2

我有一个基于AbstractJUnit4SpringContextTests类的简单 JUnit 测试：

@ContextConfiguration(locations = {
        "/test-spring-config.xml", "/test-databaseApplicationContext.xml",
        "/test-sharedApplicationContext.xml", "/test-dispatcher-servlet.xml"
})
public class TestTest extends AbstractJUnit4SpringContextTests {

    @Test
    public void testOneThing() {

    }
}

以及作为应用程序上下文的一部分加载的 bean：

<bean id="mySingleton" class="com.company.SingletonClass" />

这个单例，因为它在其他项目/位置中使用，有一个构造函数，确保在给定时间只有一个类的实例：

public class SingletonClass {
    private static SingletonClass instance = null;
    public SingletonClass() {
        if (instance != null) {
            throw new IllegalStateException("Highlander rules in effect.");
        }
        instance = this;
    }
}

但是，当我运行 JUnit 测试时，会遇到此异常。我从这个答案中了解到：Reuse spring application context across junit test classes

只要locations它们相同，就可以重用应用程序上下文。然而，情况似乎并非如此。这是 bean 实例化的两个位置：

第一的：

Thread [main] (Suspended (breakpoint at line 47 in SingletonClass)) 
    SingletonClass.<init>() line: 47    
    NativeConstructorAccessorImpl.newInstance0(Constructor, Object[]) line: not available [native method]   
    NativeConstructorAccessorImpl.newInstance(Object[]) line: 57    
    DelegatingConstructorAccessorImpl.newInstance(Object[]) line: 45    
    Constructor<T>.newInstance(Object...) line: 525 
    BeanUtils.instantiateClass(Constructor<T>, Object...) line: 147 
    CglibSubclassingInstantiationStrategy(SimpleInstantiationStrategy).instantiate(RootBeanDefinition, String, BeanFactory) line: 76    
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).instantiateBean(String, RootBeanDefinition) line: 990    
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBeanInstance(String, RootBeanDefinition, Object[]) line: 943   
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).doCreateBean(String, RootBeanDefinition, Object[]) line: 485 
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBean(String, RootBeanDefinition, Object[]) line: 456   
    AbstractBeanFactory$1.getObject() line: 294 
    DefaultListableBeanFactory(DefaultSingletonBeanRegistry).getSingleton(String, ObjectFactory) line: 225  
    DefaultListableBeanFactory(AbstractBeanFactory).doGetBean(String, Class<T>, Object[], boolean) line: 291    
    DefaultListableBeanFactory(AbstractBeanFactory).getBean(String) line: 193   
    DefaultListableBeanFactory.preInstantiateSingletons() line: 585 
    GenericApplicationContext(AbstractApplicationContext).finishBeanFactoryInitialization(ConfigurableListableBeanFactory) line: 913    
    GenericApplicationContext(AbstractApplicationContext).refresh() line: 464   
    GenericXmlContextLoader(AbstractGenericContextLoader).loadContext(MergedContextConfiguration) line: 103 
    GenericXmlContextLoader(AbstractGenericContextLoader).loadContext(MergedContextConfiguration) line: 1   
    DelegatingSmartContextLoader.loadContext(MergedContextConfiguration) line: 228  
    TestContext.loadApplicationContext() line: 124  
    TestContext.getApplicationContext() line: 148   
    DependencyInjectionTestExecutionListener.injectDependencies(TestContext) line: 109  
    DependencyInjectionTestExecutionListener.prepareTestInstance(TestContext) line: 75  
    TestContextManager.prepareTestInstance(Object) line: 321    
    SpringJUnit4ClassRunner.createTest() line: 211  
    SpringJUnit4ClassRunner$1.runReflectiveCall() line: 288 
    SpringJUnit4ClassRunner$1(ReflectiveCallable).run() line: 15    
    SpringJUnit4ClassRunner.methodBlock(FrameworkMethod) line: 290  
    SpringJUnit4ClassRunner.runChild(FrameworkMethod, RunNotifier) line: 231    
    SpringJUnit4ClassRunner(BlockJUnit4ClassRunner).runChild(Object, RunNotifier) line: 44  
    SpringJUnit4ClassRunner(ParentRunner<T>).runChildren(RunNotifier) line: 180 
    ParentRunner<T>.access$000(ParentRunner, RunNotifier) line: 41  
    ParentRunner$1.evaluate() line: 173 
    RunBefores.evaluate() line: 28  
    RunBeforeTestClassCallbacks.evaluate() line: 61 
    RunAfters.evaluate() line: 31   
    RunAfterTestClassCallbacks.evaluate() line: 71  
    SpringJUnit4ClassRunner(ParentRunner<T>).run(RunNotifier) line: 220 
    SpringJUnit4ClassRunner.run(RunNotifier) line: 174  
    JUnit4TestMethodReference(JUnit4TestReference).run(TestExecution) line: 50  
    TestExecution.run(ITestReference[]) line: 38    
    RemoteTestRunner.runTests(String[], String, TestExecution) line: 467    
    RemoteTestRunner.runTests(TestExecution) line: 683  
    RemoteTestRunner.run() line: 390    
    RemoteTestRunner.main(String[]) line: 197

