下面的代码定义了一个完整的ext treepanel的实例，其中，对checkchange事件的处理，使单击父亲节点时对下面的子节点全部选中或取消选中。
sysFunClassTree = new Ext.tree.TreePanel({
id:'sysFunClassTree',split:true,collapsible:true,rootVisible:false,name:'sysFunClassTree',autoScroll:true,border:true,
region:'east',title:'功能分类树',width:200,
loader:new Ext.tree.TreeLoader({dataUrl:'http://localhost:8080/jeasyweb/treeSysFunClass.do',baseParams:{'_tree_checkbox':'true'}})
});
sysFunClassTree_root = new Ext.tree.AsyncTreeNode({
text:'Ext TreeRoot',id:'src_root'
});
sysFunClassTree.setRootNode(sysFunClassTree_root);
sysFunClassTree.on('click', function(node, e){treeClick(node, e);});
sysFunClassTree.on('checkchange', function(node, flag) {
if (node.hasChildNodes()) {
node.eachChild(function(child) {
child.ui.toggleCheck(flag);
child.attributes.checked = flag;
child.fireEvent('checkchange', child, flag);
});
}
});