Javaweb 增删改查

Javaweb Maven构建最简单的增删改查

一、项目结构

二、运行截图

三、maven所需依赖

<dependencies>
      <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
      </dependency>
    
      <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
      </dependency>
    
      <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
      <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>5.1.49</version>
      </dependency>
          
      <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
      </dependency>
          
      <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>javax.servlet.jsp-api</artifactId>
        <version>2.3.1</version>
      </dependency>
          
      <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
      </dependency>
    </dependencies>

四、数据表sql文件(Navicat导入就行)

/*
 Navicat Premium Data Transfer

 Source Server         : tttt
 Source Server Type    : MySQL
 Source Server Version : 50528
 Source Host           : localhost:3306
 Source Schema         : mydb

 Target Server Type    : MySQL
 Target Server Version : 50528
 File Encoding         : 65001

 Date: 20/07/2020 15:37:03
*/

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for stu
-- ----------------------------
DROP TABLE IF EXISTS `stu`;
CREATE TABLE `stu`  (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `sex` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `age` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  `phone_numb` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Table structure for users
-- ----------------------------
DROP TABLE IF EXISTS `users`;
CREATE TABLE `users`  (
  `uname` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户名',
  `upwd` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '密码',
  PRIMARY KEY (`uname`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

SET FOREIGN_KEY_CHECKS = 1;

五、项目构建

1、Dao 目录下

​ 构建数据连接（BaseDao.java）

​ 写UserDao.java、StuDao.java

public class BaseDao {

    //数据库参数
    private static final String driver = "com.mysql.jdbc.Driver";
    private static final String url = "jdbc:mysql://localhost:3306/mydb";
    //用户名、密码要是自己的
    private static final String user = "root";
    private static final String password = "root";

    //加载驱动
    static {
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    //1.获取连接
    public Connection getConn() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }
    //2.释放资源
    public void close(Connection conn, Statement st, ResultSet rs){
        try {
            if(conn != null)
                conn.close();
            if (st != null)
                st.close();
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    //关闭连接
    public void close(Connection conn, Statement st){
        try {
            if(conn != null)
                conn.close();
            if (st != null)
                st.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

---

public class StuDao {
    BaseDao baseDao = new BaseDao();

    public List<Stu> queryStus(String sex)  {
        if (sex == null){
            sex = "";
        }
        Connection conn = null;
        //1.预编译
        PreparedStatement pst = null;
        //2.结果集
        ResultSet rs = null;
        List<Stu> stuList = new ArrayList<>();
        try {
            conn = baseDao.getConn();
            //3.sql
            String sql = "select * from Stu where sex like ?";
            //4.预编译sql
            pst = conn.prepareStatement(sql);
            pst.setString(1, "%"+sex+"%");
            rs = pst.executeQuery();
            //6.遍历结果集
            while (rs.next()){
                int id = rs.getInt("id");
                String name = rs.getString("name");//用户名
                String sex1 = rs.getString("sex");//密码
                String age = rs.getString("age");//密码
                String phone_numb = rs.getString("phone_numb");//密码
                stuList.add(new Stu(id,name, sex1, age,phone_numb));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //最后记得关闭资源
            baseDao.close(conn, pst, rs);
        }
        return stuList;
    }

//    public static void main(String[] args) {
//        StuDao stuDao = new StuDao();
//        System.out.println("stuDao.queryStus() = " + stuDao.queryStus());
//    }

    public Boolean deleteStu(int id) {
        //1.获取连接
        Connection conn = null;
        //2.预编译
        PreparedStatement pst = null;
        //3.sql
        String sql = "delete from stu where id = ?";
        try {
            conn = baseDao.getConn();
            //预编译sql
            pst = conn.prepareStatement(sql);
            //注入参数
            pst.setInt(1,id);
            //执行sql
            return pst.executeUpdate() > 0;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            baseDao.close(conn, pst);
        }
        return false;
    }
}

---

package com.zking.dao;

import com.zking.entity.User;

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

/**
 * @author Tanglei
 * @date 2020/7/19 - 16:17
 */
public class UserDao {

    BaseDao baseDao = new BaseDao();

    public User checkUser(User user)  {
        User user1 = null;
        Connection conn = null;
        //1.预编译
        PreparedStatement pst = null;
        //2.结果集
        ResultSet rs = null;
        try {
            conn = baseDao.getConn();
            //3.sql
            String sql = "select * from users where uname = ? and upwd = ?";
            //4.预编译sql
            pst = conn.prepareStatement(sql);
            //5.注入参数
            Object[] params = {user.getUname(), user.getUpwd()};
            for (int i = 0; i < params.length; i++) {
                pst.setObject(i+1, params[i]);
            }
            rs = pst.executeQuery();
            //6.遍历结果集
            while (rs.next()){
                String uname = rs.getString("uname");//用户名
                String upwd = rs.getString("upwd");//密码
                user1 = new User(uname, upwd);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //最后记得关闭资源
            baseDao.close(conn, pst, rs);
        }
        return user1;
    }
    public List<User> queryUsers()  {
        Connection conn = null;
        //1.预编译
        PreparedStatement pst = null;
        //2.结果集
        ResultSet rs = null;
        List<User> userList = new ArrayList<>();
        try {
            conn = baseDao.getConn();
            //3.sql
            String sql = "select * from users";
            //4.预编译sql
            pst = conn.prepareStatement(sql);
            rs = pst.executeQuery();
            //6.遍历结果集
            while (rs.next()){
                String uname = rs.getString("uname");//用户名
                String upwd = rs.getString("upwd");//密码
                userList.add(new User(uname, upwd));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }finally {
            //最后记得关闭资源
            baseDao.close(conn, pst, rs);
        }
        return userList;
    }
}

