相关疑难解决方法(0)

从我在Java中使用线程的时间开始,我发现了这两种编写线程的方法:

用implements Runnable:

public class MyRunnable implements Runnable {
    public void run() {
        //Code
    }
}
//Started with a "new Thread(new MyRunnable()).start()" call

或者,用extends Thread:

public class MyThread extends Thread {
    public MyThread() {
        super("MyThread");
    }
    public void run() {
        //Code
    }
}
//Started with a "new MyThread().start()" call

这两个代码块有什么显着差异吗？

我有2个不同的Java项目,一个有2个类:dynamicbeans.DynamicBean2和dynamic.Validator.

在另一个项目中,我动态加载这两个类并将它们存储在一个 Object

class Form {
    Class beanClass;
    Class validatorClass;
    Validator validator;
}

然后我继续创建一个Validator对象validatorClass.newInstance()并使用它validator然后我创建一个bean对象并使用beanClass.newInstance()并将其添加到会话中.

portletRequest.setAttribute("DynamicBean2", bean);

在Form项目的生命周期中,我调用validator.validate()从会话中加载先前创建的bean对象(我​​正在运行Websphere Portal Server).当我尝试将此对象强制转换为DynamicBean2失败并出现ClassCastException时.

当我将对象拉回会话时使用

faces.getApplication().createValueBinding("#{DynamicBean2}").getValue(faces);

并使用.getClass()我得到检查它的类dynamicbeans.DynamicBean2.这是我想要将它强制转换为的类,但是当我尝试获取ClassCastException时.

我得到这个的原因是什么？

我还是Spring MVC的新手,在构建我的测试项目时,我从Tomcat日志中收到了这条消息:

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'divisionController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'adminService' must be of type [employee.service.impl.AdminServiceImpl], but was actually of type [$Proxy52]
    at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessPropertyValues(CommonAnnotationBeanPostProcessor.java:307)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106)
    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$1.getObject(AbstractBeanFactory.java:294)
    ...
Caused by: org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'adminService' must be of type [employee.service.impl.AdminServiceImpl], but was actually of type [$Proxy52]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:360)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)

我为用户和管理员提供了两个rolle服务:

package employee.service;

import …

我试图在Java中调试涉及ClassCastException的问题.为了解决这个问题,我需要知道当我从Object转换为特定类型时会发生什么.任何人都可以向我解释Java转换运算符如何在Java级别和JVM级别上运行？

有没有办法将Spring bean自动转换为应用程序上下文XML中定义的类？我想避免在两个位置放置关于bean的类型信息....在xml配置文件中以及在代码中作为强制转换.

例如,给定此配置文件

<bean id="bean-name" class="SimpleSpringBean"  scope="prototype">
    <property name="myValue" value="simple value"></property>
</bean>

我可以这样调用ApplicationContext.getBean("bean-name")以避免直接将返回类型转换为SimpleStringBean.我知道我也可以打电话ApplicationContext.getBean("bean-name", SimpleSpringBean.class)来避免演员本身,但我仍然有2个地方的类型信息.

看起来Spring可以获取类info(ApplicationContext.getType)或者从bean本身获取类型,但没有办法在没有程序员干预的情况下自动转换类型.