第二：

Thread [main] (Suspended (breakpoint at line 47 in SingletonClass)) 
    SingletonClass$$EnhancerByCGLIB$$e8a4cc48(SingletonClass).<init>() line: 47 
    SingletonClass$$EnhancerByCGLIB$$e8a4cc48.<init>() line: not available  
    NativeConstructorAccessorImpl.newInstance0(Constructor, Object[]) line: not available [native method]   
    NativeConstructorAccessorImpl.newInstance(Object[]) line: 57    
    DelegatingConstructorAccessorImpl.newInstance(Object[]) line: 45    
    Constructor<T>.newInstance(Object...) line: 525 
    ReflectUtils.newInstance(Constructor, Object[]) line: 228   
    ReflectUtils.newInstance(Class, Class[], Object[]) line: 220    
    ReflectUtils.newInstance(Class) line: 216   
    Enhancer.createUsingReflection(Class) line: 643 
    Enhancer.firstInstance(Class) line: 538 
    Enhancer(AbstractClassGenerator).create(Object) line: 225   
    Enhancer.createHelper() line: 377   
    Enhancer.create() line: 285 
    Cglib2AopProxy.getProxy(ClassLoader) line: 201  
    ProxyFactory.getProxy(ClassLoader) line: 112    
    InfrastructureAdvisorAutoProxyCreator(AbstractAutoProxyCreator).createProxy(Class<?>, String, Object[], TargetSource) line: 476 
    InfrastructureAdvisorAutoProxyCreator(AbstractAutoProxyCreator).wrapIfNecessary(Object, String, Object) line: 362   
    InfrastructureAdvisorAutoProxyCreator(AbstractAutoProxyCreator).postProcessAfterInitialization(Object, String) line: 322    
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).applyBeanPostProcessorsAfterInitialization(Object, String) line: 407 
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).initializeBean(String, Object, RootBeanDefinition) line: 1461    
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).doCreateBean(String, RootBeanDefinition, Object[]) line: 519 
    DefaultListableBeanFactory(AbstractAutowireCapableBeanFactory).createBean(String, RootBeanDefinition, Object[]) line: 456   
    AbstractBeanFactory$1.getObject() line: 294 
    DefaultListableBeanFactory(DefaultSingletonBeanRegistry).getSingleton(String, ObjectFactory) line: 225  
    DefaultListableBeanFactory(AbstractBeanFactory).doGetBean(String, Class<T>, Object[], boolean) line: 291    
    DefaultListableBeanFactory(AbstractBeanFactory).getBean(String) line: 193   
    DefaultListableBeanFactory.preInstantiateSingletons() line: 585 
    GenericApplicationContext(AbstractApplicationContext).finishBeanFactoryInitialization(ConfigurableListableBeanFactory) line: 913    
    GenericApplicationContext(AbstractApplicationContext).refresh() line: 464   
    GenericXmlContextLoader(AbstractGenericContextLoader).loadContext(MergedContextConfiguration) line: 103 
    GenericXmlContextLoader(AbstractGenericContextLoader).loadContext(MergedContextConfiguration) line: 1   
    DelegatingSmartContextLoader.loadContext(MergedContextConfiguration) line: 228  
    TestContext.loadApplicationContext() line: 124  
    TestContext.getApplicationContext() line: 148   
    DependencyInjectionTestExecutionListener.injectDependencies(TestContext) line: 109  
    DependencyInjectionTestExecutionListener.prepareTestInstance(TestContext) line: 75  
    TestContextManager.prepareTestInstance(Object) line: 321    
    SpringJUnit4ClassRunner.createTest() line: 211  
    SpringJUnit4ClassRunner$1.runReflectiveCall() line: 288 
    SpringJUnit4ClassRunner$1(ReflectiveCallable).run() line: 15    
    SpringJUnit4ClassRunner.methodBlock(FrameworkMethod) line: 290  
    SpringJUnit4ClassRunner.runChild(FrameworkMethod, RunNotifier) line: 231    
    SpringJUnit4ClassRunner(BlockJUnit4ClassRunner).runChild(Object, RunNotifier) line: 44  
    SpringJUnit4ClassRunner(ParentRunner<T>).runChildren(RunNotifier) line: 180 
    ParentRunner<T>.access$000(ParentRunner, RunNotifier) line: 41  
    ParentRunner$1.evaluate() line: 173 
    RunBefores.evaluate() line: 28  
    RunBeforeTestClassCallbacks.evaluate() line: 61 
    RunAfters.evaluate() line: 31   
    RunAfterTestClassCallbacks.evaluate() line: 71  
    SpringJUnit4ClassRunner(ParentRunner<T>).run(RunNotifier) line: 220 
    SpringJUnit4ClassRunner.run(RunNotifier) line: 174  
    JUnit4TestMethodReference(JUnit4TestReference).run(TestExecution) line: 50  
    TestExecution.run(ITestReference[]) line: 38    
    RemoteTestRunner.runTests(String[], String, TestExecution) line: 467    
    RemoteTestRunner.runTests(TestExecution) line: 683  
    RemoteTestRunner.run() line: 390    
    RemoteTestRunner.main(String[]) line: 197

构造函数被调用两次的原因是什么，如何防止这种情况发生？虽然这些单例检查似乎确实给单元测试环境带来了麻烦，但它们过去在实际生产中作为一个很好的“硬”限制发挥了很好的作用。

4

1 回答 1

2

我认为原因是您的单例类没有公开 Spring 可用于其应用程序上下文的接口。Spring 的自动装配基于实现一个接口，该接口充当类的单例代理。但是，由于您的单例类是一个实际的类，因此 Spring 不能这样做，而是被迫使用 cglib（您在堆栈跟踪中看到）对您的类进行子类化。任何子类也必须调用超级构造函数，因此您会看到两次调用。

所以，简而言之：我认为 appcontext 不是这里的问题。如果您的类将公开并实现 Spring 可以使用其代理实现的实际接口，就像推荐的那样，我怀疑您不会得到您的异常。

于 2013-10-16T18:56:35.637 回答