创立数据库表 examstudent，要求使用MVC模式实现下面的需求。

创立数据库表 examstudent，要求使用MVC模式实现下面的需求。
表结构如下：
DROP TABLE IF EXISTS examstudent;
CREATE TABLE examstudent (
FlowID int(11) NOT NULL AUTO_INCREMENT,
Type int(11) DEFAULT NULL,
IDCard varchar(18) DEFAULT NULL,
ExamCard varchar(15) DEFAULT NULL,
StudentName varchar(20) DEFAULT NULL,
Location varchar(20) DEFAULT NULL,
Grade int(11) DEFAULT NULL,
PRIMARY KEY (FlowID)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

INSERT INTO examstudent VALUES ('4', '854524195263214584', '200523164754005', '王小红', '太原', '60');

1)在html页面以表格的方式显示所有的学生信息。页面上存在“添加学生”的链接

2)通过html页面插入一个新的student 信息
提示：信息录入成功!

3)在html页面中，输入身份证号或准考证号可以查询到学生的基本信息。

4)在html页面中，完成学生信息的删除功能，根据IDCard的删除

import java.sql.*;
import java.util.ArrayList;

public class ExamStudent {
    private int flowId;
    private int type;
    private String iDCard;
    private String examCard;
    private String studentName;
    private String location;
    private int grade;

    public ExamStudent() {
    }

    public ExamStudent(int flowId, int type, String iDCard, String examCard,
                       String studentName, String location, int grade) {
        this.flowId = flowId;
        this.type = type;
        this.iDCard = iDCard;
        this.examCard = examCard;
        this.studentName = studentName;
        this.location = location;
        this.grade = grade;
    }

    public ExamStudent(String iDCard, String examCard, String studentName,
                       String location, int grade) {
        this.type = 0;
        this.iDCard = iDCard;
        this.examCard = examCard;
        this.studentName = studentName;
        this.location = location;
        this.grade = grade;
    }

    public int getFlowId() {
        return flowId;
    }

    public void setFlowId(int flowId) {
        this.flowId = flowId;
    }

    public int getType() {
        return type;
    }

    public void setType(int type) {
        this.type = type;
    }

    public String getIDCard() {
        return iDCard;
    }

    public void setIDCard(String iDCard) {
        this.iDCard = iDCard;
    }

    public String getExamCard() {
        return examCard;
    }

    public void setExamCard(String examCard) {
        this.examCard = examCard;
    }

    public String getStudentName() {
        return studentName;
    }

    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public String getLocation() {
        return location;
    }

    public void setLocation(String location) {
        this.location = location;
    }

    public int getGrade() {
        return grade;
    }

    public void setGrade(int grade) {
        this.grade = grade;
    }

    // 从ResultSet中提取学生信息并返回一个ExamStudent对象
    private static ExamStudent extractData(ResultSet rs) throws SQLException {
        ExamStudent student = new ExamStudent();
        student.setFlowId(rs.getInt("FlowID"));
        student.setType(rs.getInt("Type"));
        student.setIDCard(rs.getString("IDCard"));
        student.setExamCard(rs.getString("ExamCard"));
        student.setStudentName(rs.getString("StudentName"));
        student.setLocation(rs.getString("Location"));
        student.setGrade(rs.getInt("Grade"));
        return student;
    }

    // 获取所有学生的信息
    public static ArrayList<ExamStudent> getAllStudents() throws SQLException {
        ArrayList<ExamStudent> students = new ArrayList<ExamStudent>();
        Connection conn = DBUtil.getConnection();
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select * from examstudent");
        while (rs.next()) {
            ExamStudent student = extractData(rs);
            students.add(student);
        }
        rs.close();
        stmt.close();
        conn.close();
        return students;
    }

    // 根据身份证号或准考证号查找学生的信息
    public static ExamStudent findStudent(String id) throws SQLException {
        ExamStudent student = null;
        Connection conn = DBUtil.getConnection();
        Statement stmt = conn.createStatement();
        ResultSet rs = stmt.executeQuery("select * from examstudent where " +
                "IDCard = '" + id + "' or ExamCard = '" + id + "'");
        if (rs.next()) {
            student = extractData(rs);
        }
        rs.close();
        stmt.close();
        conn.close();
        return student;
    }

    // 插入一个新的学生信息到数据库中
    public boolean insert() throws SQLException {
        if (type != 0) {
            return false;
        }
        Connection conn = DBUtil.getConnection();
        Statement stmt = conn.createStatement();
        String sql = "insert into examstudent(Type, IDCard, ExamCard, StudentName, " +
                "Location, Grade) values (0, '" + iDCard + "', '" + examCard +
                "', '" + studentName + "', '" + location + "', " + grade + ")";
        int row = stmt.executeUpdate(sql);
        stmt.close();
        conn.close();
        return row == 1;
    }

    // 根据身份证号码删除学生信息
    public static boolean delete(String id) throws SQLException {
        Connection conn = DBUtil.getConnection();
        Statement stmt = conn.createStatement();
        String sql = "delete from examstudent where IDCard = '" + id + "'";
        int row = stmt.executeUpdate(sql);
        stmt.close();
        conn.close();
        return row == 1;
    }
}


