5

我正在使用spring MVC3，我发现如下代码：

@Controller
class IndexController
{
    @ModelAttribute("allTags")
    public List<ArticleTag> allTags()
    {
        return Collections.emptyList();
    }
}

有时会出现消息错误

（不总是）

SEVERE: Servlet.service() for servlet [appServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.util.List]: Specified class is an interface] with root cause
org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [java.util.List]: Specified class is an interface
        at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:101)
        at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.createAttribute(ModelAttributeMethodProcessor.java:132)
        at org.springframework.web.servlet.mvc.method.annotation.ServletModelAttributeMethodProcessor.createAttribute(ServletModelAttributeMethodProcessor.java:81)
        at org.springframework.web.method.annotation.ModelAttributeMethodProcessor.resolveArgument(ModelAttributeMethodProcessor.java:103)
        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:75)
        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:156)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:117)
        at org.springframework.web.method.annotation.ModelFactory.invokeModelAttributeMethods(ModelFactory.java:123)
        at org.springframework.web.method.annotation.ModelFactory.initModel(ModelFactory.java:97)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:614)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
        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:305)

有人说，List 是一个接口，请改用 ArrayList 或 LinkedList

但是，我的问题是，为什么上面的代码并不总是错误的？

当出现上述错误时，无论怎么刷新页面，错误一直持续，永远不会消失！但是，如果你重启tomcat，你有一个很好的机会来处理这个错误！如果没有出现上述错误，它永远不会出现util next tomcat重启！

与 int 或 Integer 类型的 @ModelAttribute 相同，它很可能会出错，但在某些主机上，它永远不会发生

4

1 回答 1

-1

更改代码如下

public ArticleTag allTags()

欲了解更多信息，请参阅以下链接

[ http://forum.spring.io/forum/spring-projects/data/nosql/724397-mapping-exception-with-mongodb-aggregation-framework][1]

另请参阅已修复的 Mongo 问题

[ https://jira.spring.io/browse/DATAMONGO-229]

于 2018-03-01T11:11:45.973 回答