jquery-easyui中创建异步加载树

              jquery-easyui中的树可以从标记中建立，也可以通过指定一个URL属性读取数据建立。如果想建立一棵异步树，需要为每个节点指定一个id属性值，这样在加载数据时会自动向后台传递id参数。

 

<ul id="tt"></ul>

编写前台代码：

$('#tt').tree({
    url:'/demo2/node/getNodes'    // The url will be mapped to NodeController class and getNodes method
});

为测试用，建立一个节点的数据模型：

@Table(name="nodes")
public class Node extends ActiveRecordBase{
    @Id public Integer id;
    @Column public Integer parentId;
    @Column public String name;

    public boolean hasChildren() throws Exception{
        long count = count(Node.class, "parentId=?", new Object[]{id});
        return count > 0;
    }
}

编写后台的控制器代码：

public class NodeController extends ApplicationController{
    /**
     * get nodes, if the 'id' parameter equals 0 then load the first level nodes,
     * otherwise load the children nodes
     * @param id the parent node id value
     * @return the tree required node json format
     * @throws Exception
     */
    public View getNodes(int id) throws Exception{
        List<Node> nodes = null;

        if (id == 0){    // return the first level nodes
            nodes = Node.findAll(Node.class, "parentId=0 or parentId is null", null);
        } else {    // return the children nodes
            nodes = Node.findAll(Node.class, "parentId=?", new Object[]{id});
        }

        List<Map<String,Object>> items = new ArrayList<Map<String,Object>>();
        for(Node node: nodes){
            Map<String,Object> item = new HashMap<String,Object>();
            item.put("id", node.id);
            item.put("text", node.name);

            // the node has children,
            // set the state to 'closed' so the node can asynchronous load children nodes
            if (node.hasChildren()){
                item.put("state", "closed");
            }
            items.add(item);
        }

        return new JsonView(items);
    }
}

运行测试程序：http://localhost:8080/demo2/