Question

我使用spring通过bean创建对象。现在我尝试使用aop来创建相同的对象，并且我得到$ Proxy无法转换为SaleRoom异常。

之前的xml是：

<?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/spring-aop-2.5.xsd"
xmlns:context="http://www.springframework.org/schema/context/spring-context-2.5.xsd"
xmlns:flow="http://www.springframework.org/schema/webflow-config/spring-webflow-config- 1.0.xsd"
xmlns:jm s="http://www.springframework.org/schema/jms/spring-jms-2.5.xsd"
xmlns:jee="http://www.springframework.org/schema/jee/spring-jee-2.5.xsd"
xmlns:lang="http://www.springframework.org/schema/lang/spring-lang-2.5.xsd"
xmlns:osgi="http://www.springframework.org/schema/osgi/spring-osgi.xsd"
xmlns:tx="http://www.springframework.org/schema/tx/spring-tx-2.5.xsd"
xmlns:util="http://www.springframework.org/schema/util/spring-util-2.5.xsd"
xmlns:p="http://www.springframework.org/schema/p"

xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/aop/spring-aop-2.5.xsd     http://www.springframework.org/schema/aop/spring-aop-2.5.xsd/spring-spring-aop-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/context/spring-context-2.5.xsd     http://www.springframework.org/schema/context/spring-context-2.5.xsd/spring-spring-context-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/webflow-config/spring-webflow-config-1.0.xsd     http://www.springframework.org/schema/webflow-config/spring-webflow-config-1.0.xsd/spring-spring-webflow-config-1.0.xsd-2.5.xsd
http://www.springframework.org/schema/jms/spring-jms-2.5.xsd     http://www.springframework.org/schema/jms/spring-jms-2.5.xsd/spring-spring-jms-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/jee/spring-jee-2.5.xsd     http://www.springframework.org/schema/jee/spring-jee-2.5.xsd/spring-spring-jee-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/lang/spring-lang-2.5.xsd     http://www.springframework.org/schema/lang/spring-lang-2.5.xsd/spring-spring-lang-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/osgi/spring-osgi.xsd     http://www.springframework.org/schema/osgi/spring-osgi.xsd/spring-spring-osgi.xsd-2.5.xsd
http://www.springframework.org/schema/tx/spring-tx-2.5.xsd     http://www.springframework.org/schema/tx/spring-tx-2.5.xsd/spring-spring-tx-2.5.xsd-2.5.xsd
http://www.springframework.org/schema/util/spring-util-2.5.xsd     http://www.springframework.org/schema/util/spring-util-2.5.xsd/spring-spring-util-2.5.xsd-2.5.xsd
">
<bean id="sale01" class="application.common.entities.BidRoom">
<property name="itemId" value="0001"/>
<property name="lifeTime" value="15"/>
</bean>
</beans>

我使用以下代码创建销售：

    ApplicationContext context = new FileSystemXmlApplicationContext(SalesManager.getSalesSourceFile());
    SaleRoom saleRoom;
    List<String> salesNames = new LinkedList<String>();
    List<SaleRoom> allSales = new LinkedList<SaleRoom>();

    // Get all sales id's for beans
    NodeList salesNodeList = salesDoc.getElementsByTagName("bean");

    for (int i = 0; i < salesNodeList.getLength(); i++) {
        Node nNode = salesNodeList.item(i);
        salesNames.add(((Element) nNode).getAttribute("id").toString());
    }

    for (String saleName : salesNames) {
        if(saleName.contains("sale")) {
            saleRoom = (SaleRoom) context.getBean(saleName);
            allSales.add(saleRoom);
        }
    }

    return allSales;

这是新的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"
           xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

    <aop:aspectj-autoproxy>
        <aop:include name="logSettersCalls"/>
    </aop:aspectj-autoproxy>
    <bean id="logSettersCalls" class="application.logging.aop.LogSettersCalls"/>

    <bean id="sale01" class="application.common.entities.BidRoom">
        <constructor-arg index="0" type="int" value="0001"/>
        <constructor-arg index="1" type="int" value="15"/>
    </bean>
</beans>

Aspect日志记录类：

@Aspect
public class LogSettersCalls {
   @Pointcut("execution(void set*(*))")
    public void setMethod() {}

    @Before("setMethod()")
    public void logSetterCall(JoinPoint theJoinPoint) {
        String methodName = theJoinPoint.getSignature().getName();
        Object newValue = theJoinPoint.getArgs()[0];
        Object theObject = theJoinPoint.getTarget();
        System.out.println("The method " + methodName + " is called on object " 
                + theObject + " with the value " + newValue);
    }
}

我使用相同的代码通过aop创建bean。我明白了线程“main”中的异常java.lang.ClassCastException：$ Proxy11无法强制转换为application.common.entities.SaleRoom

抛出异常的行： saleRoom =（SaleRoom）context.getBean（saleName）;

任何帮助将不胜感激。谢谢。

Answer 1

您的SaleRoom类是否实现了某些界面？如果是，那么你应该在代码中使用接口而不是类：

ISaleRoom saleRoom = (ISaleRoom) context.getBean(saleName);

因为如果你的bean实现了一些接口，那么Spring默认会根据这个接口创建代理。

这是a good article about proxy creation in Spring.

如果要为目标类创建代理，也可以更改Spring AOP的代理机制。这被描述为here in reference documentation。

ClassCastException $ Proxy无法强制转换为使用aop

1 个答案: