基于Spring代码的配置 - IllegalArgumentException：需要ServletContext

Question

我在这里找到了一个基于代码的100％弹簧配置的例子：

http://docs.spring.io/spring/docs/3.1.x/javadoc-api/org/springframework/web/WebApplicationInitializer.html

内容：

public class MyWebAppInitializer implements WebApplicationInitializer {

@Override
public void onStartup(ServletContext container) {
  // Create the 'root' Spring application context
  AnnotationConfigWebApplicationContext rootContext =
    new AnnotationConfigWebApplicationContext();
  rootContext.register(AppConfig.class);

  // Manage the lifecycle of the root application context
  container.addListener(new ContextLoaderListener(rootContext));

  // Create the dispatcher servlet's Spring application context
  AnnotationConfigWebApplicationContext dispatcherContext =
    new AnnotationConfigWebApplicationContext();
  dispatcherContext.register(DispatcherConfig.class);

  // Register and map the dispatcher servlet
  ServletRegistration.Dynamic dispatcher =
    container.addServlet("dispatcher", new DispatcherServlet(dispatcherContext));
  dispatcher.setLoadOnStartup(1);
  dispatcher.addMapping("/");
}

}

在上面的示例中，他们在注册配置类后从未调用refresh（）。 但是API说 - 必须调用refresh（）才能使上下文完全处理新类。 所以我在每个寄存器语句

中添加了refresh（）

rootContext.register(AppConfig.class);
rootContext.refresh();

dispatcherContext.register(DispatcherConfig.class);
dispatcherContext.refresh();

结果：

SEVERE: ContainerBase.addChild: start: 
org.apache.catalina.LifecycleException: Failed to start component    [StandardEngine[Catalina].StandardHost[localhost].StandardContext[]]
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:726)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:702)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:699)
at org.apache.catalina.startup.HostConfig.manageApp(HostConfig.java:1647)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:465)
at org.apache.catalina.mbeans.MBeanFactory.createStandardContext(MBeanFactory.java:415)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.apache.tomcat.util.modeler.BaseModelMBean.invoke(BaseModelMBean.java:300)
at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.invoke(DefaultMBeanServerInterceptor.java:819)
at com.sun.jmx.mbeanserver.JmxMBeanServer.invoke(JmxMBeanServer.java:801)
at javax.management.remote.rmi.RMIConnectionImpl.doOperation(RMIConnectionImpl.java:1487)
at javax.management.remote.rmi.RMIConnectionImpl.access$300(RMIConnectionImpl.java:97)
at javax.management.remote.rmi.RMIConnectionImpl$PrivilegedOperation.run(RMIConnectionImpl.java:1328)
at javax.management.remote.rmi.RMIConnectionImpl.doPrivilegedOperation(RMIConnectionImpl.java:1420)
at javax.management.remote.rmi.RMIConnectionImpl.invoke(RMIConnectionImpl.java:848)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:322)
at sun.rmi.transport.Transport$1.run(Transport.java:177)
at sun.rmi.transport.Transport$1.run(Transport.java:174)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:173)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:556)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:811)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:670)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:724)
    Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'defaultServletHandlerMapping' defined in class path resource [org/springframework/web/servlet/config/annotation/DelegatingWebMvcConfiguration.class]: Instantiation of bean failed; nested exception is org.springframework.beans.factory.BeanDefinitionStoreException: Factory method [public org.springframework.web.servlet.HandlerMapping org.springframework.web.servlet.config.annotation.WebMvcConfigurationSupport.defaultServletHandlerMapping()] threw exception; nested exception is java.lang.IllegalArgumentException: A ServletContext is required to configure default servlet handling
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:592)

但如果我删除refresh（）（显然）它工作正常（我使用Tomcat 8.0） 最后，我不完全理解是否必须在这样的代码中使用refresh（）。如果不是 - 我什么时候应该使用它？

Answer 1

在您的情况下，这仅对传递给ApplicationContext的{​​{1}}很重要。那个DispatcherServlet构造函数表示

  

给定的Web应用程序上下文可能会或可能尚未刷新。如果   它还没有被刷新（推荐的方法），然后是   将发生以下情况：

     

  
• 如果给定的上下文还没有父级，则根应用程序上下文将被设置为父级。
  
• 如果尚未为给定的上下文分配ID，则会为其分配一个
  
• DispatcherServlet和ServletContext个对象将被委派给应用程序上下文
  
• ServletConfig将被称为
  
• 通过指定的任何postProcessWebApplicationContext   “contextInitializerClasses”init-param或通过   将应用setContextInitializers属性。
  如果上下文实现ApplicationContextInitializers ，则会调用
• refresh()   

     

如果上下文已经刷新，则以上都不会   在用户已执行这些操作的假设下发生   （或不）根据他们的特定需求。

因此对于ConfigurableApplicationContext，您必须执行以下操作

DispatcherServlet

这对于AnnotationConfigWebApplicationContext dispatcherContext = new AnnotationConfigWebApplicationContext(); dispatcherContext.register(DispatcherConfig.class); // will take care of calling refresh() on the ApplicationContext ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", new DispatcherServlet(dispatcherContext)); 配置是必需的，因为由于DispatcherServlet（或等效的@EnableWebMvc）而生成的某些bean需要<mvc:annotation-driven>和/或{{1 Servlet容器提供的对象。

根上下文不应该具有这样的依赖性，因此可以安全地执行

ServletContext

请注意，您可以通过将ServletConfig类作为参数传递给其构造函数来创建AnnotationConfigWebApplicationContext rootContext = new AnnotationConfigWebApplicationContext(); rootContext.register(AppConfig.class); rootContext.refresh(); 对象。