Spring攻略学习笔记(3)调用构造程序创建Bean

     通常，当你为一个Bean指定了class属性，就将要求Spring IoC容器调用构造程序创建Bean。

     如下，有一个Product类，他有两个子类Battery和Disc。

    Product类： 

/*  
  * Copyright 2013-2015  
  */
package com.jackie.codeproject.springrecipesnote.springioc.shop;

/**
 * Title: Product.java
 *  产品抽象类
 * 
 * @author jackie
 * @since Apr 14, 2013 8:09:49 PM
 * @version V1.0
 */
public abstract class Product {
    private String name;
    private double price;
    
    public Product() {
        
    }

    /**
      * <p>Title: </p>
      * <p>含参构造函数</p>
      * @param name
      * @param price
      */    
    public Product(String name, double price) {
        this.name = name;
        this.price = price;
    }

    /**
     * @return the name
     */
    public String getName() {
        return name;
    }
    
    /**
     * @param name the name to set
     */
    public void setName(String name) {
        this.name = name;
    }
    
    /**
     * @return the price
     */
    public double getPrice() {
        return price;
    }
    
    /**
     * @param price the price to set
     */
    public void setPrice(double price) {
        this.price = price;
    }
    
    public String toString() {
        return name + " " + price;
    }
}

Battery类：

/*
 * Copyright 2013-2015
 */
package com.jackie.codeproject.springrecipesnote.springioc.shop;

/**
 * Title: Battery.java 类的功能说明
 * 
 * @author jackie
 * @since Apr 14, 2013 8:14:26 PM
 * @version V1.0
 */
public class Battery extends Product {

    private boolean rechargeable;

    public Battery() {
        super();
    }

    public Battery(String name, double price) {
        super(name, price);
    }

    /**
     * @return the rechargeable
     */
    public boolean isRechargeable() {
        return rechargeable;
    }

    /**
     * @param rechargeable
     *            the rechargeable to set
     */
    public void setRechargeable(boolean rechargeable) {
        this.rechargeable = rechargeable;
    }
}

Disc类：

/*
 * Copyright 2013-2015
 */
package com.jackie.codeproject.springrecipesnote.springioc.shop;

/**
 * Title: Disc.java 类的功能说明
 * 
 * @author jackie
 * @since Apr 14, 2013 8:18:30 PM
 * @version V1.0
 */
public class Disc extends Product {

    private int capacity;

    public Disc() {
        super();
    }

    public Disc(String name, double price) {
        super(name, price);
    }

    /**
     * @return the capacity
     */
    public int getCapacity() {
        return capacity;
    }

    /**
     * @param capacity
     *            the capacity to set
     */
    public void setCapacity(int capacity) {
        this.capacity = capacity;
    }
}

Bean配置文件：

<?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-3.2.xsd">

    <bean id="aaa" class="com.jackie.codeproject.springrecipesnote.springioc.shop.Battery">
	<property name="name" value="AAA" />
	<property name="price" value="2.5" />
	<property name="rechargeable" value="true" />
    </bean>
	
    <bean id="cdrw" class="com.jackie.codeproject.springrecipesnote.springioc.shop.Disc">
	<property name="name" value="CD-RW" />
	<property name="price" value="1.5" />
	<property name="capacity" value="700" />
    </bean>
</beans>

     如果没有指定<constructor-arg>元素，将会调用默认的不带参数的构造程序。然后对于每个<property>元素，Spring将通过setter方法注入值。前面的Bean配置相当于：  

      Product aaa = new Battery();

      aaa.setName("AAA");

      aaa.setPrice(2.5);

      aaa.setRechargeable(true);

      Product aaa = new Battery();

      aaa.setName("AAA");

      aaa.setPrice(2.5);

      aaa.setCapacity(700);

     相反，如果有一个或者多个<constructor-arg>元素，Spring将调用匹配参数最合适的构造程序。

     以下是测试函数：

/*
 * Copyright 2013-2015
 */
package com.jackie.codeproject.springrecipesnote.springioc.shop;

import org.junit.After;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * Title: ProductTest.java 类的功能说 测试类
 * 
 * @author jackie
 * @since Apr 14, 2013 8:31:45 PM
 * @version V1.0
 */
public class ProductTest {

    private ApplicationContext applicationContext;

    @Test
    public void testProduct() {
        applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
        Product aaa = (Product) applicationContext.getBean("aaa");
        Product cdrw = (Product) applicationContext.getBean("cdrw");
        System.out.println(aaa);
        System.out.println(cdrw);
    }

    @After
    public void after() {
        if (null != applicationContext) {
            applicationContext = null;
        }
    }
}