Java简单增删改查项目

好的，我可以为您提供一个简单的 Java 增删改查项目示例。

首先，您需要创建一个 Java 项目，并创建一个名为 "Employee" 的类，表示雇员对象，代码如下：

public class Employee {
    private int id;
    private String name;
    private int age;
    private String position;
    
    public Employee(int id, String name, int age, String position) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.position = position;
    }
    
    // getter and setter methods
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getPosition() {
        return position;
    }
    public void setPosition(String position) {
        this.position = position;
    }
}

接下来，您需要创建一个数据库表来存储雇员信息。假设您创建了一个名为 "employee" 的表，包含以下列：

- id INT PRIMARY KEY
- name VARCHAR(50)
- age INT
- position VARCHAR(50)

然后，您需要创建一个名为 "EmployeeDAO" 的类，用于执行增删改查操作。代码如下：

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

public class EmployeeDAO {
    private Connection connection;
    
    public EmployeeDAO() {
        try {
            // 连接数据库
            connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/mydatabase", "root", "password");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    // 查询所有雇员
    public List<Employee> findAll() {
        List<Employee> employees = new ArrayList<>();
        try {
            Statement statement = connection.createStatement();
            ResultSet resultSet = statement.executeQuery("SELECT * FROM employee");
            while (resultSet.next()) {
                int id = resultSet.getInt("id");
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");
                String position = resultSet.getString("position");
                employees.add(new Employee(id, name, age, position));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return employees;
    }
    
    // 根据 ID 查询雇员
    public Employee findById(int id) {
        Employee employee = null;
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("SELECT * FROM employee WHERE id = ?");
            preparedStatement.setInt(1, id);
            ResultSet resultSet = preparedStatement.executeQuery();
            if (resultSet.next()) {
                String name = resultSet.getString("name");
                int age = resultSet.getInt("age");
                String position = resultSet.getString("position");
                employee = new Employee(id, name, age, position);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return employee;
    }
    
    // 添加雇员
    public void addEmployee(Employee employee) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("INSERT INTO employee(id, name, age, position) VALUES (?, ?, ?, ?)");
            preparedStatement.setInt(1, employee.getId());
            preparedStatement.setString(2, employee.getName());
            preparedStatement.setInt(3, employee.getAge());
            preparedStatement.setString(4, employee.getPosition());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    // 更新雇员信息
    public void updateEmployee(Employee employee) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("UPDATE employee SET name = ?, age = ?, position = ? WHERE id = ?");
            preparedStatement.setString(1, employee.getName());
            preparedStatement.setInt(2, employee.getAge());
            preparedStatement.setString(3, employee.getPosition());
            preparedStatement.setInt(4, employee.getId());
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    // 删除雇员
    public void deleteEmployee(int id) {
        try {
            PreparedStatement preparedStatement = connection.prepareStatement("DELETE FROM employee WHERE id = ?");
            preparedStatement.setInt(1, id);
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

最后，您可以在主方法中测试这些操作，例如：

public static void main(String[] args) {
    EmployeeDAO dao = new EmployeeDAO();
    
    // 查询所有雇员
    List<Employee> employees = dao.findAll();
    for (Employee employee : employees) {
        System.out.println(employee.getName());
    }
    
    // 根据 ID 查询雇员
    Employee employee = dao.findById(1);
    System.out.println(employee.getName());
    
    // 添加雇员
    Employee newEmployee = new Employee(4, "Tom", 25, "Developer");
    dao.addEmployee(newEmployee);
    
    // 更新雇员信息
    employee.setName("John");
    employee.setAge(30);
    dao.updateEmployee(employee);
    
    // 删除雇员
    dao.deleteEmployee(4);
}

希望这个示例能帮助您理解 Java 的增删改查操作。