2、实体类

​ User.java，Stu.java ( ！getter set 和构造方法自己快捷键生成 ！ )

public class Stu {
    private int id;//id
    private String name;//姓名
    private String sex;//性别
    private String age;//年龄
    private String phone_numb;//手机号
}

public class User {
    private String uname;//用户名
    private String upwd;//用户密码
}

3、jsp页面

​ login.jsp、showStu.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<form action="login?method=login" method="post">
    <table cellpadding="0" border="1" align="center">
        <tbody>
        <tr>
            <td colspan="2" align="center">登 陆</td>
        </tr>
        <tr>
            <td>
                <label>用户名：</label>
            </td>
            <td>
                <input type="text" name="username">
            </td>
        </tr>
        <tr>
            <td>
                <label>密 码：</label>
            </td>
            <td>
                <input type="text" name="password">
            </td>
        </tr>
        <tr>
            <td colspan="2" align="center">
                <button type="submit">登 陆</button>
                <button id="reSet">重置</button>
            </td>
        </tr>
        </tbody>
    </table>
</form>
</body>
<script>
    document.getElementById("#reSet").click(function () {
        document.getElementByName("username").val = "";
        document.getElementByName("password").val = "";
    });
</script>
</html>

---

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>显示所有学生数据</title>
</head>
<script>
    function buttonClick() {
        var sex = document.getElementById("sex").value;
        window.location.href = "stu?method=queryStusBySex&sex="+sex;
    }
</script>
<body>
    <thead>
        <label>性别:</label>
        <input type="text" value="" id="sex" name="sex">
        <input  id="button" type="button" value="查询" οnclick="buttonClick();">
        <table align="center" border="1" cellpadding="10">
        <tr>
            <td colspan="6" align="center">学 生 列 表</td>
        </tr>
        <tr>
            <td>编号</td>
            <td>姓名</td>
            <td>性别</td>
            <td>年龄</td>
            <td>电话</td>
            <td>操作</td>
        </tr>
    </thead>
    <tbody>
        <c:forEach items="${stuList}" var="stu">
            <tr>
                <td>${stu.id}</td>
                <td>${stu.name}</td>
                <td>${stu.sex}</td>
                <td>${stu.age}</td>
                <td>${stu.phone_numb}</td>
                <td>
                    <a href="stu?method=deleteStu&id=${stu.id}">删除</a>
                </td>
            </tr>
        </c:forEach>
    </tbody>
</table>
</body>
</html>

4、最后的Servlet

​ LoginServlet、StuServlet

@WebServlet(urlPatterns = {"/login"})
public class LoginServlet extends HttpServlet {
    UserDao userDao = new UserDao();
    StuDao stuDao = new StuDao();

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String method = request.getParameter("method");
        System.out.println("method = " + method);

        if("login".equals(method)){
            login(request,response);
        }
    }
	//登陆方法
    private void login(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String userName = request.getParameter("username");//获取表单提交的用户名
        String passWord = request.getParameter("password");//密码
        User loginUser = new User(userName, passWord);
        User checkUser = userDao.checkUser(loginUser);//验证
        if (checkUser != null){//验证通过
            List<Stu> stuList = stuDao.queryStus("");
            System.out.println("stuList = " + stuList);
            request.setAttribute("stuList", stuList);
            request.getRequestDispatcher("/WEB-INF/views/showStus.jsp").forward(request, response);
        }else {
            response.sendRedirect("login.jsp");
        }
    }
}

---

@WebServlet(urlPatterns = {"/stu"})
public class StuServlet extends HttpServlet {
    StuDao stuDao = new StuDao();

    @Override
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String method = request.getParameter("method");
        System.out.println("method = " + method);
        if ("showStus".equals(method)){
            showStus(request,response);
        }else if("deleteStu".equals(method)){
            deleteStu(request,response);
        }else if("queryStusBySex".equals(method)){
            queryStusBySex(request,response);
        }
    }

    //通过性别查询所有学生信息
    private void queryStusBySex(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String sex = request.getParameter("sex");
        List<Stu> stuList = stuDao.queryStus(sex);
        request.setAttribute("stuList", stuList);
        request.getRequestDispatcher("/WEB-INF/views/showStus.jsp").forward(request, response);
    }
	//删除
    private void deleteStu(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int id = Integer.parseInt(request.getParameter("id"));
        Boolean flag = stuDao.deleteStu(id);
        if (flag){
            response.sendRedirect("stu?method=showStus");
        }
    }
	//查询所有学生
    private void showStus(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<Stu> stuList = stuDao.queryStus("");
        request.setAttribute("stuList", stuList);
        request.getRequestDispatcher("/WEB-INF/views/showStus.jsp").forward(request, response);
    }
}
       if (flag){
            response.sendRedirect("stu?method=showStus");
        }
    }
	//查询所有学生
    private void showStus(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        List<Stu> stuList = stuDao.queryStus("");
        request.setAttribute("stuList", stuList);
        request.getRequestDispatcher("/WEB-INF/views/showStus.jsp").forward(request, response);
    }
}

六、写在最后

这是我自己学习中的实际项目代码，适合有一定Java基础的学习者，复习一下JavaEE的 jsp、servlet，首次发帖，勿喷，有什么问题可以评论

要源码请联系我 q:1427554362