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;

很好，这是一个比较完整的jdbc项目，需要分步骤来实现。

1. 创建jdbc项目并连接数据库

首先需要创建一个Java项目，并添加JDBC驱动jar包，然后在代码中连接数据库。

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DatabaseConnection {
    private static final String URL = "jdbc:mysql://localhost:3306/demo";
    private static final String USER = "root";
    private static final String PASSWORD = "root";

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

2. 实现部门的添加和修改功能

定义一个`DepartmentDao`接口，里面包含添加和修改部门的方法。

public interface DepartmentDao {
    void addDepartment(Department department) throws SQLException;

    void updateDepartment(int id, String newName) throws SQLException;
}

然后实现接口中的方法。

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class DepartmentDaoImpl implements DepartmentDao {
    private Connection connection;

    public DepartmentDaoImpl(Connection connection) {
        this.connection = connection;
    }

    @Override
    public void addDepartment(Department department) throws SQLException {
        String sql = "INSERT INTO department (name) VALUES (?)";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1, department.getName());
        statement.executeUpdate();
        statement.close();
    }

    @Override
    public void updateDepartment(int id, String newName) throws SQLException {
        String sql = "UPDATE department SET name=? WHERE id=?";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1, newName);
        statement.setInt(2, id);
        statement.executeUpdate();
        statement.close();
    }
}

3. 实现员工的添加和查询功能

定义一个`EmployeeDao`接口，里面包含添加和查询员工的方法。

import java.sql.SQLException;
import java.util.List;

public interface EmployeeDao {
    void addEmployee(Employee employee) throws SQLException;

    List<Employee> getAllEmployees() throws SQLException;

    List<Employee> getEmployeesByName(String name) throws SQLException;
}

然后实现接口中的方法。

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 EmployeeDaoImpl implements EmployeeDao {
    private Connection connection;

    public EmployeeDaoImpl(Connection connection) {
        this.connection = connection;
    }

    @Override
    public void addEmployee(Employee employee) throws SQLException {
        String sql = "INSERT INTO employee (name, age, gender, department_id) VALUES (?, ?, ?, ?)";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1, employee.getName());
        statement.setInt(2, employee.getAge());
        statement.setString(3, employee.getGender());
        statement.setInt(4, employee.getDepartmentId());
        statement.executeUpdate();
        statement.close();
    }

    @Override
    public List<Employee> getAllEmployees() throws SQLException {
        String sql = "SELECT * FROM employee";
        PreparedStatement statement = connection.prepareStatement(sql);
        ResultSet resultSet = statement.executeQuery();
        List<Employee> employees = new ArrayList<>();
        while (resultSet.next()) {
            Employee employee = new Employee();
            employee.setId(resultSet.getInt("id"));
            employee.setName(resultSet.getString("name"));
            employee.setAge(resultSet.getInt("age"));
            employee.setGender(resultSet.getString("gender"));
            employee.setDepartmentId(resultSet.getInt("department_id"));
            employees.add(employee);
        }
        resultSet.close();
        statement.close();
        return employees;
    }

    @Override
    public List<Employee> getEmployeesByName(String name) throws SQLException {
        String sql = "SELECT * FROM employee WHERE name=?";
        PreparedStatement statement = connection.prepareStatement(sql);
        statement.setString(1, name);
        ResultSet resultSet = statement.executeQuery();
        List<Employee> employees = new ArrayList<>();
        while (resultSet.next()) {
            Employee employee = new Employee();
            employee.setId(resultSet.getInt("id"));
            employee.setName(resultSet.getString("name"));
            employee.setAge(resultSet.getInt("age"));
            employee.setGender(resultSet.getString("gender"));
            employee.setDepartmentId(resultSet.getInt("department_id"));
            employees.add(employee);
        }
        resultSet.close();
        statement.close();
        return employees;
    }
}

4. 整合以上功能并实现三层结构

现在可以将以上功能整合起来，创建一个`Service`层，提供给外部调用。

import java.sql.Connection;
import java.sql.SQLException;
import java.util.List;

public class EmployeeService {
    private DepartmentDao departmentDao;
    private EmployeeDao employeeDao;

    public EmployeeService() {
        try {
            Connection connection = DatabaseConnection.getConnection();
            departmentDao = new DepartmentDaoImpl(connection);
            employeeDao = new EmployeeDaoImpl(connection);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void addDepartment(Department department) {
        try {
            departmentDao.addDepartment(department);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void updateDepartment(int id, String newName) {
        try {
            departmentDao.updateDepartment(id, newName);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public void addEmployee(Employee employee) {
        try {
            employeeDao.addEmployee(employee);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public List<Employee> getAllEmployees() {
        try {
            return employeeDao.getAllEmployees();
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }

    public List<Employee> getEmployeesByName(String name) {
        try {
            return employeeDao.getEmployeesByName(name);
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }
}

这里的`Service`层对外提供了四个方法，分别是添加部门、修改部门、添加员工、查询所有员工和根据姓名查询员工。

至此，整个jdbc项目就完成了。