學習筆記專區

package model;

public class DemoDAO {

    public DemoDAO() {

       System.out.println("DemoDAO's constructor");

    }

}

package model;

public class DemoService {

    // 範例二

    private DemoDAO dao = null;

    public DemoService(DemoDAO dao) {

       // 我是建構子

       this.dao = dao;

    }

}

<?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="logProvider" class="util.LogProvider"></bean>

    <!-- ↑這就是一個Bean物件，被呼叫時就會new出一個util.LogProvider的物件 -->

    <!-- 範例二： -->

    <bean id="demoDAO" class="model.DemoDAO"></bean>

    <!-- ↑這一行對應到TestDemoService中的DemoDAO dao = new DemoDAO();也就是new一個DemoDAO物件 -->

    <bean id="demoService" class="model.DemoService">

    <constructor-arg ref="demoDAO"></constructor-arg>

    </bean>

<!--   ↑這三行對應到TestDemoService中的DemoService service = new DemoService(dao);  -->

<!--   其中建構子內dao由<constructor-arg ref="demoDAO"></constructor-arg>這一行指定 -->

</beans>

package org.iiiedu.samuel.ProjSpringDemo;

import model.DemoDAO;

import model.DemoService;

public class TestDemoService {

    public static void main(String[] args) {

//     範例二

       DemoDAO dao = new DemoDAO();

       DemoService service = new DemoService(dao);

    }

}