在 Sakai 工具中使用 Jackson 作为带有 Spring MVC 的消息转换器的 ClassNotFoundException
ClassNotFoundException using Jackson as message converter with Spring MVC in a Sakai tool
我正在尝试使用 Spring MVC 创建 REST Web 服务。我使用 Spring MVC Maven archetype.
创建了一个准系统 Sakai 工具
我已经定义了我的 POJO，并希望 Spring 自动将它们转换为 JSON 并从我的控制器 return 它们。我创建了一个控制器：
@Controller
public class JSONController {
@RequestMapping(value = "/test", method = RequestMethod.GET)
public @ResponseBody
Test getJSON() {
return new Test;
}
}
当我添加对 Jackson 的依赖（我已经尝试过 v1 和 v2），并将 <mvn:annotation-driven> 和 <context:component-scan base-package="package.name" /> 添加到 web.xml 时，我立即得到这个 ClassDefNotFoundError:
Aug 06, 2015 3:01:04 PM org.apache.catalina.startup.HostConfig undeploy
INFO: Undeploying context [/test-app-tool]
2015-08-06 15:01:04,372 INFO ContainerBackgroundProcessor[StandardEngine[Catalina]] org.sakaiproject.util.ContextLoaderListener - Destroying Components in sakai.test-app
Aug 06, 2015 3:01:04 PM org.apache.catalina.startup.HostConfig deployWAR
INFO: Deploying web application archive {path-to}\tomcat\sakai-10.4\webapps\test-app-tool.war
2015-08-06 15:01:05,645 INFO localhost-startStop-2 org.sakaiproject.util.ToolListener - registering tools from resource: /tools/sakai.sakai-spring-maven-archetype.xml
2015-08-06 15:01:06,060 ERROR localhost-startStop-2 org.springframework.web.servlet.DispatcherServlet - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0': Cannot create inner bean '(inner bean)' of type [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter] while setting bean property 'messageConverters' with key [6]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#8': Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:282)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:126)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:353)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:154)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1387)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1128)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:626)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:599)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5229)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5516)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1083)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1880)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#8': Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1007)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:953)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:271)
... 37 more
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2585)
at java.lang.Class.getConstructor0(Class.java:2885)
at java.lang.Class.getDeclaredConstructor(Class.java:2058)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:78)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1000)
... 41 more
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.JsonProcessingException
at java.net.URLClassLoader.run(URLClassLoader.java:366)
at java.net.URLClassLoader.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 47 more
据我了解，如果在 class 路径中找到 Jackson，Spring 会将其激活为消息转换器（错误中引用的 MappingJackson2HttpMessageConverter bean）。但由于某种原因，它没有找到 JsonProcessingException class。我可以在 jackson-core-2.0.2.jar 的正确路径中看到这个 class 文件，它存在于我的 webapp 的 WEB-INF/lib 目录中。关于 Jackson 1 和 2 的相同 class，我得到了同样的错误。
奇怪的是，我在代码中导入和使用 Jackson 没有问题，所以依赖关系就在那里。我也在一个普通的 web 应用程序中使用了这种方法（没有任何 Sakai 的东西）。为什么不能 Spring 连接这个 bean？
我正在尝试使用 Spring MVC 创建 REST Web 服务。我使用 Spring MVC Maven archetype.
创建了一个准系统 Sakai 工具我已经定义了我的 POJO，并希望 Spring 自动将它们转换为 JSON 并从我的控制器 return 它们。我创建了一个控制器：
@Controller
public class JSONController {
@RequestMapping(value = "/test", method = RequestMethod.GET)
public @ResponseBody
Test getJSON() {
return new Test;
}
}
当我添加对 Jackson 的依赖（我已经尝试过 v1 和 v2），并将 <mvn:annotation-driven> 和 <context:component-scan base-package="package.name" /> 添加到 web.xml 时，我立即得到这个 ClassDefNotFoundError:
Aug 06, 2015 3:01:04 PM org.apache.catalina.startup.HostConfig undeploy
INFO: Undeploying context [/test-app-tool]
2015-08-06 15:01:04,372 INFO ContainerBackgroundProcessor[StandardEngine[Catalina]] org.sakaiproject.util.ContextLoaderListener - Destroying Components in sakai.test-app
Aug 06, 2015 3:01:04 PM org.apache.catalina.startup.HostConfig deployWAR
INFO: Deploying web application archive {path-to}\tomcat\sakai-10.4\webapps\test-app-tool.war
2015-08-06 15:01:05,645 INFO localhost-startStop-2 org.sakaiproject.util.ToolListener - registering tools from resource: /tools/sakai.sakai-spring-maven-archetype.xml
2015-08-06 15:01:06,060 ERROR localhost-startStop-2 org.springframework.web.servlet.DispatcherServlet - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0': Cannot create inner bean '(inner bean)' of type [org.springframework.http.converter.json.MappingJackson2HttpMessageConverter] while setting bean property 'messageConverters' with key [6]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#8': Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:282)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:126)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveManagedList(BeanDefinitionValueResolver.java:353)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:154)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1387)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1128)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:626)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:651)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:599)
at org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:665)
at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:518)
at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:459)
at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:136)
at javax.servlet.GenericServlet.init(GenericServlet.java:158)
at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1284)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1197)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1087)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:5229)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5516)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1083)
at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1880)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#8': Instantiation of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1007)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:953)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:487)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:271)
... 37 more
Caused by: java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonProcessingException
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2585)
at java.lang.Class.getConstructor0(Class.java:2885)
at java.lang.Class.getDeclaredConstructor(Class.java:2058)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:78)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1000)
... 41 more
Caused by: java.lang.ClassNotFoundException: com.fasterxml.jackson.core.JsonProcessingException
at java.net.URLClassLoader.run(URLClassLoader.java:366)
at java.net.URLClassLoader.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 47 more
据我了解，如果在 class 路径中找到 Jackson，Spring 会将其激活为消息转换器（错误中引用的 MappingJackson2HttpMessageConverter bean）。但由于某种原因，它没有找到 JsonProcessingException class。我可以在 jackson-core-2.0.2.jar 的正确路径中看到这个 class 文件，它存在于我的 webapp 的 WEB-INF/lib 目录中。关于 Jackson 1 和 2 的相同 class，我得到了同样的错误。
奇怪的是，我在代码中导入和使用 Jackson 没有问题，所以依赖关系就在那里。我也在一个普通的 web 应用程序中使用了这种方法（没有任何 Sakai 的东西）。为什么不能 Spring 连接这个 bean？