[問題] 請問Spring的constructor injection

[jtorngl (透)]

        最近在接觸Spring，從IoC的設定開始看，並練習一個範例


        HelloBean.java

public class HelloBean {
    private String helloWord;

    public HelloBean() {
    }

    public HelloBean(String helloWorld) {
        this.helloWord = helloWord;
    }

    public String getHelloWord() {
        return helloWord;
    }

    public void setHelloWord(String helloWord) {
        this.helloWord = helloWord;
    }
}


        SpringDemo.java

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;

public class SpringDemo {
    public static void main(String[] args) {
        Resource rs = new FileSystemResource("beans-config.xml");
        BeanFactory factory = new XmlBeanFactory(rs);

        HelloBean hello = (HelloBean) factory.getBean("helloBean");
        System.out.println(hello.getHelloWord());
    }

}

        beans-config.xml

<?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:aop="http://www.springframework.org/schema/aop"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">

    <!-- type 2 IoC -> setter injection -->
    <!--
    <bean id="helloBean" class="HelloBean">
        <property name="helloWord" value="hello, Tony!"></property>
    </bean>
    -->

    <!-- type 3 IoC -> constructor injection -->
    <bean id="helloBean" class="HelloBean">
        <constructor-arg>
           <value>hello, May!</value>
        </constructor-arg>
    </bean>
</beans>


        編譯好的class檔和beans-config.xml放在同一個目錄(classes)下

D:\SpringDemo\Demo_01\classes>java -classpath .;..\lib\* SpringDemo
2010/7/27 下午 04:30:45
org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
資訊: Loading XML bean definitions from file [D:\SpringDemo\Demo_01\classes\beans-config.xml]
null

        改成setter injection時，是有把hello, Tony!注入helloWorld
        但是constructor injection時，helloWorld的值為null
        請問問題是在什麼地方呢

        另請問為什麼執行時，都要加入classes的路徑？
        HelloBean和SpringDemo的class檔案在同一個package下了

D:\SpringDemo\Demo_01\classes>java -classpath ..\lib\* SpringDemo -> ×

D:\SpringDemo\Demo_01\classes>java -classpath .;..\lib\* SpringDemo -> ○

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推 dwi2:1.因為你的兩個bean的id都叫helloBean,第2個bean改名字跑看看
→ jtorngl:我第一個bean註解了
推 dwi2:恩....HelloBean的constructor裡面拼字有點怪怪的