《Spring In Action》 读书笔记（2） -- bean装配

接上一篇

property的用法

property标签内部的属性也是ref和value，跟 constructor-arg用法无异，所以这里结合 集合 装配来说

property标签跟 constructor-arg 区别在于 后者是找构造方法，前者是找类的字段。先上代码

先写一个Instruments（乐器）接口

package spring.ioc03;

public interface Instruments {
public void play();
}

再写三个乐器，实现Instruments接口

package spring.ioc03;

public class Cello implements Instruments {

@Override
public void play() {
System.out.print("大提琴 ");
}

}

package spring.ioc03;

public class Piano implements Instruments {

@Override
public void play() {
System.out.print("钢琴 ");
}

}

package spring.ioc03;

public class Violin implements Instruments {

@Override
public void play() {
System.out.print("小提琴 ");
}

}

最后写一个Pan（演奏者），他分别用list，map，set三种集合类型来保存自己会的乐器。还有一个performance方法，展示自己会的乐器。

package spring.ioc03;

import java.util.List;
import java.util.Map;
import java.util.Set;

public class Pan {
private List<Instruments> instrumentsList;
private Map<String, Instruments> instrumentsMap;
private Set<Instruments> instrumentsSet;

public void performance() {

System.out.print("list我会 ");
for (Instruments instrument : instrumentsList)
instrument.play();
System.out.println();

System.out.print("map我会 ");
for (Instruments instrument : instrumentsMap.values())
instrument.play();
System.out.println();

System.out.print("set我会 ");
for (Instruments instrument : instrumentsSet)
instrument.play();
}

public List<Instruments> getInstrumentsList() {
return instrumentsList;
}

public void setInstrumentsList(List<Instruments> instrumentsList) {
this.instrumentsList = instrumentsList;
}

public Map<String, Instruments> getInstrumentsMap() {
return instrumentsMap;
}

public void setInstrumentsMap(Map<String, Instruments> instrumentsMap) {
this.instrumentsMap = instrumentsMap;
}

public Set<Instruments> getInstrumentsSet() {
return instrumentsSet;
}

public void setInstrumentsSet(Set<Instruments> instrumentsSet) {
this.instrumentsSet = instrumentsSet;
}

}

最后看一下spring的配置文件, property 标签的name属性对应类的 某个字段，比如instrumentsList,instrumentsSet，instrumentsMap，它会在spring装配bean的时候自动为这些字段赋值（通过字段的set方法），然后集合的装配方法见下面的配置。以达到装配pan的目的。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:util="http://www.springframework.org/schema/util" xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-4.0.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.0.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd"

default-lazy-init="true">

<description>Spring Configuration</description>

<bean id="pan" class="spring.ioc03.Pan">
<!-- list -->
<property name="instrumentsList">
<list>
<bean class="spring.ioc03.Cello"></bean>
<bean class="spring.ioc03.Piano"></bean>
<bean class="spring.ioc03.Violin"></bean>
</list>
</property>
<!-- Set -->
<property name="instrumentsSet">
<set>
<bean class="spring.ioc03.Cello"></bean>
<bean class="spring.ioc03.Piano"></bean>
<bean class="spring.ioc03.Violin"></bean>
</set>
</property>
<!-- Map -->
<property name="instrumentsMap">
<map>
<entry key="1" >
<bean class="spring.ioc03.Cello"></bean>
</entry>
<entry key="2" >
<bean class="spring.ioc03.Piano"></bean>
</entry>
<entry key="3" >
<bean class="spring.ioc03.Violin"></bean>
</entry>
</map>
</property>
</bean>

</beans>

最后的单元测试

/**
* ioc03
* 装配List,map,set
*/
@Test
public void test4() {
ApplicationContext context = new ClassPathXmlApplicationContext("ioc03.xml");
spring.ioc03.Pan pan = (spring.ioc03.Pan) context.getBean("pan");
pan.performance();
}

输出结果为

list我会 大提琴 钢琴 小提琴

map我会 大提琴 钢琴 小提琴

set我会 大提琴 钢琴 小提琴