mvc：資源導致ClassCastException

Question

我有一個Spring MVC web應用程序應該提供靜態資源。 因此，我有以下Spring配置：

<mvc:resources location="/resources/" mapping="/resources/**"/> 

但是每個請求的資源導致同樣醜陋ClassCastException異常：

java.lang.ClassCastException: java.lang.String cannot be cast to org.springframework.core.io.Resource 
at org.springframework.web.servlet.resource.ResourceHttpRequestHandler.getResource(ResourceHttpRequestHandler.java:158) 
at org.springframework.web.servlet.resource.ResourceHttpRequestHandler.handleRequest(ResourceHttpRequestHandler.java:109) 
at org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter.handle(HttpRequestHandlerAdapter.java:49) 
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:900) 
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:827) 
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) 
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:778) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88) 
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at com.myproject.filter.SetP3PHeaderFilter.doFilter(SetP3PHeaderFilter.java:48) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at com.myproject.filter.SessionIdUrlFilter.disableDefaultURLEncoding(SessionIdUrlFilter.java:83) 
at com.myproject.filter.SessionIdUrlFilter.avoidSessionFixation(SessionIdUrlFilter.java:53) 
at com.myproject.filter.SessionIdUrlFilter.doFilter(SessionIdUrlFilter.java:42) 
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:185) 
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:151) 
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) 
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:929) 
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:405) 
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:269) 
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:515) 
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) 
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
at java.lang.Thread.run(Thread.java:619) 

我用的版本3.1.0.RELEASE和3.0.4試了一下.RELEASE的春天框架，並觀察到完全相同的行爲。

Answer 1

這是很奇怪的，但這個問題似乎是，我已經定義這樣的轉換服務：

<bean id="conversionService" class="org.springframework.format.support.FormattingConversionServiceFactoryBean"> 
    <property name="converters"> 
     <list> 
      <bean class="com.example.CustomConverter" /> 
     </list> 
    </property> 
</bean> 

這是在這裏引用：

<mvc:annotation-driven conversion-service="conversionService" /> 

原來如果我改變bean id與f不同。即cs它工作正常。這很奇怪，因爲在文檔和展示中使用了相同的ID。

Answer 2

在您的配置中，您可能會缺少mvc:annotation-driven，即註冊屬性編輯器將字符串轉換爲資源的那個，可能會導致您爲此錯誤消息。