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Exam Students</title>
    <style>
        th, td {
            padding: 5px;
            text-align: center;
        }

        table {
            border-collapse: collapse;
            margin: 20px auto;
        }

        input[name="id"] {
            margin-left: 20px;
        }

        input[type="submit"] {
            margin-left: 20px;
        }
    </style>
</head>
<body>
<h1>Exam Students</h1>
<table border="1">
    <tr>
        <th>FlowID</th>
        <th>Type</th>
        <th>IDCard</th>
        <th>ExamCard</th>
        <th>StudentName</th>
        <th>Location</th>
        <th>Grade</th>
    </tr>
    <% ArrayList<ExamStudent> students = ExamStudent.getAllStudents(); %>
    <% for (ExamStudent student : students) { %>
        <tr>
            <td><%= student.getFlowId() %></td>
            <td><%= student.getType() %></td>
            <td><%= student.getIDCard() %></td>
            <td><%= student.getExamCard() %></td>
            <td><%= student.getStudentName() %></td>
            <td><%= student.getLocation() %></td>
            <td><%= student.getGrade() %></td>
        </tr>
    <% } %>
</table>
<form action="addStudent.jsp">
    <input type="submit" value="Add Student">
</form>
<form action="findStudent.jsp" method="post">
    <label for="id">IDCard/ExamCard:</label>
    <input type="text" name="id">
    <input type="submit" value="Find">
</form>
<form action="deleteStudent.jsp" method="post">
    <label for="id">IDCard:</label>
    <input type="text" name="id">
    <input type="submit" value="Delete">
</form>
</body>
</html>


addStudent.jsp：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Add Student</title>
</head>
<body>
<h1>Add Student</h1>
<%
    if (request.getMethod().equalsIgnoreCase("post")) {
        String idCard = request.getParameter("idCard");
        String examCard = request.getParameter("examCard");
        String studentName = request.getParameter("studentName");
        String location = request.getParameter("location");
        int grade = Integer.parseInt(request.getParameter("grade"));
        ExamStudent student = new ExamStudent(idCard, examCard, studentName, location, grade);
        boolean added = student.insert();
        if (added) {
            out.println("Information added successfully!");
        } else {
            out.println("Failed to add information!");
        }
    }
%>
<form action="addStudent.jsp" method="post">
    <label for="idCard">IDCard:</label>
    <input type="text" name="idCard"><br>
    <label for="examCard">ExamCard:</label>
    <input type="text" name="examCard"><br>
    <label for="studentName">StudentName:</label>
    <input type="text" name="studentName"><br>
    <label for="location">Location:</label>
    <input type="text" name="location"><br>
    <label for="grade">Grade:</label>
    <input type="text" name="grade"><br>
    <input type="submit" value="Save">
</form>
<form action="index.jsp">
    <input type="submit" value="Back">
</form>
</body>
</html>
findStudent.jsp：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Find Student</title>
</head>
<body>
<h1>Find Student</h1>
<%
    if (request.getMethod().equalsIgnoreCase("post")) {
        String id = request.getParameter("id");
        ExamStudent student = ExamStudent.findStudent(id);
        if (student != null) {
            out.println("IDCard: " + student.getIDCard() + "<br>");
            out.println("ExamCard: " + student.getExamCard() + "<br>");
            out.println("StudentName: " + student.getStudentName() + "<br>");
            out.println("Location: " + student.getLocation() + "<br>");
            out.println("Grade: " + student.getGrade() + "<br>");
        } else {
            out.println("No such student!");
        }
    }
%>
<form action="findStudent.jsp" method="post">
    <label for="id">IDCard/ExamCard:</label>
    <input type="text" name="id">
    <input type="submit" value="Find">
</form>
<form action="index.jsp">
    <input type="submit" value="Back">
</form>
</body>
</html>
deleteStudent.jsp：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Delete Student</title>
</head>
<body>
<h1>Delete Student</h1>
<%
    if (request.getMethod().equalsIgnoreCase("post")) {
        String id = request.getParameter("id");
        boolean deleted = ExamStudent.delete(id);
        if (deleted) {
            out.println("Information deleted successfully!");
        } else {
            out.println("Failed to delete information!");
        }
    }
%>
<form action="deleteStudent.jsp" method="post">
    <label for="id">IDCard:</label>
    <input type="text" name="id"><br>
    <input type="submit" value="Delete">
</form>
<form action="index.jsp">
    <input type="submit" value="Back">
</form>
</body>
</html>


import java.sql.*;

public class DBUtil {
    private static final String URL = "jdbc:mysql://localhost:3306/testDB?useUnicode=true&characterEncoding=utf8";
    private static final String USER = "root";
    private static final String PASSWORD = "root";

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    public static void close(Connection conn, Statement stmt, ResultSet rs) throws SQLException {
        if (rs != null) {
            rs.close();
        }
        if (stmt != null) {
            stmt.close();
        }
        if (conn != null) {
            conn.close();
        }
    }
}