在开发过程中使用@Autowired注解遇到问题产生的一些想法
1. 问题 #
在开发过程中，别人使用了实现类注入，然后一直报错，找了好久原因，现用以下例子说明一下。
准备两个接口（AnarkhService、InvokeService）和两个实现类（AnarkhServiceImpl、InvokeServiceImpl），其中InvokeServiceImpl是要注入AnarkhServiceImpl或AnarkhService的类。
1.1 第一种情况：只有自己的方法 #
AnarkhService：
public interface AnarkhService {
String testFun();
}
AnarkhServiceImpl：
import java.sql.Timestamp;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import com.neusoft.agileggfw.dao.business.api.s.xmzjjg.b.BanklogDao;
import com.neusoft.agileggfw.entity.xmzjjg.api.support.b.Banklog;
import com.neusoft.agileggfw.service.xmzjjg.api.xmzjjg.service.AnarkhService;
@Service
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
public String testFun() {
return "sucess";
}
}
InvokeService：
public interface InvokeService {
}
InvokeServiceImpl：
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.neusoft.agileggfw.service.xmzjjg.api.xmzjjg.service.InvokeService;
@Service
public class InvokeServiceImpl implements InvokeService{
@Autowired
private AnarkhServiceImpl anarkhServiceImpl;
}
此时，程序启动是ok的。
编写controller对testFun()方法进行调用（此时controller中是使用@Autowired将AnarkhService注入的）：
@Controller
@RequestMapping(value="/a/a/")
public class WwaaAct {
@Autowired
private AnarkhService anarkhService;
@ResponseBody
@RequestMapping(value="report/anarkhTest.html", method = RequestMethod.POST, produces = { "text/html;charset=UTF-8" })
public String anarkhTest(){
anarkhService.testFun();
return "sucess";
}
}
结果：程序启动sucess，调用sucess。
1.2 第二种情况：既有自己的方法也有事务增强（事务增强方法用private） #
AnarkhServiceImpl：
@Service
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
public String testFun() {
insertBanklog("1");
return "sucess";
}
@Transactional
private void insertBanklog(String CCTransCode) {
Banklog banklog = new Banklog();
banklog.setCctranscode(CCTransCode);
banklogDao.save(banklog);
}
}
结果：程序启动sucess，能进debugger，调用fail。
报了No Session found for current thread的错：
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.hibernate.HibernateException: No Session found for current thread
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:965)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829)
at com.neusoft.agileweb2.mvc.internal.BundleDispatcherServlet.service(BundleDispatcherServlet.java:54)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.sensitive.internal.SensitiveCharFilter.doFilter(SensitiveCharFilter.java:36)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:155)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:65)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:38)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.hibernate.HibernateException: No Session found for current thread
at org.springframework.orm.hibernate4.SpringSessionContext.currentSession(SpringSessionContext.java:97)
at org.hibernate.internal.SessionFactoryImpl.getCurrentSession(SessionFactoryImpl.java:1041)
at com.neusoft.agileweb2.database.api.PlatformDao.save(PlatformDao.java:214)
at com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl.insertBanklog(AnarkhServiceImpl.java:29)
at com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl.testFun(AnarkhServiceImpl.java:21)
at com.neusoft.agileggfw.ww.internal.a.a.WwaaAct.anarkhTest(WwaaAct.java:172)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:685)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:919)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953)
... 72 more
1.3 第三种情况：既有自己的方法也有事务增强（事务增强方法用public） #
AnarkhServiceImpl：
@Service
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
public String testFun() {
insertBanklog("1");
return "sucess";
}
@Transactional
public void insertBanklog(String CCTransCode) {
Banklog banklog = new Banklog();
banklog.setCctranscode(CCTransCode);
banklogDao.save(banklog);
}
}
结果：程序启动sucess，不能进debugger，调用fail。
报了No qualifying bean of type的错：
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'invokeServiceImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.InvokeServiceImpl.anarkhServiceImpl; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:298)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1148)
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$1.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)
at com.neusoft.agileweb2.core.internal.bundle.BundleBeanFactory.getBean(BundleBeanFactory.java:69)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:636)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:934)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at com.neusoft.agileweb2.core.internal.bundle.BundleBeanFactory.findAutowireCandidates(BundleBeanFactory.java:42)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:864)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:779)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:498)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:295)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1148)
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$1.getObject(AbstractBeanFactory.java:293)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:191)
at com.neusoft.agileweb2.core.internal.bundle.BundleBeanFactory.getBean(BundleBeanFactory.java:69)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1119)
at org.springframework.web.method.HandlerMethod.createWithResolvedBean(HandlerMethod.java:219)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(AbstractHandlerMethodMapping.java:240)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(AbstractHandlerMethodMapping.java:56)
