JDBC+Servlet+JSP整合開發之31-JSP項目實戰

–編程思想
?分層開發思想
?面向接口編程思想
–設計模式
? DAO設計模式
? MVC設計模式
–實例
?收藏管理

------------------------------Start-----------------------------------

? 編程思想
–分層開發思想
?軟件的層次結構可以分爲四層：
–表現層
–控制層
–業務邏輯層
–數據邏輯層（持久層）
–面向接口編程思想
?在編程中將業務邏輯抽象出接口，以供上次調用
?依賴抽象（接口），而非具體（接口實現）的編程思想，又稱之爲控制反轉（Inversion of Control)

? 設計模式
–DAO設計模式
? DAO的全稱是：Data Access Object，數據訪問對象。
? 使用DAO設計模式，來封裝數據庫持久層的所以操作（CRUD），使低級的數據邏輯和高級的業務邏輯分離，達到解耦合的目的。
–一個典型的DAO實現有如下的組件：
? 一個 DAO 接口
? 一個實現了 DAO 接口的具體類
? 一個 DAO 工廠類
? 數據傳輸對象(有時稱爲值對象)
–以維護一個客戶信息爲例，具體組件如下所示：
? CustomerDao 接口
? Customer 值對象（VO)
? CustomerDaoImpl（接口的具體實現類）
? CustomerFactory（工廠類，實例化用）

? 編程思想和設計模式的具體應用
–圖示

? 實例
–收藏管理
?實例描述
–本實例運用了分層開發思想、面向接口編程兩種思想；和
DAO、MVC設計模式來實現一個收藏管理程序
–程序的主要功能是，把感興趣的鏈接做維護，包括添加一個新
的鏈接、刪除一個鏈接、顯示一個鏈接列表、修改鏈接等內容
?用到的表
–收藏表（LinkTbl)

? 實例
–收藏管理
?程序部分運行結果

LinkDao.java

LinkDaoImpl.java

package com.michael.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import com.michael.dao.LinkDao;
import com.michael.util.ConnectionUtil;
import com.michael.util.SQLConstants;
import com.michael.vo.Link;

public class LinkDaoImpl implements LinkDao,SQLConstants{

        public void add(Link l) {
                Connection conn = new ConnectionUtil().openConnection();
                try {
                        PreparedStatement pstmt = conn.prepareStatement(ADD_LINK_SQL);
                        pstmt.setString(1, l.getName());
                        pstmt.setString(2, l.getUrl());
                        pstmt.executeUpdate();
                } catch (SQLException e) {
                        e.printStackTrace();
                }finally{
                        try {
                                conn.close();
                        } catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
        }

        public void delete(String[] ids) {
                Connection conn = new ConnectionUtil().openConnection();
                try {
                        PreparedStatement pstmt = conn.prepareStatement(DELETE_LINK_SQL);
                        if(ids!=null&&ids.length>0)
                        for(int i=0;i<ids.length;i++){
                                pstmt.setInt(1, Integer.parseInt(ids[i]));
                                pstmt.executeUpdate();
                        }

                } catch (SQLException e) {
                        e.printStackTrace();
                }finally{
                        try {
                                conn.close();
                        } catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
        }

        public Link get(int id) {
                Connection conn = new ConnectionUtil().openConnection();
                try {
                        PreparedStatement pstmt = conn.prepareStatement(GET_LINK_SQL);
                        pstmt.setInt(1, id);
                        ResultSet rs = pstmt.executeQuery();
                        if(rs.next()){
                                //int id = rs.getInt(1);
                                String name = rs.getString(2);
                                String url = rs.getString(3);
                                Link l = new Link();
                                l.setId(id);
                                l.setName(name);
                                l.setUrl(url);
                                return l;
                        }
                } catch (SQLException e) {
                        e.printStackTrace();
                }finally{
                        try {
                                conn.close();
                        } catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
                return null;
        }

        public List list() {
                Connection conn = new ConnectionUtil().openConnection();
                try {
                        Statement stmt = conn.createStatement();
                        ResultSet rs = stmt.executeQuery(QUERY_LINK_SQL);
                        List list = new ArrayList();
                        while(rs.next()){
                                int id = rs.getInt(1);
                                String name = rs.getString(2);
                                String url = rs.getString(3);
                                Link l = new Link();
                                l.setId(id);
                                l.setName(name);
                                l.setUrl(url);
                                list.add(l);
                        }
                        return list;
                } catch (SQLException e) {
                        e.printStackTrace();
                }finally{
                        try {
                                conn.close();
                        } catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
                return null;
        }

