请教树的问题！

[liushuiriji]

想做一个展开的树！
我的servlet只能得到根目录，每次都需点击才能出下一级。求救怎么直接就是展开的树！！！！！！！！！
我的servlet
package com.bgonline.dzsw.util.tree;



/**
* <p>Title: </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2007</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/

import java.sql.ResultSet;

import javax.servlet.ServletException;
import javax.servlet.http.*;

import com.bgonline.common.DBProcessSQL;

public class TreeviewServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = -7497892726836542298L;
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
System.out.println("aaaaaaaaaaaaaaaaaaaa");
String parentID = request.getParameter("parent");//获得id的值
String pagemane = request.getParameter("pagename");//获得页面
System.out.println(parentID);
System.out.println(pagemane);
DbManager dm = new DbManager();

response.setContentType("text/html;charset=GBK");
java.io.PrintWriter out = response.getWriter();
String outputString = "";





if (parentID!=null&&!parentID.equals(""))//如果不为null和空
{
Category category = new Category(parentID, dm);// 创建Category对象
TreeviewElement[] top = category.getChildren(dm, false);// 得到该分类的所有下级分类

for(int i= 0;i<top.length;i++)//循环显示每个分类
outputString = treeviewRender.renderTreeViewAjax(top[i], false,
pagemane, dm);
String subId = SecondTree(parentID);
String[] sub= subId.split(",");
for(int n=0; n<sub.length;n++){
System.out.println(sub[0]);
category = new Category(subId, dm);
outputString = treeviewRender.renderTreeViewAjax(top[n], false,pagemane, dm);
}
}
out.println(outputString);
dm.close();
}

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {

doPost(request, response);
}
String SecondTree(String parentID) {
String aa = "";
String nn = "";
DBProcessSQL dbps = new DBProcessSQL("watchtax");
ResultSet resultSet = null;
String sql = "SELECT * FROM LTXXB where UpLevelID = '" + parentID + "'";
String sqlparam[][] = new String[0][2];
try {
for (resultSet = dbps.query(sql, sqlparam, 0); resultSet.next();) {
aa = resultSet.getString("pk");
nn = aa+","+nn;
String sub[] = nn.split(",");
System.out.println("+++++++=="+sub[0]);
}

System.out.println("=================="+nn);
return aa;
} catch (Exception e) {
e.printStackTrace();
return aa;
}
}
}

[liushuiriji]

我这样写for(int n=0; n <sub.length;n++){
System.out.println(sub[0]);
这个for循环只循环一次

[JackRui2008]

那你检查下
String subId = SecondTree(parentID);
String[] sub= subId.split(",");
这2个值是不是你想要的值。

[liushuiriji]

我检查了！是我想要的值！
for (resultSet = dbps.query(sql, sqlparam, 0); resultSet.next();) {
aa = resultSet.getString("pk");
nn = aa+","+nn;
String sub[] = nn.split(",");
System.out.println("+++++++=="+sub[0]);
}
能得出我要的值

[guodong66]

把整棵树都查询出来，传到表单，然后都显示。

[lixiao1387]

用jquery试试