ement = document.createElement('div');
            measureTooltipElement.className = 'tooltip tooltip-measure';
            measureTooltip = new ol.Overlay({
                element: measureTooltipElement,
                offset: [0, -15],
                positioning: 'bottom-center'
            });
            map.addOverlay(measureTooltip);
            overLayerList.push(measureTooltip)
        }
        
        /**
        *清空测量工具所有的提示信息
        */
        function removeToolti