Question

我是春天的新人。我在书中做了一个例子 - ＆＃34; Spring in Action 2＆＃34;。这个例子描述了如何编写bean并最终得到错误。请帮我解决这个问题。这是代码：

package com.my.quest;
public interface Instrument {
    void play();
}

package com.my.quest;
public class Piano implements Instrument {
    public Piano(){}
    @Override
    public void play() {
        System.out.println("text");
    }
}

package com.my.quest;
public interface Performer {
    void perform ();
}

package com.my.quest;
public class Instrumentalist implements Performer {

    private Instrument inst;
    private String song;

    public Instrumentalist() {
    }

    void setSong(String song){
        this.song = song;
    }

    void setInstrument(Instrument inst){
        this.inst = inst;
    }

    @Override
    public void perform() {
        System.out.println("Playing " + song);
        inst.play();
    }
}

bean名为 - 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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">

    <bean id="kenny" class="com.my.quest.Instrumentalist"> 
    <property name="song" value="Cage The Elephant – Shake Me Down" />
    <property name="inst" ref="piano"/>
    </bean>

    <bean id="piano" class="com.my.quest.Piano">
    </bean>

</beans>

我已经以这种方式进行了测试并且正在运行：

package com.my.quest;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class QuestStart {

    public static void main(String[] args) {    

        Instrument inst = new Piano();
        Instrumentalist in = new Instrumentalist();
        in.setInstrument(inst);
        in.setSong("Cage The Elephant – Shake Me Down");
        in.perform();
    }
}

结果：在控制台中键入消息 - ＆gt;玩凯奇大象 - 震撼我：文字

但如果我使用它：

 package com.my.quest;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;

    public class QuestStart {

        public static void main(String[] args) {    

          ApplicationContext ctx = new ClassPathXmlApplicationContext("com/my/quest/config.xml");
          Performer p = (Performer)ctx.getBean("kenny");
          p.perform();  
        }
    }

我收到此错误：

фев 08, 2015 11:25:51 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@7106e68e: startup date [Sun Feb 08 23:25:51 EET 2015]; root of context hierarchy
фев 08, 2015 11:25:52 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [com/my/quest/config.xml]
фев 08, 2015 11:25:52 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@256216b3: defining beans [kenny,piano]; root of factory hierarchy
фев 08, 2015 11:25:52 PM org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons
INFO: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@256216b3: defining beans [kenny,piano]; root of factory hierarchy
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'kenny' defined in class path resource [com/my/quest/config.xml]: Error setting property values; nested exception is org.springframework.beans.NotWritablePropertyException: Invalid property 'song' of bean class [com.my.quest.Instrumentalist]: Bean property 'song' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1361)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1086)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:580)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
    at com.my.quest.QuestStart.main(QuestStart.java:19)
Caused by: org.springframework.beans.NotWritablePropertyException: Invalid property 'song' of bean class [com.my.quest.Instrumentalist]: Bean property 'song' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:1031)
    at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:899)
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:76)
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:58)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1358)
    ... 13 more

下载了几个JAR：

org.springframework.context和context.support - 3.1.0.M2
org.springframework.asm - 3.1.0.M2
org.springframework.expression - 3.1.0.M2
org.springframework.beans - 3.1.0.M2
org.springframework.core - 3.1.0.M2
org.apache.common.logging

帮助，请告诉我我做错了什么。

Answer 1

setSong bean的public方法应为Instrumentalist：

public void setSong(String song) {

通常也应该有匹配的getSong方法。

得到了预先实例化的单身人士错误

1 个答案: