代码的魔法师：Java反射工厂模式详解

package world.xuewei;
/**
 * 用户实体
 *
 * @author 薛伟
 * @since 2023/9/14 17:17
 */
public class User {
    /**
     * 用户名
     */
    private String userName;
    /**
     * 密码
     */
    private String password;
    public User() {
    }
    public User(String userName, String password) {
        this.userName = userName;
        this.password = password;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{" +
                "userName='" + userName + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

package world.xuewei;
/**
 * 用户服务接口
 *
 * @author 薛伟
 * @since 2023/9/14 17:17
 */
public interface UserService {
    /**
     * 用户登录
     *
     * @param userName 用户名
     * @param password 密码
     * @return 登录用户
     */
    User login(String userName, String password);
}

package world.xuewei;
/**
 * 用户服务接口实现类
 *
 * @author 薛伟
 * @since 2023/9/14 17:19
 */
public class UserServiceImpl implements UserService {
    @Override
    public User login(String userName, String password) {
        System.out.println("当前登录用户为：" + userName);
        return new User(userName, password);
    }
}

package world.xuewei;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
/**
 * 工厂类
 *
 * @author 薛伟
 * @since 2023/9/14 17:23
 */
public class BeanFactory {
    /**
     * 存储配置文件内容
     */
    private static final Properties properties = new Properties();
    static {
        // 加载配置文件内容
        try (InputStream inputStream = BeanFactory.class.getResourceAsStream("/bean.properties")) {
            properties.load(inputStream);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
    /**
     * 获取 Bean 对象
     *
     * @return 服务实现类
     */
    public static Object getBean(String beanName) {
        Object bean = null;
        try {
            // 通过全限定类名反射创建对象
            Class<?> userServiceClass = Class.forName(String.valueOf(properties.get(beanName)));
            bean = userServiceClass.newInstance();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bean;
    }
}

package world.xuewei;
/**
 * 主方法
 *
 * @author 薛伟
 * @since 2023/9/14 17:21
 */
public class MainApp {
    public static void main(String[] args) {
        UserService userService = (UserService) BeanFactory.getBean("userService");
        userService.login("张三", "123456");
    }
}

# bean.properties
userService=world.xuewei.UserServiceImpl