利用Spring框架为自己的校园卡充值(推荐)

package com.cqust.dao;

import com.cqust.entity.StudentCard;

public class CardDao {
    public void save(double money){
        System.out.println("您的充值金额为：¥" + money);
    }
}

package com.cqust.entity;

public class StudentCard {
    double balance;         //定义余额

    public double getBalance() {
        return balance;     //返回余额
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }
}

package com.cqust.biz;

import com.cqust.dao.CardDao;
import com.cqust.entity.StudentCard;

public class CardBiz {
    private StudentCard studentCard;	//定义一个StudentCard对象
    private CardDao cardDao;			//定义一个CardDao对象
    public void setStudentCard(StudentCard studentCard) {
        this.studentCard = studentCard;
    }
    public void setCardDao(CardDao cardDao) {
        this.cardDao = cardDao;
    }
    public void charge(double money){
        cardDao.save(money);        					//调用cardDao里的save方法
        double sum = studentCard.getBalance() + money;	//将学生卡里的余额加上需要充值的金额
        System.out.println("充值成功！当前您的余额为：¥" + sum);	//输出充值后的金额
    }
}

import com.cqust.biz.CardBiz;
import com.cqust.entity.StudentCard;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class test {
    public static void main(String[] args) {
        //获取核心容器(IoC)对象
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        //获取xml文件中的bean
        CardBiz cardBiz= (CardBiz) applicationContext.getBean("cardBiz");
        //获取xml文件中的bean
        StudentCard studentCard= (StudentCard) applicationContext.getBean("studentCard");
        //传一个数值给cardBiz里的charge方法进行充值，此处我给的800，吃好一点哈哈哈
        cardBiz.charge(800);
    }
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="studentCard" class="com.cqust.entity.StudentCard">
        <property name="balance" value="88.88"></property>      <!--将学生卡的余额设置为88.8元-->
    </bean>
    <bean id="cardDao" class="com.cqust.dao.CardDao"></bean>
    <bean id="cardBiz" class="com.cqust.biz.CardBiz">
        <property name="studentCard"  ref="studentCard"></property>
        <property name="cardDao" ref="cardDao"></property>
    </bean>
</beans>