为什么我需要 cglib (Spring AOP) 来拥有多个测试类？

Question

我有一个春季应用程序 我按如下方式创建测试类：

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = { "classpath:/META-INF/spring/applicationContext.xml" })
@TransactionConfiguration(defaultRollback = true)
@Transactional
public class MyTest {

}

当我尝试创建另一个测试类并尝试运行应用程序时，我在新测试类上收到以下异常：

ERROR [main] (TestContextManager.java:324) - Caught exception while allowing TestExecutionListener [org.springframework.test.context.support.DependencyInjectionTestExecut
r@22e85825] to prepare test instance [Testing.MyTest2@43f2f70a]
org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.
        at org.springframework.aop.framework.DefaultAopProxyFactory.createAopProxy(DefaultAopProxyFactory.java:67)
        at org.springframework.aop.framework.ProxyCreatorSupport.createAopProxy(ProxyCreatorSupport.java:104)
        at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:112)
        at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.createProxy(AbstractAutoProxyCreator.java:476)
        at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:362)
        at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:322)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1426)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:386)
        at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:111)
        at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:75)
        at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:321)
        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:220)
        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:301)
        at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:303)
        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:240)
        at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
        at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
        at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
        at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
        at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
        at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
        at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
        at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
        at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
        at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:180)
        at org.apache.maven.surefire.junit4.JUnit4TestSet.execute(JUnit4TestSet.java:62)
        at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.executeTestSet(AbstractDirectoryTestSuite.java:140)
        at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.execute(AbstractDirectoryTestSuite.java:127)
        at org.apache.maven.surefire.Surefire.run(Surefire.java:177)
        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 org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:345)
        at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:1009)

通过将 cglib 添加到我的类路径解决了此异常，但我想理解为什么多个测试类需要 cglib？

请指教，谢谢。

Answer 1

Spring 需要 CGLIB jar，因为它使用 CGLIB 来代理您的 bean。如果您在 applicationContext.xml 中将 spring 配置为使用此机制，或者 Spring 需要代理一个未实现接口的类，则会发生这种情况。 Spring 文档位于此处提供了非常清晰的解释。

为了使用 JDK 动态代理，请确保任何代理类都实现适当的接口，并且您不会通过配置强制 Spring 使用 CGLIB。

Answer 2

我的猜测是 spring 在运行时将其添加到您的类中，这就是为什么它需要 cglib 库（它用于字节码操作和代码注入，请参阅 此处）

Answer 3

Spring 肯定会为你的某些类使用代理机制。

但是，从 Spring 3.2 版本开始， CGLIB 源代码被重新打包 并默认添加到 spring-core 中，因此您无需手动将 CGLIB 库添加到类路径中。

顺便说一句，正如 spring 博客条目 Michael Isvy 和此问题报告指出，CGLIB 项目不再活跃。在未来的版本中，Spring 将默认使用 Javassist。