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：
Java代码
$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
Java代码

   1. $package("com.bct.map");  
   2. $import("com.bct.map.EncoderMarkerStyle");  
   3. com.bct.map.MarkerVectorLayer = OpenLayers.Class(OpenLayers.Layer.Vector,{  
   4.     /** 
   5.      * parameters 
   6.      * attribute filer对象 
   7.      */ 
   8.     getFeatureByAttribute :function(attributes){  
   9.         var feature = null;  
  10.         for(var i=0;i<this.features.length; ++i){  
  11.             var attri = this.features[i].attributes;  
  12.             var find = false;  
  13.             for(var j in attributes){  
  14.                 if(attributes[j] == attri[j]){  
  15.                     find = true;  
  16.                 }  
  17.             }  
  18.             if(find){  
  19.                 return this.features[i];   
  20.             }             
  21.         }  
  22.       
  23.     },  
  24.     //添加Feature，是point显示为图片  
  25.     addEncorderFeature:function(encNode,location){  
  26.         if(encNode&&this.repetitiveCheck(encNode.id)){  
  27.             return;  
  28.         }  
  29.         var attributes = OpenLayers.Util.extend({}, encNode.attributes);  
  30.         var enc_point = new OpenLayers.Geometry.Point(location.lon,location.lat);  
  31.         var enc_Feature = new OpenLayers.Feature.Vector(enc_point,attributes,com.bct.map.EncoderMarkerStyle['smallEncoder']);  
  32.         this.addFeatures([enc_Feature]);  
  33.         if(encNode.attributes['lon']&&encNode.attributes['lat']&&encNode.attributes['lon'].length>0){  
  34.             return;  
  35.         }  
  36.         this.updateChannel(encNode.id,location.lon,location.lat);  
  37.     },  
  38.     repetitiveCheck:function(entity_id){  
  39.         if(this.getFeatureByAttribute({id:entity_id})){  
  40.             return true;  
  41.         }  
  42.         return false;  
  43.     },  
  44.     updateChannel:function(channel_id,lon,lat){  
  45.         Ext.Ajax.request({  
  46.              url: 'deviceVideoEncoder.do?method=updateLonlat&id='+channel_id+"&lon="+lon+"&lat="+lat  
  47.         });  
  48.     },  
  49.     channelMarkerClick:function() {  
  50.         var features = this.selectedFeatures;  
  51.         if(features.length >=0&&features[0]) {  
  52.             feature = features[0];              
  53.             var treeNodeAttribute = feature.attributes;  
  54.             //显示信息        
  55.         }  
  56.     },  
  57.     cartoonFeature :function(feature){  
  58.         this.drawFeature(feature,com.bct.map.EncoderMarkerStyle['bigEncoder']);  
  59.         var runner = new Ext.util.TaskRunner(1000);  
  60.         var task = {  
  61.             run:this.drawFeature,  
  62.             scope:this,  
  63.             args:[feature,com.bct.map.EncoderMarkerStyle['smallEncoder']],  
  64.             interval: 1000 
  65.         }  
  66.         runner.start(task);  
  67.     },  
  68.     removeSelectFeature:function(){  
  69.         var features = this.selectedFeatures;  
  70.         for(var i=features.length-1; i>=0; i--) {  
  71.             feature = features[i];  
  72.             this.updateChannel(feature.attributes['id'],"","");  
  73.         }  
  74.         this.destroyFeatures(this.selectedFeatures);  
  75.     },  
  76.     monitorSelectFeature:function(){          
  77.         var features = this.selectedFeatures;  
  78.         if(features.length >=0&&features[0]) {  
  79.             feature = features[0];              
  80.             var treeNodeAttribute = feature.attributes;  
  81.             var objId="mapAVShow"+treeNodeAttribute['id'];  
  82.             //弹出窗口  
  83.         }  
  84.     }  
  85. });