异常，BeanFactory not initialized or already closed

求助错误，BeanFactory not initialized or already closed

junit4测试报错

java.lang.IllegalStateException: BeanFactory not initialized or already closed - call 'refresh' before accessing beans via the ApplicationContext
at org.springframework.context.support.AbstractRefreshableApplicationContext.getBeanFactory(AbstractRefreshableApplicationContext.java:153)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:880)
at com.test.testUserService.testAdd(testUserService.java:16)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at junit.framework.TestCase.runTest(TestCase.java:164)
at junit.framework.TestCase.runBare(TestCase.java:130)
at junit.framework.TestResult$1.protect(TestResult.java:110)
at junit.framework.TestResult.runProtected(TestResult.java:128)
at junit.framework.TestResult.run(TestResult.java:113)
at junit.framework.TestCase.run(TestCase.java:120)
at junit.framework.TestSuite.runTest(TestSuite.java:228)
at junit.framework.TestSuite.run(TestSuite.java:223)
at org.junit.internal.runners.OldTestClassRunner.run(OldTestClassRunner.java:35)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)


package com.test;

import junit.framework.TestCase;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.model.User;
import com.service.UserService;（省略了包的导入）

public class testUserService extends TestCase {

public void testAdd(){
ApplicationContext ctx = new ClassPathXmlApplicationContext();

UserService service = (UserService)ctx.getBean("bean.xml");

User user = new User();

user.setName("a");
  user.setPassword("b");
service.add(user);
}
}

<?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-2.5.xsd">

  <bean id="u" class="com.DAOimpl.UserDAOimpl">
  <!-- collaborators and configuration for this bean go here -->
  </bean>

  <bean id="UserService" class="com.service.UserService">
  <property name="UserDao" ref="u">
  </bean>

  <!-- more bean definitions go here -->

</beans>



------解决方案--------------------

探讨

ApplicationContext ctx = new ClassPathXmlApplicationContext();

UserService service = (UserService)ctx.getBean("bean.xml");