Openlayers加载wms.docx
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Openlayers加载wms
OpenLayers的资料，网上已经有很多例子了。
我这里想说的是如何高效的使用OpenLayers。
我们在访问WMS的时候，一般不会只请求一个图层，有可能会是很多图层。
我刚开始使用OpenLayers的时候，是这样使用的：
viewplaincopytoclipboardprint?
varmap,layer;
functioninit（）{
map=newOpenLayers.Map（'map'）;
map.addControl（newOpenLayers.Control.LayerSwitcher（））;
varbounds=newOpenLayers.Bounds（103.94971885,30.5749127,104.18353815,30.7504793）;
layerblock=newOpenLayers.Layer.WMS（"topp:
Block_region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Block_region',
srs:
'EPSG:
4326',
style:
'',
format:
'image/png',
tiled:
'true'
//transparent:
false
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
layerpublic=newOpenLayers.Layer.WMS（"topp:
PUBLIC_region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
PUBLIC_region',
srs:
'EPSG:
4326',
style:
'',
//format:
'image/png',
tiled:
'true',
transparent:
true
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
layerroad=newOpenLayers.Layer.WMS（"topp:
Road_Regular_polyline",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Road_Regular_polyline',
srs:
'EPSG:
4326',
style:
'',
//format:
'image/png',
tiled:
'true',
transparent:
true
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
map.addLayers（[layerblock,layerpublic,layerroad]）;
map.zoomToExtent（bounds）;
}
varmap,layer;
functioninit（）{
map=newOpenLayers.Map（'map'）;
map.addControl（newOpenLayers.Control.LayerSwitcher（））;
varbounds=newOpenLayers.Bounds（103.94971885,30.5749127,104.18353815,30.7504793）;
layerblock=newOpenLayers.Layer.WMS（"topp:
Block_region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Block_region',
srs:
'EPSG:
4326',
style:
'',
format:
'image/png',
tiled:
'true'
//transparent:
false
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
layerpublic=newOpenLayers.Layer.WMS（"topp:
PUBLIC_region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
PUBLIC_region',
srs:
'EPSG:
4326',
style:
'',
//format:
'image/png',
tiled:
'true',
transparent:
true
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
layerroad=newOpenLayers.Layer.WMS（"topp:
Road_Regular_polyline",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Road_Regular_polyline',
srs:
'EPSG:
4326',
style:
'',
//format:
'image/png',
tiled:
'true',
transparent:
true
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.8,
isBaseLayer:
true
}
）;
map.addLayers（[layerblock,layerpublic,layerroad]）;
map.zoomToExtent（bounds）;
}
viewplaincopytoclipboardprint?
但是，我发现这样访问的速度极其的慢。
然后，又把这个例子改造成以下的样子，发现，速度提高很多。
但是，我发现这样访问的速度极其的慢。
然后，又把这个例子改造成以下的样子，发现，速度提高很多。
viewplaincopytoclipboardprint?
varmap,layer;
functioninit（）{
map=newOpenLayers.Map（'map'）;
map.addControl（newOpenLayers.Control.LayerSwitcher（））;
varbounds=newOpenLayers.Bounds（103.94971885,30.5749127,104.18353815,30.7504793）;
layerpublic=newOpenLayers.Layer.WMS（"region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Block_region,topp:
PUBLIC_region,topp:
Road_Regular_polyline',
srs:
'EPSG:
4326',
style:
'',
format:
'image/png',
tiled:
'false',
transparent:
false
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.5,
isBaseLayer:
true
}
）;
map.addLayer（layerpublic）;
map.zoomToExtent（bounds）;
}
viewplaincopytoclipboardprint?
varmap,layer;functioninit（）{map=newOpenLayers.Map（'map'）;map.addControl（newOpenLayers.Control.LayerSwitcher（））;varbounds=newOpenLayers.Bounds（103.94971885,30.5749127,104.18353815,30.7504793）;layerpublic=newOpenLayers.Layer.WMS（"region","http:
//localhost:
8989/geoserver/wms",{layers:
'topp:
Block_region,topp:
PUBLIC_region,topp:
Road_Regular_polyline',srs:
'EPSG:
4326',style:
'',format:
'image/png',tiled:
'false',transparent:
false},{maxExtent:
bounds,//maxResolution:
0.0041261434555042165,projection:
'EPSG:
4326',buffer:
0,reproject:
true,//opacity:
0.5,isBaseLayer:
true}）;map.addLayer（layerpublic）;map.zoomToExtent（bounds）;}
varmap,layer;
functioninit（）{
map=newOpenLayers.Map（'map'）;
map.addControl（newOpenLayers.Control.LayerSwitcher（））;
varbounds=newOpenLayers.Bounds（103.94971885,30.5749127,104.18353815,30.7504793）;
layerpublic=newOpenLayers.Layer.WMS（"region",
"http:
//localhost:
8989/geoserver/wms",
{
layers:
'topp:
Block_region,topp:
PUBLIC_region,topp:
Road_Regular_polyline',
srs:
'EPSG:
4326',
style:
'',
format:
'image/png',
tiled:
'false',
transparent:
false
},
{
maxExtent:
bounds,
//maxResolution:
0.0041261434555042165,
projection:
'EPSG:
4326',
buffer:
0,
reproject:
true,
//opacity:
0.5,
isBaseLayer:
true
}
）;
map.addLayer（layerpublic）;
map.zoomToExtent（bounds）;
}
viewplaincopytoclipboardprint?
这样看，就明白了，最上面的是请求了三个WMS服务，下面的只请求了一个WMS服务。
这样看，就明白了，最上面的是请求了三个WMS服务，下面的只请求了一个WMS服务。
viewplaincopytoclipboardprint?
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