name {string} A name for the layer,
url {string} Base url for the WMS(e.g. http://wms.jpl.nasa.gov/wms.cgi)
params {object} An object with key/value parirs representing the GetMap query string parameters and parameter values
oprions {Object} Hashtable of extra options to tag onto the layer. These options include all properties listed above, plus the ones inherited from superclasses.(可省)
var wms =new OpenLayers.Layer.WMS(
"图层名称",
"http://wms.jpl.nasa.gov/wms.cgi",
{layers:"modis,global_mosaic"}
);