wfs.js

用来在地图上做操作GIS,在地图上做标记

                this.addTileMonitoringHooks(this.tile);
                this.tile.draw();
            } else {
                if (this.vectorMode) {
                    this.destroyFeatures();
                    this.renderer.clear();
                } else {
                    this.clearMarkers();
                }    
                this.removeTileMonitoringHooks(this.tile);
                this.tile.destroy();
                
                this.tile = null;
                this.tile = new OpenLayers.Tile.WFS(this, pos, tileBounds, 
                                                     url, tileSize);
                this.addTileMonitoringHooks(this.tile);
                this.tile.draw();
            } 
        }
    },

    /** 
     * Method: addTileMonitoringHooks
     * This function takes a tile as input and adds the appropriate hooks to 
     *     the tile so that the layer can keep track of the loading tile
     *     (making sure to check that the tile is always the layer's current
     *     tile before taking any action).
     * 
     * Parameters: 
     * tile - {<OpenLayers.Tile>}
     */
    addTileMonitoringHooks: function(tile) {
        tile.onLoadStart = function() {
            //if this is the the layer's current tile, then trigger 
            // a 'loadstart'
            if (this == this.layer.tile) {
                this.layer.events.triggerEvent("loadstart");
            }
        };
        tile.events.register("loadstart", tile, tile.onLoadStart);
      
        tile.onLoadEnd = function() {
            //if this is the the layer's current tile, then trigger 
            // a 'tileloaded' and 'loadend'
            if (this == this.layer.tile) {
                this.layer.events.triggerEvent("tileloaded");
                this.layer.events.triggerEvent("loadend");
            }
        };
        tile.events.register("loadend", tile, tile.onLoadEnd);
    },
    
    /** 
     * Method: removeTileMonitoringHooks
     * This function takes a tile as input and removes the tile hooks 
     *     that were added in addTileMonitoringHooks()
     * 
     * Parameters: 
     * tile - {<OpenLayers.Tile>}
     */
    removeTileMonitoringHooks: function(tile) {
        tile.events.unregister("loadstart", tile, tile.onLoadStart);
        tile.events.unregister("loadend", tile, tile.onLoadEnd);
    },

    /**
     * Method: onMapResize
     * Call the onMapResize method of the appropriate parent class. 
     */
    onMapResize: function() {
        if(this.vectorMode) {
            OpenLayers.Layer.Vector.prototype.onMapResize.apply(this, 
                                                                arguments);
        } else {
            OpenLayers.Layer.Markers.prototype.onMapResize.apply(this, 
                                                                 arguments);
        }
    },
    
    /**
     * APIMethod: mergeNewParams
     * Modify parameters for the layer and redraw.
     * 
     * Parameters:
     * newParams - {Object}
     */
    mergeNewParams:function(newParams) {
        var upperParams = OpenLayers.Util.upperCaseObject(newParams);
        var newArguments = [upperParams];
        OpenLayers.Layer.HTTPRequest.prototype.mergeNewParams.apply(this, 
                                                                 newArguments);
    },

    /**
     * APIMethod: clone
     *
     * Parameters:
     * obj - {Object} 
     * 
     * Returns:
     * {<OpenLayers.Layer.WFS>} An exact clone of this OpenLayers.Layer.WFS
     */
    clone: function (obj) {
        
        if (obj == null) {
            obj = new OpenLayers.Layer.WFS(this.name,
                                           this.url,
                                           this.params,
                                           this.options);
        }

        //get all additions from superclasses
        if (this.vectorMode) {
            obj = OpenLayers.Layer.Vector.prototype.clone.apply(this, [obj]);
        } else {
            obj = OpenLayers.Layer.Markers.prototype.clone.apply(this, [obj]);
        }    

        // copy/set any non-init, non-simple values here

        return obj;
    },

    /** 
     * APIMethod: getFullRequestString
     * combine the layer's url with its params and these newParams. 
     *   
     *    Add the SRS parameter from 'projection' -- this is probably
     *     more eloquently done via a setProjection() method, but this 
     *     works for now and always.
     *
     * Parameters:
     * newParams - {Object} 
     */
    getFullRequestString:function(newParams) {
        var projection = this.map.getProjection();
        this.params.SRS = (projection == "none") ? null : projection;

        return OpenLayers.Layer.Grid.prototype.getFullRequestString.apply(
                                                    this, arguments);
    },
   
    /**
     * APIMethod: commit
     * Write out the data to a WFS server.
     */
    commit: function() {
        if (!this.writer) {
            this.writer = new OpenLayers.Format.WFS({},this);
        }

        var data = this.writer.write(this.features);
        
        var url = this.url;
        if (OpenLayers.ProxyHost &&
            OpenLayers.String.startsWith(this.url, "http")) {
            url = OpenLayers.ProxyHost + escape(this.url);
        }

        var success = OpenLayers.Function.bind(this.commitSuccess, this);

        var failure = OpenLayers.Function.bind(this.commitFailure, this);
        
        data = OpenLayers.Ajax.serializeXMLToString(data);
        
        // from prototype.js
        new OpenLayers.Ajax.Request(url, 
                         {   method: 'post', 
                             postBody: data,
                             onComplete: success, 
                             onFailure: failure
                          }
                         );
    },

    /**
     * Method: commitSuccess
     * Called when the Ajax request returns a response
     *
     * Parameters:
     * response - {XmlNode} from server
     */
    commitSuccess: function(request) {
        var response = request.responseText;
        if (response.indexOf('SUCCESS') != -1) {
            this.commitReport('WFS Transaction: SUCCESS', response);
            
            for(var i = 0; i < this.features.length; i++) {
                this.features[i].state = null;
            }    
            // TBD redraw the layer or reset the state of features
            // foreach features: set state to null
        } else if (response.indexOf('FAILED') != -1 ||
            response.indexOf('Exception') != -1) {
            this.commitReport('WFS Transaction: FAILED', response);
        }
    },
    
    /**
     * Method: commitFailure
     * Called when the Ajax request fails
     *
     * Parameters:
     * response - {XmlNode} from server
     */
    commitFailure: function(request) {},
    
    /**
     * APIMethod: commitReport 
     * Called with a 'success' message if the commit succeeded, otherwise
     *     a failure message, and the full request text as a second parameter.
     *     Override this function to provide custom transaction reporting.
     *
     * string - {String} reporting string
     * response - {String} full XML response
     */
    commitReport: function(string, response) {
        alert(string);
    },

    
    /**
     * APIMethod: refresh
     * Refreshes all the features of the layer
     */
    refresh: function() {
        if (this.tile) {
            if (this.vectorMode) {
                this.renderer.clear();
                this.features.length = 0;
            } else {   
                this.clearMarkers();
                this.markers.length = 0;
            }    
            this.tile.draw();
        }
    },

    CLASS_NAME: "OpenLayers.Layer.WFS"
});