extjs 跨域问题

 items.push({
    xtype: "grid",
    ref: "capsGrid", // makes the grid available as app.capsGrid
    title: "Available Layers",
    region: "north",
    height: 150,
    viewConfig: {forceFit: true},
    store: new GeoExt.data.WMSCapabilitiesStore({
        url: "http://localhost:8090/geoserver/wms?SERVICE=WMS&REQUEST=GetCapabilities&VERSION=1.1.1",
        autoLoad: true
    }),
    columns: [
        {header: "Name", dataIndex: "name", sortable: true},
        {header: "Title", dataIndex: "title", sortable: true},
        {header: "Abstract", dataIndex: "abstract"}
    ]
}); 

在吗这个url跨域了怎么写才行啊