记录一下SpringMVC扫描注解包的配置

最近做了一个小项目,使用Spring4+SpringMVC+Hibernate5

但是整合完毕了之后,在页面上请求添加记录的时候发现无法开启事务,报错的信息如下:

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.HibernateException: Could not obtain transaction-synchronized Session for current thread

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:982) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at javax.servlet.http.HttpServlet.service(HttpServlet.java:707) ~[javax.servlet-api-3.1.0.jar:3.1.0]

at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) ~[javax.servlet-api-3.1.0.jar:3.1.0]

at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812) ~[jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669) ~[jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:201) ~[websocket-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) ~[jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) [jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577) [jetty-security-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) [jetty-servlet-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:215) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.Server.handle(Server.java:499) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:258) [jetty-server-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544) [jetty-io-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635) [jetty-util-9.2.22.v20170606.jar:9.2.22.v20170606]

at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555) [jetty-util-9.2.22.v20170606.jar:9.2.22.v20170606]

at java.lang.Thread.run(Thread.java:745) [na:1.8.0_77]

Caused by: org.hibernate.HibernateException: Could not obtain transaction-synchronized Session for current thread

at org.springframework.orm.hibernate5.SpringSessionContext.currentSession(SpringSessionContext.java:133) ~[spring-orm-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:465) ~[hibernate-core-5.2.11.Final.jar:5.2.11.Final]

at com.jiaoyiping.baseproject.base.BaseDaoImpl.getSession(BaseDaoImpl.java:31) ~[main/:na]

at com.jiaoyiping.baseproject.base.BaseDaoImpl.save(BaseDaoImpl.java:76) ~[main/:na]

at com.jiaoyiping.baseproject.diary.service.DiaryService.saveDiary(DiaryService.java:46) ~[main/:na]

at com.jiaoyiping.baseproject.diary.DiaryController.add(DiaryController.java:32) ~[main/:na]

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_77]

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_77]

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_77]

at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_77]

at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) ~[spring-web-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133) ~[spring-web-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.11.RELEASE.jar:4.3.11.RELEASE]

... 29 common frames omitted

原本以为是事务配置的问题,但是检查了一下,事务配置应该是正确的,后来使用Junit对service层进行单元测试的时候,发现,单元测试代码里边是可以开启事务的,也可以成功保存到数据库

所以,应该是SpringMVC和Spring容器结合的时候配置的问题,当时spring和springMVC里边都配置了一下扫描注解包的一行:

    <context:component-scan base-package="com.jiaoyiping"/>

Spring的容器和SpringMVC的容器应该是一对父子容器,如果都配置成这行代码的话,难道SpringMVC里边也会再重新加载一遍所有的bean吗?

合理的配置应该是Spring容器加载除了controller之外的其他的bean,而SpringMVC的容器加载Controller的bean,这样,各司其职,就不会互相影响,

在org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider类中,我找到了解析这一段配置的代码,

这个类有两个私有的属性

    private final List<TypeFilter> includeFilters = new LinkedList<TypeFilter>();

private final List<TypeFilter> excludeFilters = new LinkedList<TypeFilter>();

映射到配置文件的 include-filter 和 exclude-filter 属性上,我们可以通过在配置文件上配置 include-filter 和 exclude-filter来让容器处理哪些类型的注解和不扫描哪些类型的注解

值得一提的是,在ClassPathScanningCandidateComponentProvider的构造方法中,有一个useDefaultFilters,默认为true,会注册默认的注解类型到 include-filters

构造方法:

registerDefaultFilters()

这个useDefaultFilters可以通过配置文件中 context:component-scan 的use-default-filters 属性来进行控制.

所以,合理的配置应该是这样的:在Spring的配置文件里,排除掉@Controller注解,而在SpringMVC的配置文件里,include @Controller的注解,并且不适用默认的filter(因为适用默认的Filter的话,又会引入@Service和@Repository 等注解,因为在扫描@Component注解的时候,它们又会被扫描到)

正确的配置如下:

Spring中(排除了@Controller注解):

<context:component-scan base-package="com.jiaoyiping">
    <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
</context:component-scan>

SpringMVC中(配置mvc:annotation-driven/会扫描@RequestMapping等注解):

<mvc:annotation-driven/>
<context:component-scan base-package="com.jiaoyiping" use-default-filters="false">
    <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller" />
</context:component-scan>

这样配置完成之后,会各处理不同的注解,不会相互干扰,因为父子容器的关系,在controller里边可以使用@Autowired来注入service层或者dao层的bean,事务也不会出问题了