我正在通过扩展 DefaultTreeModel 来研究 zk 树。它在网页上正确呈现。但是当我尝试使用 root 获取与这棵树关联的模型时，我得到了空值。
我正在使用两种方法来做到这一点。1.使用Tree hierarchyTree；hierarchyTree.getModel().getRoot(); // 返回 null 2. 使用 AdvancedTreeModel contactTreeModel 扩展 DefaultTreeModel; ContactTreeNode nodes2 = (ContactTreeNode) contactTreeModel.getRoot(); //也返回null
你能否请告诉我如何获取根节点或与之关联的模型，它不为空。这样我就可以迭代它。
AdvanceTeeModel.java
package demo.tree.dynamic_tree;
import org.zkoss.zul.DefaultTreeModel;
import org.zkoss.zul.DefaultTreeNode;
import demo.data.pojo.Contact;
public class AdvancedTreeModel extends DefaultTreeModel<Contact> {
private static final long serialVersionUID = -5513180500300189445L;
DefaultTreeNode<Contact> _root;
public AdvancedTreeModel(ContactTreeNode contactTreeNode) {
super(contactTreeNode);
_root = contactTreeNode;
}
/**
* remove the nodes which parent is <code>parent</code> with indexes
* <code>indexes</code>
*
* @param parent
* The parent of nodes are removed
* @param indexFrom
* the lower index of the change range
* @param indexTo
* the upper index of the change range
* @throws IndexOutOfBoundsException
* - indexFrom < 0 or indexTo > number of parent's children
*/
public void remove(DefaultTreeNode<Contact> parent, int indexFrom, int indexTo) throws IndexOutOfBoundsException {
DefaultTreeNode<Contact> stn = parent;
for (int i = indexTo; i >= indexFrom; i--)
try {
stn.getChildren().remove(i);
} catch (Exception exp) {
exp.printStackTrace();
}
}
public void remove(DefaultTreeNode<Contact> target) throws IndexOutOfBoundsException {
int index = 0;
DefaultTreeNode<Contact> parent = null;
// find the parent and index of target
parent = dfSearchParent(_root, target);
if(parent!=null){
for (index = 0; index < parent.getChildCount(); index++) {
if (parent.getChildAt(index).equals(target)) {
break;
}
}
remove(parent, index, index);
}
}
/**
* insert new nodes which parent is <code>parent</code> with indexes
* <code>indexes</code> by new nodes <code>newNodes</code>
*
* @param parent
* The parent of nodes are inserted
* @param indexFrom
* the lower index of the change range
* @param indexTo
* the upper index of the change range
* @param newNodes
* New nodes which are inserted
* @throws IndexOutOfBoundsException
* - indexFrom < 0 or indexTo > number of parent's children
*/
public void insert(DefaultTreeNode<Contact> parent, int indexFrom, int indexTo, DefaultTreeNode<Contact>[] newNodes)
throws IndexOutOfBoundsException {
DefaultTreeNode<Contact> stn = parent;
for (int i = indexFrom; i <= indexTo; i++) {
try {
stn.getChildren().add(i, newNodes[i - indexFrom]);
} catch (Exception exp) {
throw new IndexOutOfBoundsException("Out of bound: " + i + " while size=" + stn.getChildren().size());
}
}
}
/**
* append new nodes which parent is <code>parent</code> by new nodes
* <code>newNodes</code>
*
* @param parent
* The parent of nodes are appended
* @param newNodes
* New nodes which are appended
*/
public void add(DefaultTreeNode<Contact> parent, DefaultTreeNode<Contact>[] newNodes) {
DefaultTreeNode<Contact> stn = (DefaultTreeNode<Contact>) parent;
for (int i = 0; i < newNodes.length; i++)
stn.getChildren().add(newNodes[i]);
}
private DefaultTreeNode<Contact> dfSearchParent(DefaultTreeNode<Contact> node, DefaultTreeNode<Contact> target) {
if (node.getChildren() != null && node.getChildren().contains(target)) {
return node;
} else {
int size = getChildCount(node);
for (int i = 0; i < size; i++) {
DefaultTreeNode<Contact> parent = dfSearchParent((DefaultTreeNode<Contact>) getChild(node, i), target);
if (parent != null) {
return parent;
}
}
}
return null;
}
}
实际上我正在使用这个例子，[http://www.zkoss.org/zkdemo/tree/dynamic_tree][来自ZK的动态树]
在 Composer 的覆盖渲染方法中，我使用以下代码行从树中获取根/模型。
ContactTreeNode nodes = (ContactTreeNode) hierarchyTree.getModel().getRoot();
System.out.println("nodes: " + nodes);
ContactTreeNode nodes2 = (ContactTreeNode) contactTreeModel.getRoot();