級聯選單(Mysql實現)
阿新 • • 發佈：2019-01-12
功能描述
- 實際上級聯選單可能在很多情況下出現,例如:在設定地址的時候後,由使用者先設定省份,而後再根據省份生出對應的城市資訊.
- 實現無限極力按選單選擇
- 例如有使用者自己設定要生成幾級選單
資料庫設計
-- 刪除原有的資料表
DROP TABLE IF EXISTS menu;
-- 建立新的資料表
CREATE TABLE menu(
mid INT AUTO_INCREMENT,
title VARCHAR(200),
fmid INT,
CONSTRAINT pk_mid2 PRIMARY KEY(mid),
CONSTRAINT - 無線級別的選單的處理,關鍵體現在這個父的選單項上,但是雖然資料庫是無限的,但是絕不可能在程式中實現無限.
- 在這種情況下要想實現資訊的操作,唯一的用法只能夠通過過Ajax非同步處理操作完成.
後臺業務實現
- 定義Menu,java程式類
package mao.shu.vo;
import java.io.Serializable;
public class Menu implements Serializable {
private String mid;
private String title;
//表示父選單
private Menu fmenu;
public String getMid() {
return mid;
}
public void setMid(String mid) {
this.mid = mid;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Menu getFmenu() {
return fmenu;
}
public void setFmenu(Menu fmenu) {
this.fmenu = fmenu;
}
}
- 定義ImemberDAO.java程式類
package mao.shu.dao;
import mao.shu.vo.Menu;
import java.util.List;
public interface IMenuDAO {
/**
* 列出所有1級選單,列出的所有1級選單中fmenu一定為null
* @return
*/
public List<Menu> findAll();
/**
*根據父選單id,列出此id下的所有子選單
* @return
*/
public List<Menu> findAllSub(String fmid);
}
- 定義MenuDAOImple.java程式類
package mao.shu.dao.imple;
import mao.shu.dao.IMenuDAO;
import mao.shu.vo.Menu;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
public class MenuDAOImpl implements IMenuDAO {
private Connection conn;
private PreparedStatement pstm;
public MenuDAOImpl(Connection conn){
this.conn = conn;
}
@Override
public List<Menu> findAll()throws SQLException {
List<Menu> menus = new ArrayList<Menu>();
String sql = "SELECT mid,title FROM menu WHILE fmid IS NOLL";
this.pstm = this.conn.prepareStatement(sql);
ResultSet rest = this.pstm.executeQuery();
while(rest.next()){
Menu vo = new Menu();
vo.setMid(rest.getString(1));
vo.setTitle(rest.getString(2));
menus.add(vo);
}
return menus;
}
@Override
public List<Menu> findAllSub(String fmid) throws SQLException{
List<Menu> menus = new ArrayList<Menu>();
String sql = "SELECT mid,title FROM menu WHILE fmid=?";
this.pstm = this.conn.prepareStatement(sql);
this.pstm.setString(1,fmid);
ResultSet rest = this.pstm.executeQuery();
while(rest.next()){
Menu vo = new Menu();
vo.setMid(rest.getString(1));
vo.setTitle(rest.getString(2));
menus.add(vo);
}
return menus;
}
}
- 定義DAOFactory.java類,DAO工廠類用於建立DAO介面子類物件
package mao.shu.factory;
import mao.shu.dao.IMemberDAO;
import mao.shu.dao.IMenuDAO;
import mao.shu.dao.imple.MemberDAOImpl;
import mao.shu.dao.imple.MenuDAOImpl;
import java.sql.Connection;
public class DAOFactory {
public static IMemberDAO newMemberDAO(Connection conn){
return new MemberDAOImpl(conn);
}
public static IMenuDAO getMenuDAO(Connection conn){
return new MenuDAOImpl(conn);
}
}
- 在IMenuService介面中定義兩個方法,也是列出一級選單和二級選單
package mao.shu.service;
import mao.shu.vo.Menu;
import java.util.List;
public interface IMenuService {
public List<Menu> findAll()throws Exception;
public List<Menu> findAllSub(String fmid)throws Exception;
}
- 定義MenuServiceImpl.java類
package mao.shu.service.impl;
import mao.shu.dao.IMenuDAO;
import mao.shu.dbc.DatabaseConnection;
import mao.shu.factory.DAOFactory;
import mao.shu.service.IMenuService;
import mao.shu.vo.Menu;
import java.util.List;
public class MenuServiceImpl implements IMenuService {
private DatabaseConnection dataConn = new DatabaseConnection();
@Override
public List<Menu> findAll() throws Exception {
try{
return DAOFactory.getMenuDAO(dataConn.getConnection()).findAll();
}catch(Exception e){
e.printStackTrace();
}finally{
dataConn.getConnection().close();
}
return null;
}
@Override
public List<Menu> findAllSub(String fmid) throws Exception {
try{
return DAOFactory.getMenuDAO(dataConn.getConnection()).findAllSub(fmid);
}catch(Exception e){
e.printStackTrace();
}finally{
dataConn.getConnection().close();
}
return null;
}
}
- 定義ServiceFactory.java程式類
package mao.shu.factory;
import mao.shu.service.IMemberService;
import mao.shu.service.IMenuService;
import mao.shu.service.impl.MemberServiceImpl;
import mao.shu.service.impl.MenuServiceImpl;
public class ServiceFactory {
public static IMemberService getMemberService(){
return new MemberServiceImpl();
}
public static IMenuService getMenuService(){
return new MenuServiceImpl();
}
}
控制層實現
- 本次的操作將採用全部的一步的通訊形式.所以對於Servlet程式而言,可以將資料裝換為XML格式.
- 使用DOM4j開發包操作XML
- 如果最終Servlet生成資料為XML格式,必須將MIME型別設定為xml
- 再生成xml元素的時候,建議資料都已元素的形式出現
- 建立MenuServlet.java程式類
package mao.shu.servlet;
import mao.shu.factory.ServiceFactory;
import mao.shu.vo.Menu;
import org.dom4j.*;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.XMLWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.Iterator;
import java.util.List;
@WebServlet("/MenuServlet/*")
public class MenuServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf-8");
resp.setCharacterEncoding("utf-8");
String uri = req.getRequestURI();
String status = uri.substring(uri.lastIndexOf("/")+1);
if(status != null){
try {
Method method = this.getClass().getMethod(status,HttpServletRequest.class,HttpServletResponse.class);
method.invoke(this,req,resp);
} catch (Exception e) {
e.printStackTrace();
}
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
this.doPost(req, resp);
}
public void listSub(HttpServletRequest req, HttpServletResponse resp) {
resp.setContentType("text/xml");
int fmid = Integer.parseInt(req.getParameter("fmid"));
try {
List<Menu> all = ServiceFactory.getMenuService().findAllSub(fmid);
Document document = DocumentHelper.createDocument();
Element menus = document.addElement("menus");
Iterator<Menu> iterator = all.iterator();
while(iterator.hasNext()){
Menu vo = iterator.next();
Element menu = menus.addElement("menu");
Element mid = menu.addElement("mid");
Element title = menu.addElement("title");
mid.addText(String.valueOf(vo.getMid()));
title.addText(vo.getTitle());
}
OutputFormat outputFormat = OutputFormat.createPrettyPrint();
outputFormat.setEncoding("utf-8");
XMLWriter xmlWriter = new XMLWriter(resp.getWriter());
xmlWriter.write(document);
} catch (Exception e) {
e.printStackTrace();
}
}
public void listAll(HttpServletRequest req