        public void update(Link l) {
                Connection conn = new ConnectionUtil().openConnection();
                try {
                        PreparedStatement pstmt = conn.prepareStatement(UPDATE_LINK_SQL);
                        pstmt.setString(1, l.getName());
                        pstmt.setString(2, l.getUrl());
                        pstmt.setInt(3, l.getId());
                        pstmt.executeUpdate();
                } catch (SQLException e) {
                        e.printStackTrace();
                }finally{
                        try {
                                conn.close();
                        } catch (SQLException e) {
                                e.printStackTrace();
                        }
                }
        }

}

LinkServlet.java

package com.michael.servlet;

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.michael.dao.LinkDao;
import com.michael.dao.impl.LinkDaoImpl;
import com.michael.vo.Link;

public class LinkServlet extends HttpServlet {

        /**
         * Constructor of the object.
         */
        public LinkServlet() {
                super();
        }

        /**
         * Destruction of the servlet. <br>
         */
        public void destroy() {
                super.destroy(); // Just puts "destroy" string in log
                // Put your code here
        }

        /**
         * The doGet method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to get.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {

                doPost(request,response);
        }

        /**
         * The doPost method of the servlet. <br>
         *
         * This method is called when a form has its tag value method equals to post.
         *
         * @param request the request send by the client to the server
         * @param response the response send by the server to the client
         * @throws ServletException if an error occurred
         * @throws IOException if an error occurred
         */
        public void doPost(HttpServletRequest request, HttpServletResponse response)
                        throws ServletException, IOException {
                String methodName = request.getParameter("methodName");

                if (methodName != null && methodName.equals("add")) {
                        add(request, response);
                } else if (methodName != null && methodName.equals("query")) {
                        query(request, response);

                } else if (methodName != null && methodName.equals("delete")) {

                        delete(request, response);
                } else if (methodName != null && methodName.equals("forward")) {

                        forward(request, response);
                } else if (methodName != null && methodName.equals("update")) {

                        update(request, response);
                } else {
                        return;
                }
                /*
                //響應用戶請求
                String name = request.getParameter("name");
                String url = request.getParameter("url");
                //調用後臺邏輯
                LinkDao dao = new LinkDaoImpl();
                Link l = new Link();
                l.setName(name);
                l.setUrl(url);
                dao.add(l);
                List list = dao.list();
                request.setAttribute("LinkList", list);
                //轉發
                request.getRequestDispatcher("/link.jsp").forward(request, response);
                */
        }
        public void add(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {

                //響應用戶請求
                String name = request.getParameter("name");
                String url = request.getParameter("url");
                //調用後臺邏輯
                LinkDao dao = new LinkDaoImpl();
                Link l = new Link();
                l.setName(name);
                l.setUrl(url);
                dao.add(l);
                query(request,response);
        }
        public void query(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
                //調用後臺邏輯
                LinkDao dao = new LinkDaoImpl();
                List list = dao.list();
                request.setAttribute("LinkList", list);
                //轉發
                request.getRequestDispatcher("/link.jsp").forward(request, response);
        }
        public void delete(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
                //調用後臺邏輯
                LinkDao dao = new LinkDaoImpl();
                String[] ids = request.getParameterValues("ids");
                dao.delete(ids);
                query(request,response);
        }
        public void forward(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
                //調用後臺邏輯
                String id = request.getParameter("id");
                LinkDao dao = new LinkDaoImpl();
                Link link = dao.get(Integer.parseInt(id));
                request.setAttribute("link", link);
                request.getRequestDispatcher("/editLink.jsp").forward(request, response);
        }
        public void update(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
                //響應用戶請求
                String id = request.getParameter("id");
                String name = request.getParameter("name");
                String url = request.getParameter("url");
                //調用後臺邏輯
                LinkDao dao = new LinkDaoImpl();
                Link l = new Link();
                l.setId(Integer.parseInt(id));
                l.setName(name);
                l.setUrl(url);
                dao.update(l);
                query(request,response);
}

        /**
         * Initialization of the servlet. <br>
         *
         * @throws ServletException if an error occurs
         */
        public void init() throws ServletException {
                // Put your code here
        }

