Spring strategy learning notes (1.03) -- call constructor to create Bean

Generally, If you specify the class attribute for a bean, the Spring IoC container is required to call the constructor to create a bean.

As follows, there is a product class, which has two sub-classes: Battery and disc.

Product class:

/** Copyright 2013-2015 */package COM. jackie. codeproject. springrecipesnote. springioc. shop;/*** title: product. java * product abstract class ** @ author Jackie * @ since APR 14,201 3 8:09:49 * @ version V1.0 */public abstract class product {private string name; private double price; Public Product () {}/*** <p> title: </P> * <p> constructor with parameters </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 class:

/** Copyright 2013-2015 */package COM. jackie. codeproject. springrecipesnote. springioc. shop;/*** title: Battery. java class function description ** @ author Jackie * @ since APR 14,201 3 8:14:26 * @ 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 class:

/** Copyright 2013-2015 */package COM. jackie. codeproject. springrecipesnote. springioc. shop;/*** title: disc. java class function description ** @ author Jackie * @ since APR 14,201 3 8:18:30 * @ 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 configuration file:

<?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>

If the <constructor-Arg> element is not specified, the default constructor without parameters is called. For each <property> element, spring injects the value through the setter method.The bean configuration above is equivalent:

      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);

On the contrary, if one or more <constructor-Arg> elements exist, spring will call the most appropriate constructor that matches the parameters.

The following are test functions:

/** 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 class function description test class ** @ author Jackie * @ since APR 14,201 3 8:31:45 * @ version V1.0 */public class producttest { Private 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 ;}}}