Struts2中关于s:tree

Struts2中可以通过s:tree标签轻松的实现一个树状结构。

下面是一个s:tree的具体实现的例子。数的结构用mysql数据库类维护。

1.创建数据库表

DROP TABLE IF EXISTS CATEGORY_MASTER ; CREATE TABLE CATEGORY_MASTER( CATEGORY_ID int auto_increment NOT NULL, CATEGORY_NAME varchar(50) NOT NULL, PARENT_CATEGORY_ID int DEFAULT -1 NOT NULL, PRIMARY KEY (CATEGORY_ID) )

 

2.创建数据库连接类

参看 Struts2中DB操作的一个例子(1)

3.创建Category.java，用来保存DB数据和页面提交的数据

package s2.ex.data; public class Category { private int id; private String name; private Category[] children; private int parentNodeId; public Category[] getChildren() { return children; } public void setChildren(Category[] children) { this.children = children; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getParentNodeId() { return parentNodeId; } public void setParentNodeId(int parentNodeId) { this.parentNodeId = parentNodeId; } }

  4.创建对数据库表category_master操作的类

package s2.ex.svc;import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList;import s2.ex.data.Category; import s2.ex.db.DBConn;public class CategoryService { private static CategoryService instance; private CategoryService() { } public static CategoryService getInstance() { if (instance == null){ instance = new CategoryService(); } return instance; } public Category[] getCategoryList() { Connection conn = DBConn.getConnection(); final String SQL = "SELECT * FROM category_master"; ResultSet rs = null; try { rs = conn.createStatement().executeQuery(SQL); ArrayList aryResult = new ArrayList(); while (rs.next()) { Category category = new Category(); category.setId(rs.getInt("CATEGORY_ID")); category.setName(rs.getString("CATEGORY_NAME")); aryResult.add(category); } Category[] result = new Category[aryResult.size()]; result = aryResult.toArray(result); return result; } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rs != null){ rs.close(); } if (conn != null) { if (!conn.isClosed()) { conn.close(); } } } catch (SQLException e) { e.printStackTrace(); } } return null; } public boolean addNewTreeNode(Category category) { Connection conn = DBConn.getConnection(); final String SQL = "INSERT INTO category_master(CATEGORY_NAME,PARENT_CATEGORY_ID) VALUES(?,?)"; PreparedStatement pre = null; try { pre = conn.prepareStatement(SQL); pre.setString(1, category.getName()); pre.setInt(2, category.getParentNodeId()); int result = pre.executeUpdate(); if (result >= 0) { return true; } } catch (SQLException e) { e.printStackTrace(); } finally { try { if (pre != null){ pre.close(); } if (conn != null) { if (!conn.isClosed()) { conn.close(); } } } catch (SQLException e) { e.printStackTrace(); } } return false; } public Category[] getAllCategory() { Connection conn = DBConn.getConnection(); final String SQL = "SELECT * FROM category_master where PARENT_CATEGORY_ID=-1"; ResultSet rs = null; try { rs = conn.createStatement().executeQuery(SQL); ArrayList aryResult = new ArrayList(); while (rs.next()) { Category category = new Category(); category.setId(rs.getInt("CATEGORY_ID")); category.setName(rs.getString("CATEGORY_NAME")); category.setChildren(this.getChildren(category.getId())); aryResult.add(category); } Category[] result = new Category[aryResult.size()]; result = aryResult.toArray(result); return result; } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rs != null){ rs.close(); } if (conn != null) { if (!conn.isClosed()) { conn.close(); } } } catch (SQLException e) { e.printStackTrace(); } } return null; } public Category[] getChildren(int categoryId) { Connection conn = DBConn.getConnection(); final String SQL = "SELECT * FROM category_master where PARENT_CATEGORY_ID=?"; PreparedStatement pre = null; ResultSet rs = null; try { pre = conn.prepareStatement(SQL); pre.setInt(1, categoryId); rs = pre.executeQuery(); ArrayList aryResult = new ArrayList(); while (rs.next()) { Category category = new Category(); category.setId(rs.getInt("CATEGORY_ID")); category.setName(rs.getString("CATEGORY_NAME")); category.setChildren(this.getChildren(category.getId())); aryResult.add(category); } Category[] result = new Category[aryResult.size()]; result = aryResult.toArray(result); return result; } catch (SQLException e) { e.printStackTrace(); } finally { try { if (rs != null){ rs.close(); } if (pre != null){ pre.close(); } if (conn != null) { if (!conn.isClosed()) { conn.close(); } } } catch (SQLException e) { e.printStackTrace(); } } return null; }

  上面getChildren方法里面用到了递归

TreeIndex.jsp TreeEdit.jsp TreeEdit.jsp DisplayTree.action

 

9.通过 http://localhost:8080/s2/test/DisplayTree.action来测试，结果如下

展开后

节点追加

点击一个节点时

5.创建action类

package s2.ex.action;import s2.ex.data.Category; import s2.ex.svc.CategoryService;import com.opensymphony.xwork2.ActionSupport;public class SimpleTreeAction extends ActionSupport {private static final long serialVersionUID = 1L; private Category root; private Category[] parentNodeIds; private Category editCategory; public String displayTree() { root = new Category(); root.setId(-1); root.setName("root"); root.setChildren(CategoryService.getInstance().getAllCategory()); return SUCCESS; } public Category getRoot() { return root; } public void setRoot(Category root) { this.root = root; } public String goTreeEdit(){ this.parentNodeIds = CategoryService.getInstance().getCategoryList(); return SUCCESS; } public Category[] getParentNodeIds() { return parentNodeIds; } public void setParentNodeIds(Category[] parentNodeIds) { this.parentNodeIds = parentNodeIds; } public Category getEditCategory() { return editCategory; } public void setEditCategory(Category editCategory) { this.editCategory = editCategory; } public String saveTreeNode() { if (CategoryService.getInstance().addNewTreeNode(this.editCategory)){ return SUCCESS; }else { return INPUT; } } }

  6.创建TreeIndex.jsp，用来显示树

<%@ page contentType="text/html; charset=UTF-8" %> <%@page pageEncoding="utf-8" %> <%@taglib prefix="s" uri="/struts-tags" %>

7.创建用来增加节点的TreeEdit.jsp<%@ page contentType="text/html; charset=UTF-8" %> <%@page pageEncoding="utf-8" %> <%@taglib prefix="s" uri="/struts-tags" %>

 8.配置struts.xml