}

ConnectionUtil.java

package com.michael.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

public class ConnectionUtil {

        /**
         * @param args
         */
        public static void main(String[] args) {
                ConnectionUtil cu = new ConnectionUtil();
                System.out.println(cu.openConnection());
        }
        public Connection openConnection() {
                String url = "";
                String driver = "";
                String user = "";
                String password = "";
                Properties prop = new Properties();
                try {
                        prop.load(this.getClass().getClassLoader().getResourceAsStream("DBConfig.properties"));
                        driver = prop.getProperty("driver");
                        url = prop.getProperty("url");
                        user = prop.getProperty("user");
                        password = prop.getProperty("password");
                        Class.forName(driver);
                        Connection conn = DriverManager.getConnection(
                                        url, user, password);
                        return conn;
                } catch (Exception e) {
                        e.printStackTrace();
                }
                return null;
        }
        public Connection getConnection(String driver, String url, String user,
                        String password) {
                // Class.forName()
                try {
                        Class.forName(driver);
                        // DriverManager get connection
                        Connection conn = DriverManager.getConnection(url, user, password);
                        return conn;
                } catch (Exception e) {
                        e.printStackTrace();
                }
                return null;
        }

        public Connection getConnection() {
                // Class.forName()
                try {
                        Class.forName("com.mysql.jdbc.Driver");
                        // DriverManager get connection
                        Connection conn = DriverManager.getConnection(
                                        "jdbc:mysql://localhost:3306/jsp_db", "root", "963963");
                        return conn;
                } catch (Exception e) {
                        e.printStackTrace();
                }
                return null;
        }

}

SQLConstants.java

Link.java

DBConfig.properties

link.jsp

<%@ page language="java" import="java.util.*" pageEncoding="gbk"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="redking"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
    <head>
        <base href="<%=basePath%>">
        <title>My JSP 'link.jsp' starting page</title>
        <meta http-equiv="pragma" content="no-cache">
        <meta http-equiv="cache-control" content="no-cache">
        <meta http-equiv="expires" content="0">
        <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
        <meta http-equiv="description" content="This is my page">
        

    </head>
    <body>
        <form name="f1" id="f1" action="<%=path %>/servlet/LinkServlet?methodName=add" method="post">
            <table border="0">
                <tr>
                    <td>Name:</td>
                    <td><input type="text" name="name" ></td>
                </tr>
                <tr>
                    <td>Url:</td>
                    <td><input type="text" name="url"></td>
                </tr>
                <tr>
                    <td colspan="2" align="center"><input type="submit" value="Add"></td>
                </tr>
            </table>
        </form>
        <hr/>
        <form name="f2" action="<%=path %>/servlet/LinkServlet?methodName=delete" method="post">
        <table>
                <tr><th>ID</th><th>Name</th><th>URL</th><th>Edit</th><th>Delete</th></tr>
                <redking:forEach var="1" items="${LinkList}">
                        <tr>
                                <td>${l.id }</td>
                                <td>${l.name }</td>
                                <td>${l.url }</td>
                                <td><a href="<%=path %>/servlet/LinkServlet?methodName=forward&id=${l.id }">Edit</a></td>
                                <td><input type="checkbox" name="ids" value="${l.id }"/></td>
                        </tr>
                </redking:forEach>
                <tr>
                        <td>
                                <input type="submit" value="Delete"/>
                        </td>
                </tr>
        </table>
        </form>
    </body>
</html>

editLink.jsp

----------------------------------End----------------------------------

JDBC+Servlet+JSP整合開發之31-JSP項目實戰

再談23種設計模式（3）：行爲型模式（學習筆記）

Power Automate Desktop 安裝完，登錄後老是提示one driver 錯誤

微前端學習筆記(4):從微前端到微模塊之EMP與hel-micro方案探索

微前端學習筆記（1）：微前端總體架構概述，從微服務發微

985 碩士程序員，空窗 4 個月沒有 Offer！

一文搞懂 Spring 循環依賴

賽博鬥地主——使用大語言模型扮演Agent智能體玩牌類遊戲。

VScode右鍵打開(添加到右鍵)

記一次 .NET某工控視覺自動化系統卡死分析

WindowsServer--SQL Server搭建主從同步實現讀寫分離 - 事務性分發

JDBC+Servlet+JSP整合開發之26.JSP內建對象

JDBC+Servlet+JSP整合開發之27.JSP自定義標籤

CentOS6.4之文本編輯器Vi/Vim

JDBC+Servlet+JSP整合開發之28-JSP_標準標籤（JSTL）

CentOS6.4 Linux常用命令

Mac下配置sublime實現LaTeX

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

linux以太網驅動總結