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/
原文及代码下载地址:http://jquery-easyui.wikidot.com/tutorial:tree2