatLngToDivPixel(this.pos);
                div.style.left = position.x + 'px';
                div.style.top = position.y + 'px';
                // We add an overlay to a map via one of the map's panes.

                var panes = this.getPanes();
                panes.floatPane.appendChild(div);
            } 
 
            TxtOverlay.prototype.draw = function(){


                var overlayProjection = this.getProjection();

                // Retrieve the southwest and northeast coordinates of this overlay
                // in latlngs and convert them to pixels coordinates.
                // We'll use these coordinates to resize the DIV.
                var position = overlayProjection.fromLatLngToDivPixel(this.pos);


                var div = this.div_;
                div.style.left = position.x + 'px';
                div.style.top = position.y + 'px';



            }
           //Optional: helper methods for removing and toggling the text overlay.  
            TxtOverlay.prototype.onRemove = function(){
                this.div_.parentNode.removeChild(this.div_);
                this.div_ = null;
            }
            TxtOverlay.prototype.hide = function(){
                if (this.div_) {
                    this.div_.style.visibility = "hidden";
                }
            }

            TxtOverlay.prototype.show = function(){
                if (this.div_) {
                    this.div_.style.visibility = "visible";
                }
            }

            TxtOverlay.prototype.toggle = function(){
                if (this.div_) {
                    if (this.div_.style.visibility == "hidden") {
                        this.show();
                    }
                    else {
                        this.hide();
                    }
                }
            }

            TxtOverlay.prototype.toggleDOM = function(){
                if (this.getMap()) {
                    this.setMap(null);
                }
                else {
                    this.setMap(this.map_);
                }
            }




            var map;

            function init(){ 
 
                var latlng = new google.maps.LatLng(37.9069, -122.0792);
                var myOptions = {
                    zoom: 4,
                    center: latlng,
                    mapTypeId: google.maps.MapTypeId.ROADMAP
                };
                map = new google.maps.Map(document.getElementById("map"), myOptions);

                var marker = new google.maps.Marker({
                    position: latlng,
                    map: map,
                    title: "Hello World!"
                });

                customTxt = "<div>Blah blah sdfsddddddddddddddd ddddddddddddddddddddd<ul><li>Blah 1<li>blah 2 </ul></div>"
                txt = new TxtOverlay(latlng,customTxt,"customBox",map )

            }
        </script>
        <style>
            .customBox {
                background: yellow;
                border: 1px solid black;
                position: absolute;

            }
        </style>
    </head>
    <body onload="init()">
        <div id="map" style="width: 600px; height: 600px;">
        </div>
    </body>
</html>