geoserver中webcache的使用

<context-param>
   <param-name>GEOWEBCACHE_CACHE_DIR</param-name>
   <param-value>你的geowebcache切片的目录</param-value>
  </context-param>

<?xml version="1.0" encoding="utf-8"?>
<gwcConfiguration xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns="http://geowebcache.org/schema/1.3.0"
  xsi:schemaLocation="http://geowebcache.org/schema/1.3.0 http://geowebcache.org/schema/1.3.0/geowebcache.xsd">
  <version>1.3.0</version>
  <backendTimeout>120</backendTimeout>
  <serviceInformation>
    <title>GeoWebCache</title>
    <description>GeoWebCache is an advanced tile cache for WMS servers.It supports a large variety of protocols and
      formats, including WMS-C, WMTS, KML, Google Maps and Virtual Earth.</description>
    <keywords>
      <string>WFS</string>
      <string>WMS</string>
      <string>WMTS</string>
      <string>GEOWEBCACHE</string>
    </keywords>
    <serviceProvider>
      <providerName>John Smith inc.</providerName>
      <providerSite>http://www.example.com/</providerSite>
      <serviceContact>
        <individualName>John Smith</individualName>
        <positionName>Geospatial Expert</positionName>
        <addressType>Work</addressType>
        <addressStreet>1 Bumpy St.</addressStreet>
        <addressCity>Hobart</addressCity>
        <addressAdministrativeArea>TAS</addressAdministrativeArea>
        <addressPostalCode>7005</addressPostalCode>
        <addressCountry>Australia</addressCountry>
        <phoneNumber>+61 3 0000 0000</phoneNumber>
        <faxNumber>+61 3 0000 0001</faxNumber>
        <addressEmail>john.smith@example.com</addressEmail>
      </serviceContact>
    </serviceProvider>
    <fees>NONE</fees>
    <accessConstraints>NONE</accessConstraints>
  </serviceInformation>
  
  
<!--下面定义的是瓦片格网的信息，主要配置投影名称，数据框（坐标范围），比例尺集合，瓦片大小，geowebcache会根据这些信息来分割地图-->
  <gridSets>
    <!-- Grid Set Example, by default EPSG:900913 and EPSG:4326 are defined -->
 <gridSet>
    <!--格网信息的名称，这里只是一个标识，可以随便起，下面配置wmsLayer的时候会用到-->
    <name>EPSG:3395</name>
    <!--这里对应的就是真正的投影名称了，要说明的是，geowebcache本身并不认得这些投影名称，因为地图数据是从地图服务器里来的，这些信息最终是要传到地图服务器中去的，所以这里只要和地图服务器中的投影名称一致就可以了-->
    <srs><number>3395</number></srs>
    <!--地图图层的坐标范围，也可以理解为，你需要切图的范围，可以不指定-->
    <extent>
      <coords>
        <double>12063355.362599999</double>
        <double>3248729.1457272936</double>
        <double>13122908.970199998</double>
        <double>3908502.2175705903</double>
      </coords>
    </extent>
    <!--分辨率集合（也就是定义缩放的级别），一个像素点代表多少地图单位，和比例尺的意思一样，这里定义了11个缩放级别-->
    <resolutions>
      <double>1000.4406398437495</double>      
      <double>517.3601599609374</double>      
      <double>258.6800799804687</double>      
      <double>129.34003999023435</double>    
      <double>64.67001999511717</double>      
      <double>32.335009997558586</double>      
      <double>16.167504998779293</double>      
      <double>8.083752499389647</double>      
      <double>4.0104690624237058</double>      
      <double>2.25261726560592646</double>      
      <double>1.12630863280296323</double> 
    </resolutions>  
    <!--字面理解，每个单位所代表的长度-->
    <metersPerUnit>1</metersPerUnit>  
    <pixelSize>0.0002645833333333333333333333</pixelSize>
    <!--瓦片的长宽-->
    <tileHeight>256</tileHeight>
    <tileWidth>256</tileWidth>
  </gridSet>
  </gridSets>

  <layers>    
    <wmsLayer>
    <!--地图名称，这个会在openlayer调用的时候中用到-->
      <name>heightway</name>
      <metaInformation>
        <title>heightway</title>
        <description>heightway</description>
      </metaInformation>
      <!--图片格式-->
      <mimeFormats>
        <string>image/jpeg</string>
      </mimeFormats>
      <!-- 使用的瓦片格网，就是上面所配置的格网信息 -->
      <gridSubsets>
        <gridSubset>
          <gridSetName>EPSG:3395</gridSetName>        
        </gridSubset>
      </gridSubsets>
      <!--wms服务地址-->
      <wmsUrl>
        <string>http://localhost:8006/geoserver/cite/wms?service=WMS</string>
      </wmsUrl>
      <wmsLayers>cite:heightWay</wmsLayers>
      <!--是否透明-->
      <transparent>false</transparent>
      <!--背景色-->
      <bgColor>#FCFCFC</bgColor>
    </wmsLayer>
  </layers>
  
</gwcConfiguration>

 1 var options = 
 2             {
 3                 resolutions:[1.12630863280296323,2.25261726560592646,4.0104690624237058,8.083752499389647,16.167504998779293,32.335009997558586,64.67001999511717,129.34003999023435,258.6800799804687,517.3601599609374,1000.4406398437495],
 4                 projection: new OpenLayers.Projection("EPSG:3395"),
 5                 units: "meters",
 6                 maxExtent: bounds
 7             };
 8 
 9             //初始化地图对象
10             var map = new OpenLayers.Map("GisMap", options);
11             //底图
12             var baseLayer = new OpenLayers.Layer.WMS(
13                 "baseLayer",
14                 "http://localhost:8006/geowebcache/service/wms",
15                 { layers: "heightway", format: ‘image/jpeg‘ },
16                 { tileSize: new OpenLayers.Size(256,256) }
17             );
18     map.addLayers([baseLayer]);