openlayers中利用vector实现marker的方式

项目需要一个小型的gis。openlayers，geoserver，postgres组合是比较好的选择。
openlayers的marker层好像不支持拖动操作。通过研究api发现，可以利用vector层
达到这个目的，作出标注的效果。可以定位，搜索，拖动等效果，选中的时候可以
通过修改style达到动画效果。
基本做法如下：
1：定义marker显示的样式
2：扩展vector层，利用在扩展层上添加point与style，图片显示point就出现标注的
   效果
基本代码如下:
定义样式：

$package("com.bct.map");
com.bct.map.EncoderMarkerStyle = {
	'bigEncoder':{
    	graphicWidth:24,
        graphicHeight : 24,
        graphicXOffset : -12,
        graphicYOffset : -24,
        externalGraphic : "scripts/map/img/channel2.png"
    },
    'smallEncoder':{
        graphicWidth:16,
        graphicHeight : 16,
        graphicXOffset : -8,
        graphicYOffset : -16,
        externalGraphic : "scripts/map/img/channel.gif"
    },
    'selectStyle':{
        pointerEvents: "visiblePainted",
        border:"border:25 outset #ff88ff",
        cursor: "pointer",
        graphicWidth:24,
        graphicHeight : 24,
        graphicXOffset : -12,
        graphicYOffset : -24,
        externalGraphic : "scripts/map/img/channel2.png"    
    },
    styleMap: new OpenLayers.StyleMap({
                    "select": new OpenLayers.Style({pointRadius: 24})
    })
}

2:扩展向量层

$package("com.bct.map");
$import("com.bct.map.EncoderMarkerStyle");
com.bct.map.MarkerVectorLayer = OpenLayers.Class(OpenLayers.Layer.Vector,{
    /**
	 * parameters
	 * attribute filer对象
	 */
	getFeatureByAttribute :function(attributes){
		var feature = null;
		for(var i=0;i<this.features.length; ++i){
			var attri = this.features[i].attributes;
			var find = false;
			for(var j in attributes){
				if(attributes[j] == attri[j]){
					find = true;
				}
			}
			if(find){
				return this.features[i]; 
			}			
		}
	
	},
	//添加Feature，是point显示为图片
	addEncorderFeature:function(encNode,location){
		if(encNode&&this.repetitiveCheck(encNode.id)){
			return;
		}
        var attributes = OpenLayers.Util.extend({}, encNode.attributes);
        var enc_point = new OpenLayers.Geometry.Point(location.lon,location.lat);
        var enc_Feature = new OpenLayers.Feature.Vector(enc_point,attributes,com.bct.map.EncoderMarkerStyle['smallEncoder']);
        this.addFeatures([enc_Feature]);
        if(encNode.attributes['lon']&&encNode.attributes['lat']&&encNode.attributes['lon'].length>0){
        	return;
        }
        this.updateChannel(encNode.id,location.lon,location.lat);
	},
	repetitiveCheck:function(entity_id){
	    if(this.getFeatureByAttribute({id:entity_id})){
	    	return true;
	    }
		return false;
	},
	updateChannel:function(channel_id,lon,lat){
		Ext.Ajax.request({
  			 url: 'deviceVideoEncoder.do?method=updateLonlat&id='+channel_id+"&lon="+lon+"&lat="+lat
		});
	},
	channelMarkerClick:function() {
	    var features = this.selectedFeatures;
    	if(features.length >=0&&features[0]) {
    		feature = features[0];            
            var treeNodeAttribute = feature.attributes;
			//显示信息   	
    	}
    },
    cartoonFeature :function(feature){
    	this.drawFeature(feature,com.bct.map.EncoderMarkerStyle['bigEncoder']);
        var runner = new Ext.util.TaskRunner(1000);
        var task = {
	    	run:this.drawFeature,
	    	scope:this,
	    	args:[feature,com.bct.map.EncoderMarkerStyle['smallEncoder']],
	    	interval: 1000
		}
    	runner.start(task);
    },
    removeSelectFeature:function(){
    	var features = this.selectedFeatures;
    	for(var i=features.length-1; i>=0; i--) {
            feature = features[i];
            this.updateChannel(feature.attributes['id'],"","");
        }
        this.destroyFeatures(this.selectedFeatures);
    },
    monitorSelectFeature:function(){		
    	var features = this.selectedFeatures;
    	if(features.length >=0&&features[0]) {
            feature = features[0];            
            var treeNodeAttribute = feature.attributes;
			var objId="mapAVShow"+treeNodeAttribute['id'];
			//弹出窗口
        }
    }
});

addEncorderFeature是添加一个标注的地方。
利用这种方式，比原有的marker层拥有更多的功能