2、创建jdbc项目，实现数据库连接,并完成如下功能: 1)输入一个部门]的信息，完成部门的添加; 2)根据部门编号针对部门门名称进行修改的功能:输入部门编号和修改 名称的修改! 3)输入一个员工的信息，完成员工的添加。 4)完成如下查询: 4.1)查询所有员工信息; 4.2)输入姓名，查询员工信息; 3、创建jdbc项目，使用逻辑三层结构,把第2题的功能重新实现一遍;

对于第一部分，需要先创建一个数据库，在其中创建两个表，分别为dept和employee。dept表包含dept_id和dept_name两个字段，employee表包含emp_id，emp_name，dept_id三个字段。然后在Java中使用JDBC连接数据库，实现对部门和员工的添加、修改和查询操作。

以下是一个简单的示例代码，仅供参考：

import java.sql.*;

public class JdbcDemo {
    private static final String URL = "jdbc:mysql://localhost:3306/db_name";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";

    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            // 添加部门
            String sql = "insert into dept(dept_id, dept_name) values (?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, 1);
            ps.setString(2, "Sales");
            ps.executeUpdate();

            // 修改部门名称
            sql = "update dept set dept_name = ? where dept_id = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, "Marketing");
            ps.setInt(2, 1);
            ps.executeUpdate();

            // 添加员工
            sql = "insert into employee(emp_id, emp_name, dept_id) values (?, ?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, 1);
            ps.setString(2, "John");
            ps.setInt(3, 1);
            ps.executeUpdate();

            // 查询所有员工信息
            sql = "select emp_id, emp_name, dept_name from employee inner join dept on employee.dept_id = dept.dept_id";
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
            while (rs.next()) {
                System.out.println(rs.getInt(1) + " " + rs.getString(2) + " " + rs.getString(3));
            }

            // 根据姓名查询员工信息
            sql = "select emp_id, emp_name, dept_name from employee inner join dept on employee.dept_id = dept.dept_id where emp_name = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, "John");
            rs = ps.executeQuery();
            while (rs.next()) {
                System.out.println(rs.getInt(1) + " " + rs.getString(2) + " " + rs.getString(3));
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (rs != null) rs.close();
                if (ps != null) ps.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

对于第二部分，需要在第一部分的基础上进行重构，实现逻辑三层结构。这里简单介绍一下逻辑三层结构的组成：

- 数据访问层（DAO）：负责数据库的读写操作，将数据保存到数据库或从数据库中读取数据并返回给上层。
- 业务逻辑层（Service）：负责对业务逻辑的处理，将数据传递给DAO层进行保存或读取，同时对数据进行加工和处理。
- 表现层（Presentation）：负责展示数据，将数据展示给用户或接收用户的输入，并调用Service层对数据进行处理。

以下是一个简单的示例代码，仅供参考：

1. 数据访问层（DAO）

import java.sql.*;

public class DeptDAO {
    private static final String URL = "jdbc:mysql://localhost:3306/db_name";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";

    public void addDept(int deptId, String deptName) {
        Connection conn = null;
        PreparedStatement ps = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            String sql = "insert into dept(dept_id, dept_name) values (?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, deptId);
            ps.setString(2, deptName);
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (ps != null) ps.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public void updateDept(int deptId, String deptName) {
        Connection conn = null;
        PreparedStatement ps = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            String sql = "update dept set dept_name = ? where dept_id = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, deptName);
            ps.setInt(2, deptId);
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (ps != null) ps.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public void addEmployee(int empId, String empName, int deptId) {
        Connection conn = null;
        PreparedStatement ps = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            String sql = "insert into employee(emp_id, emp_name, dept_id) values (?, ?, ?)";
            ps = conn.prepareStatement(sql);
            ps.setInt(1, empId);
            ps.setString(2, empName);
            ps.setInt(3, deptId);
            ps.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (ps != null) ps.close();
                if (conn != null) conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public ResultSet getAllEmployees() {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            String sql = "select emp_id, emp_name, dept_name from employee inner join dept on employee.dept_id = dept.dept_id";
            ps = conn.prepareStatement(sql);
            rs = ps.executeQuery();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return rs;
    }

    public ResultSet getEmployeeByName(String empName) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(URL, USERNAME, PASSWORD);

            String sql = "select emp_id, emp_name, dept_name from employee inner join dept on employee.dept_id = dept.dept_id where emp_name = ?";
            ps = conn.prepareStatement(sql);
            ps.setString(1, empName);
            rs = ps.executeQuery();
        } catch (Exception e) {
            e.printStackTrace();
        }

        return rs;
    }
}

2. 业务逻辑层（Service）

import java.sql.ResultSet;
import java.sql.SQLException;

public class DeptService {
    private DeptDAO deptDAO;

    public DeptService() {
        deptDAO = new DeptDAO();
    }

    public void addDept(int deptId, String deptName) {
        deptDAO.addDept(deptId, deptName);
    }

    public void updateDept(int deptId, String deptName) {
        deptDAO.updateDept(deptId, deptName);
    }

    public void addEmployee(int empId, String empName, int deptId) {
        deptDAO.addEmployee(empId, empName, deptId);
    }

    public void printAllEmployees() {
        ResultSet rs = deptDAO.getAllEmployees();
        try {
            while (rs.next()) {
                System.out.println(rs.getInt(1) + " " + rs.getString(2) + " " + rs.getString(3));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void printEmployeeByName(String empName) {
        ResultSet rs = deptDAO.getEmployeeByName(empName);
        try {
            while (rs.next()) {
                System.out.println(rs.getInt(1) + " " + rs.getString(2) + " " + rs.getString(3));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

3. 表现层（Presentation）

import java.util.Scanner;

public class Main {
    private static DeptService deptService;

    public static void main(String[] args) {
        deptService = new DeptService();

        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("1. 添加部门");
            System.out.println("2. 修改部门名称");
            System.out.println("3. 添加员工");
            System.out.println("4. 查询所有员工信息");
            System.out.println("5. 根据姓名查询员工信息");
            System.out.println("6. 退出");

            int choice = scanner.nextInt();
            if (choice == 1) {
                System.out.println("请输入部门编号和名称，以空格分隔：");
                int deptId = scanner.nextInt();
                String deptName = scanner.next();
                deptService.addDept(deptId, deptName);
            } else if (choice == 2) {
                System.out.println("请输入部门编号和新名称，以空格分隔：");
                int deptId = scanner.nextInt();
                String deptName = scanner.next();
                deptService.updateDept(deptId, deptName);
            } else if (choice == 3) {
                System.out.println("请输入员工编号、姓名和所在部门编号，以空格分隔：");
                int empId = scanner.nextInt();
                String empName = scanner.next();
                int deptId = scanner.nextInt();
                deptService.addEmployee(empId, empName, deptId);
            } else if (choice == 4) {
                deptService.printAllEmployees();
            } else if (choice == 5) {
                System.out.println("请输入员工姓名：");
                String empName = scanner.next();
                deptService.printEmployeeByName(empName);
            } else if (choice == 6) {
                break;
            } else {
                System.out.println("输入无效，请重新输入");
            }
        }
    }
}