GeoServer配置图层按比例尺显示和隐藏

本文介绍如何在GeoServer中发布的图层如WMS图层按比例尺进行显示或隐藏，以及根据这个特性扩展进行不同比例尺下显示不用的样式的设置方法。

一、按比例尺进行显示或隐藏

GeoServer在发布图层的时候，没有直接的选项进行设置在哪个比例尺内可见。但可以通过样式文件进行配置。在样式文件sld（Styled Layer Descriptor）中通过相下面的节点进行配置：

<sld:MinScaleDenominator>1000</sld:MinScaleDenominator> 
<sld:MaxScaleDenominator>6000</sld:MaxScaleDenominator>

以上表示在比例尺为1000-6000范围时显示图层。

下面贴出一个完整的点在一定比例尺内可显示的配置示例：

<?xml version="1.0" encoding="UTF-8"?>
<sld:StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:sld="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml" version="1.0.0">
<sld:UserLayer>
<sld:LayerFeatureConstraints>
<sld:FeatureTypeConstraint/>
</sld:LayerFeatureConstraints>
<sld:UserStyle>
<sld:Name>Default Styler</sld:Name>
<sld:IsDefault>1</sld:IsDefault>
<sld:FeatureTypeStyle>
<sld:Name>simple</sld:Name>
<sld:FeatureTypeName>Feature</sld:FeatureTypeName>
<sld:SemanticTypeIdentifier>generic:geometry</sld:SemanticTypeIdentifier>
<sld:SemanticTypeIdentifier>simple</sld:SemanticTypeIdentifier>
<sld:Rule>
<span style="color:#ff0000;">                    <sld:MinScaleDenominator>3000</sld:MinScaleDenominator>
<sld:MaxScaleDenominator>6000</sld:MaxScaleDenominator> </span>
<sld:PointSymbolizer>
<sld:Geometry>
<ogc:PropertyName>SHAPE</ogc:PropertyName>
</sld:Geometry>
<sld:Graphic>
<sld:Mark>
<sld:WellKnownName>circle</sld:WellKnownName>
<sld:Fill>
<sld:CssParameter name="fill">#90FF90</sld:CssParameter>
</sld:Fill>
<sld:Stroke>
<sld:CssParameter name="stroke">#00FF00</sld:CssParameter>
</sld:Stroke>
</sld:Mark>
<sld:Size>5.0</sld:Size>
</sld:Graphic>
</sld:PointSymbolizer>
</sld:Rule>
</sld:FeatureTypeStyle>
</sld:UserStyle>
</sld:UserLayer>
</sld:StyledLayerDescriptor>

一、图层在不同比例尺下显示不用的样式

基于这种思想我们可以实现不同比例尺显示不同样式。

1、创建多个样式，样式根据需要显示不同比例尺级别来设置，并设置显示比例尺。

2、创建多个图层，分别选择上一步设置的不同样式。

3、创建一个图层组，将上一步创建的图层加入到图层组中。

4、前端调用加载上一步创建发布的图层组。

另外，还有另外一种增加规则标签的实现方法（http://blog.csdn.net/longshengguoji/article/details/51540312）：

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<?xml version="1.0" encoding="ISO-8859-1"?>  

<sld:StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:sld="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:gml="http://www.opengis.net/gml" version="1.0.0">  

    <sld:UserLayer>  

        <sld:LayerFeatureConstraints>  

            <sld:FeatureTypeConstraint/>  

        </sld:LayerFeatureConstraints>  

        <sld:UserStyle>  

            <sld:Name>dianstyle</sld:Name>  

            <sld:Title/>  

            <sld:FeatureTypeStyle>  

                <sld:Name>group 0</sld:Name>  

                <sld:FeatureTypeName>Feature</sld:FeatureTypeName>  

                <sld:SemanticTypeIdentifier>generic:geometry</sld:SemanticTypeIdentifier>  

                <sld:SemanticTypeIdentifier>colorbrewer:unique:paired</sld:SemanticTypeIdentifier>  

                <sld:Rule>  

                    <sld:Name>电梯口big</sld:Name>  

                    <sld:Title>diantikou1</sld:Title>                                

                    <ogc:Filter>  

                        <ogc:PropertyIsEqualTo>  

                                <ogc:PropertyName>type</ogc:PropertyName>  

                                <ogc:Literal>1</ogc:Literal>  

                        </ogc:PropertyIsEqualTo>                              

                    </ogc:Filter>  

                    <sld:MaxScaleDenominator>200.0</sld:MaxScaleDenominator>           

                    <sld:PointSymbolizer>  

                        <sld:Graphic>  

                            <sld:ExternalGraphic>  

                              <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="dianti.png"/>  

                                <sld:Format>image/png</sld:Format>  

                            </sld:ExternalGraphic>  

                            <sld:Size>32</sld:Size>  

                        </sld:Graphic>  

                    </sld:PointSymbolizer>  

                </sld:Rule>  

                <sld:Rule>  

                    <sld:Name>电梯口mediam</sld:Name>  

                    <sld:Title>diantikou2</sld:Title>                                          

                    <ogc:Filter>  

                        <ogc:PropertyIsEqualTo>  

                                <ogc:PropertyName>type</ogc:PropertyName>  

                                <ogc:Literal>1</ogc:Literal>  

                        </ogc:PropertyIsEqualTo>                              

                    </ogc:Filter>  

                    <sld:MinScaleDenominator>200.0</sld:MinScaleDenominator>  

                    <sld:MaxScaleDenominator>400.0</sld:MaxScaleDenominator>       

                    <sld:PointSymbolizer>  

                        <sld:Graphic>  

                            <sld:ExternalGraphic>  

                              <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="dianti.png"/>  

                                <sld:Format>image/png</sld:Format>  

                            </sld:ExternalGraphic>  

                            <sld:Size>26</sld:Size>  

                        </sld:Graphic>  

                    </sld:PointSymbolizer>  

                </sld:Rule>  

                <sld:Rule>  

                    <sld:Name>电梯口small</sld:Name>  

                    <sld:Title>diantikou3</sld:Title>                             

                    <ogc:Filter>  

                        <ogc:PropertyIsEqualTo>  

                                <ogc:PropertyName>type</ogc:PropertyName>  

                                <ogc:Literal>1</ogc:Literal>  

                        </ogc:PropertyIsEqualTo>                              

                    </ogc:Filter>  

                     <sld:MinScaleDenominator>600.0</sld:MinScaleDenominator>    

                    <sld:PointSymbolizer>  

                        <sld:Graphic>  

                            <sld:ExternalGraphic>  

                              <sld:OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="dianti.png"/>  

                                <sld:Format>image/png</sld:Format>  

                            </sld:ExternalGraphic>  

                            <sld:Size>20</sld:Size>  

                        </sld:Graphic>  

                    </sld:PointSymbolizer>  

                </sld:Rule>               

           </sld:FeatureTypeStyle>  

        </sld:UserStyle>  

    </sld:UserLayer>  

</sld:StyledLayerDescriptor>