使用spring的p命名空间的布线属性不起作用

Question

我正在尝试使用spring的p命名空间连接属性。问题是我得到了“org.springframework.beans.factory.BeanDefinitionStoreException :( ...）cvc-complex-type.3.2.2：属性'p：instrument-ref'不允许出现在元素'bean'中。 “

请查看我的xml课程并告诉我我做错了什么。

performers.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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="guitar" class="com.competition.Guitar"></bean>

    <bean id="instrumentalist" class="com.competition.Instrumentalist"
    p:instrument-ref="guitar" p:song="some song">
    </bean>
</beans>

Instrumentalist.java：

package com.competition;

public class Instrumentalist implements Performer {

    private Instrument instrument;
    private String song;

    public Instrument getInstrument() {
        return instrument;
    }

    public void setInstrument(Instrument instrument) {
       this.instrument = instrument;
    }

    public String getSong() {
        return song;
    }

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

    public void perform() {
        System.out.println("Playing " + song);
        instrument.play();

    }

}

Guitar.java：

package com.competition;

public class Guitar implements Instrument {

    public void play() {
        System.out.println("play on guitar");
    }

}