最近一直在研究这个树形的下拉选择框,感觉非常的有用,现在整理下来供大家使用:
首先数据库的表架构设计和三级菜单联动的表结构是一样,(父子关系)
1、下面我们用hibernate建一下对应的额实体类:
package com.hanqi.entity; //地区 实体类 public class Region { //地区id private String regionID; //地区名称 private String regionName; //上级id private String parentRegionID; public String getRegionID() { return regionID; } public void setRegionID(String regionID) { this.regionID = regionID; } public String getRegionName() { return regionName; } public void setRegionName(String regionName) { this.regionName = regionName; } public String getParentRegionID() { return parentRegionID; } public void setParentRegionID(String parentRegionID) { this.parentRegionID = parentRegionID; } @Override public String toString() { return "Region [regionID=" + regionID + ", regionName=" + regionName + ", parentRegionID=" + parentRegionID + "]"; } }
2、dao层查询数据的方法:
//获取数据列表 public List<Region> getlist(String parentid) { List<Region> rtn=new ArrayList<Region>(); init(); //查询数据 rtn=se.createQuery("from Region where parentRegionID=?").setString(0, parentid).list(); destory(); return rtn; }
3、建立service层的(在这里需要注意的是:返回的JSON格式的数据是一个嵌套的格式,这里就用到了递归的方法即根据父ID查询他的子ID然后再继续查询子ID下面的子ID。。。
返回的数据格式 必须包含 按照id:‘‘,text:‘‘children:[‘{}‘]的格式,所以我们先建一个这种格式的类。从数据库中取出数据后以这种类的格式返回
)
建一个tree需要的格式的类:
package com.hanqi.service; import java.util.List; public class TreeNode { private String id; private String text; private List<TreeNode> children; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getText() { return text; } public void setText(String text) { this.text = text; } public List<TreeNode> getChildren() { return children; } public TreeNode(String id, String text) { super(); this.id = id; this.text = text; } public void setChildren(List<TreeNode> children) { this.children = children; } public TreeNode() { super(); } }
service层里面的调用数据库层数据,采用递归方法循环遍历 子id,当不满足条件时,递归方法跳出,重点理解下面的getTreeNode()方法:
package com.hanqi.service; import java.util.ArrayList; import java.util.List; import com.hanqi.dao.RegionDao; import com.hanqi.entity.Region; public class RegionService { // public List<Region> getList(String parentid) { return new RegionDao().getlist(parentid); } //递归调用的方法 //获取子节点的集合 public List<TreeNode> getTreeNode(String id) { List<TreeNode> rtn =null; List<Region> lr=getList(id); if(lr!=null&&lr.size()>0) { rtn=new ArrayList<>(); for(Region r:lr) { TreeNode tn=new TreeNode(r.getRegionID(), r.getRegionName()); System.out.println("name="+r.getRegionName()); //得到节点的子节点 //递归的调用 List<TreeNode>children= getTreeNode(r.getRegionID()); tn.setChildren(children); rtn.add(tn); } } return rtn; } }
servlet层调用service的数据,并把数据转换成JSON格式返回给前台:
package com.hanqi.web; import java.io.IOException; import java.util.List; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.alibaba.fastjson.JSONArray; import com.hanqi.entity.H_Depart; import com.hanqi.service.RegionService; import com.hanqi.service.TreeNode; /** * Servlet implementation class DepartServlet */ public class DepartServlet extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public DepartServlet() { super(); // TODO Auto-generated constructor stub } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); response.setContentType("text/html"); RegionService rs=new RegionService(); List<TreeNode> lr =rs.getTreeNode("0"); String json=JSONArray.toJSONString(lr); System.out.println(json); response.getWriter().print(json); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }
前段的显示层调用:
部门: <input class="easyui-combotree" id="depart" name="depart" data-options="{url:‘DepartServlet‘}" />
效果:
时间: 2024-11-06 03:44:24