过了一会儿,我终于明白了。我最终创建了自己的RPC,它将提供一个字符串数组,用于表示下一级别的所有TreeNode的名称。
所以入口点是:
private NodeServiceAsync nodesRpc; //The RPC that grabs more nodes
private Tree data; //The data structure to hold all of the nodes
private ColumnTree list; //The GUI element that is shown on in the browser
public void onModuleLoad() {
nodesRpc = (NodeServiceAsync) GWT.create(NodeService.class);
data = new Tree();
list = new ColumnTree;
list.setAutoFetchData(true);
list.setLoadDataOnDemand(true);
list.addNodeSelectedHandler(new NodeSelectedHandler() {
public void onNodeSelected(NodeSelectedEvent event) {
if(/*Node is folder and hasn't been opened before*/) {
//Get More Nodes
AsyncCallback<String[]> callback = new NodeGetter<String[]>();
nodesRpc.getData(event.getNode(), callback);
}
else if(/*Node is not a folder (at the end) */) {
//Do something else
}
}
});
list.setData(data); //Make the GUI Element Represent The Data Structure
RootPanel.get().add(list); //Add to screen
}
在服务器侧的serverlet创建查询,执行,然后转换该结果集成一个字符串数组并传递回来。所有的回调都需要做,回到客户端,将该数组翻译成TreeNodes数组,并将它们附加到被单击的原始节点上。最后,在所有这些GUI元素都重新绘制新节点。
我很惊讶节点负载(小于1秒)之间的停机时间非常短,即使有时会有一百多个节点被查询然后显示。