解析无限级树结构，加载dhtmlxTree数据

        dhtmlx组件是一个JavaScript 库，提供了一套完整的Ajax驱动的UI 组件。使用 dhtmlxSuite 生成企业级 web 应用程序有干净的界面、 快速的性能和丰富的用户体验。
dhtmlx组件是由位于俄罗斯圣彼得堡的DHTMLX公司开发的，适用于B/S模式的Web应用开发。

        dhtmlx是一个比较成熟全面的前端控件，比如dhtmlxCombo、dhtmlxEdito、dhtmlxMenu、dhtmlxTabBar、dhtmlxToolbar、dhtmlxTree、dthtmlxFrom、dhtmlxGrid、dhtmlxWindows和dhtmlxLayout等一些控件。其中dhtmlxForm又包含了很多小控件，例如：dhtmlxEditor(富文本编辑器)、dhtmlxCalendar(日期控件)等等。这里就不一一列举。

        下面是我做的一个简单例子，项目的数据持久层使用DBUtils框架实现，action使用dom4j转成文档，DBUtils是一个非常轻量级的数据持久层框架

1、实体类

package com.company.project.entity;
import javax.persistence.Entity;
public class Department {
private int id;  //ID
private String dpname;  // 部门名称
private int parentid;  // 父节点ID

//省略get、set方法

}

2、数据持久层接口

package com.company.project.dao;
import java.util.List;
import com.company.project.entity.Department;
public interface DepartmentDao {
List<Department> selectListDepartments();
}

3、数据持久层实现类

package com.company.project.dao.impl;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import javax.sql.DataSource;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import com.company.project.dao.DepartmentDao;
import com.company.project.entity.Department;
public class DepartmentDaoImpl implements DepartmentDao{
@Override
public List<Department> selectListDepartments() {
List<Department> list = new ArrayList<Department>();
queryRunner = new QueryRunner(ds);
String sql = "select * from Department";
try {
list = queryRunner.query(sql, new BeanListHandler<Department>(Department.class));
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}
private DataSource ds;
private QueryRunner queryRunner;

//省略get、set方法

}

4、业务逻辑层接口

package com.company.project.service;
import java.util.List;
import com.company.project.entity.Department;
public interface DepartmentService {
/**
* 拼装xml树结构字符串
* 
* @return
*/
String selectListTreeDepartments();
}

5、业务逻辑层实现类

package com.company.project.service.impl;
import java.util.ArrayList;
import java.util.List;
import com.company.project.dao.DepartmentDao;
import com.company.project.entity.Department;
import com.company.project.service.DepartmentService;
import com.company.project.strenum.Enum;
public class DepartmentServiceImpl implements DepartmentService {
@Override
public String selectListTreeDepartments() {
// 获取所有的部门
List<Department> list = departmentDao.selectListDepartments();
String str = ForeachXml(list);
return str;
}
/**
* 拼装xml树结构字符串
* 
* @param list
* @return
*/
public String ForeachXml(List<Department> list) {
String xml = "";
StringBuffer buffer = new StringBuffer(
"<?xml version='1.0' encoding='iso-8859-1'?><tree id='0'>");

if (list != null && list.size() > 0) {
for (int i = 0; i < list.size(); i++) {
Department department = list.get(i);
if (department.getParentid() == 0) {

//调用拼接子节点函数
StringBuffer sgBuffer = getXmlBuffer(list, department);
buffer.append(
"<item text='"
+ department.getDpname()
+ "' id='"
+ department.getId()
+ "' open='1' im0='iconTexts.gif' im1='folderOpen.gif' im2='folderClosed.gif'  call='1'>")
.append(sgBuffer).append("</item>");
}
}

}
buffer.append("</tree>");
xml = buffer.toString();
return xml;
}
/**
* 子节点数据拼接xml格式字符
* 
* @param list
* @param dp
* @return
*/
public StringBuffer getXmlBuffer(List<Department> list, Department dp) {
List<Department> ltus = new ArrayList<Department>();
for (int j = 0; j < list.size(); j++) {
Department dt = list.get(j);
if (dt.getParentid() == dp.getId()) {
ltus.add(dt);
}
}
StringBuffer buffer = new StringBuffer();
if (ltus != null && ltus.size() > 0) {
for (int i = 0; i < ltus.size(); i++) {
Department dt = ltus.get(i);

// 递归
StringBuffer sgBuffer = getXmlBuffer(list, dt);
if (sgBuffer.length() > 0) {
buffer.append(
"<item text='"
+ dt.getDpname()
+ "' id='"
+ dt.getId()
+ "' im0='iconTexts.gif' im1='folderOpen.gif' im2='folderClosed.gif'>")
.append(sgBuffer).append("</item>");
} else {
buffer.append("<item text='"
+ dt.getDpname()
+ "' id='"
+ dt.getId()
+ "' im0='iconTexts.gif' im1='folderOpen.gif' im2='folderClosed.gif'/>");
}
}
}
return buffer;
}
private DepartmentDao departmentDao;

//省略get、set方法

}

5、Action

package com.company.project.action;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts2.ServletActionContext;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.DocumentHelper;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;

import com.company.project.service.DepartmentService;

public class DepartmentAction {

/**
* 生成XML格式数据
* 
* @return
*/
public String testTree() {
HttpServletResponse response = ServletActionContext.getResponse();
response.setContentType("text/xml;charset=UTF-8");
response.setHeader("cache-control", "no-cache");
String xml = departmentService.selectListTreeDepartments();
PrintWriter out = null;
try {
out = response.getWriter();
} catch (IOException e2) {
e2.printStackTrace();
}
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("GBK");
XMLWriter writer = new XMLWriter(out, format);
try {
Document document = DocumentHelper.parseText(xml);
writer.write(document);
} catch (IOException e1) {
e1.printStackTrace();
} catch (DocumentException e) {
e.printStackTrace();
}
out.flush();
out.close();
return null;
}
private DepartmentService departmentService;
public DepartmentService getDepartmentService() {
return departmentService;
}
public void setDepartmentService(DepartmentService departmentService) {
this.departmentService = departmentService;
}
}

dhtmlx控件都是异步加载数据，只需要把action的地址赋值给dhtmlxTree控件的loadXML方法