at org.springframework.web.servlet.handler.AbstractHandlerMapping.getHandler(AbstractHandlerMapping.java:297)
at org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1085)
at org.springframework.web.servlet.DispatcherServlet.getHandler(DispatcherServlet.java:1070)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:891)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829)
at com.neusoft.agileweb2.mvc.internal.BundleDispatcherServlet.service(BundleDispatcherServlet.java:54)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.sensitive.internal.SensitiveCharFilter.doFilter(SensitiveCharFilter.java:36)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:155)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:65)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:38)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.InvokeServiceImpl.anarkhServiceImpl; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:526)
at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:295)
... 107 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:997)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:867)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:779)
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:498)
... 109 more
1.4 第四种情况：既有自己的方法也有事务增强（事务增强方法用private）,在自己方法上加上事务注解或者在类上加事务注解 #
AnarkhServiceImpl：
@Service
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
@Transactional
public String testFun() {
insertBanklog("1");
return "sucess";
}
@Transactional
private void insertBanklog(String CCTransCode) {
Banklog banklog = new Banklog();
banklog.setCctranscode(CCTransCode);
banklogDao.save(banklog);
}
}
或：
@Service
@Transactional
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
public String testFun() {
insertBanklog("1");
return "sucess";
}
@Transactional
private void insertBanklog(String CCTransCode) {
Banklog banklog = new Banklog();
banklog.setCctranscode(CCTransCode);
banklogDao.save(banklog);
}
}
结果与第三种情况一致。
1.5 第五种情况：既有自己的方法也有事务增强（事务增强方法用private），但controller中对AnarkhService没使用@Autowired注入，而是直接new了一个对象 #
@Controller
@RequestMapping(value="/a/a/")
public class WwaaAct {
@ResponseBody
@RequestMapping(value="report/anarkhTest.html", method = RequestMethod.POST, produces = { "text/html;charset=UTF-8" })
public String anarkhTest(){
AnarkhService anarkhService = new AnarkhServiceImpl();
anarkhService.testFun();
return "sucess";
}
}
结果：程序启动sucess，能进debugger，调用fail。
报了空指针异常：
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:965)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:855)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:829)
at com.neusoft.agileweb2.mvc.internal.BundleDispatcherServlet.service(BundleDispatcherServlet.java:54)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:155)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.sensitive.internal.SensitiveCharFilter.doFilter(SensitiveCharFilter.java:36)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:65)
at com.neusoft.agileweb2.core.api.filter.CorsFilter.doFilter(CorsFilter.java:38)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:521)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1096)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:674)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
at com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl.insertBanklog(AnarkhServiceImpl.java:29)
at com.neusoft.agileggfw.service.xmzjjg.internal.xmzjjg.service.impl.AnarkhServiceImpl.testFun(AnarkhServiceImpl.java:21)
at com.neusoft.agileggfw.ww.internal.a.a.WwaaAct.anarkhTest(WwaaAct.java:202)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:745)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:685)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:919)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:851)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:953)
... 72 more
经过debugger可以看到，这种情况注入的dao层是null：
1.6 正确做法：如果不涉及对实现类增强，如事务、日志等，可以用@Autowired对实现类进行注入；但是如果涉及到实现类增强，就必须用@Autowired对接口进行注入。遂为了方便记忆，使用@Autowired注入时统一使用接口进行注入。 #
controller中不能使用new，第五种情况仍不行。
InvokeServiceImpl：
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.neusoft.agileggfw.service.xmzjjg.api.xmzjjg.service.AnarkhService;
import com.neusoft.agileggfw.service.xmzjjg.api.xmzjjg.service.InvokeService;
@Service
public class InvokeServiceImpl implements InvokeService{
@Autowired
private AnarkhService anarkhService;
}
AnarkhServiceImpl类中调用dao层方法的方法也要加上事务注解，不然报No Session found for current thread的错
@Service
public class AnarkhServiceImpl implements AnarkhService{
@Autowired
private BanklogDao banklogDao;
@Override
@Transactional
public String testFun() {
insertBanklog("1");
return "sucess";
}
@Transactional
private void insertBanklog(String CCTransCode) {
Banklog banklog = new Banklog();
banklog.setCctranscode(CCTransCode);
banklogDao.save(banklog);
}
}
2. 结论与分析 #
2.1 结论 #
分两种情况来说：
- 如果只是单纯的数据注入，是可以直接注入实现类的。
- 如果对实现类进行了增强，如事务、日志等，只能注入接口。
2.2 分析 #
首先要明确一点，像事务、日志等这种对实现类的增强都是通过AOP动态代理来实现的。AOP的原理就是动态代理，动态代理分为两种：一种是基于JDK的动态代理，这种是基于实现类的实现；一种是基于Cglib的动态代理，这种是基于子类的实现。
Spring默认使用的是JDK动态代理，对实现类对象做增强得到的增强类与实现类是兄弟关系，所以不能用实现类接收增强类对象，只能用接口接收。
//接口：IAnarkh
//实现类：AnarkhImpl
//增强类：AnarkhImplProxy
AnarkhImpl anarkhImpl = new AnarkhImpl();
//通过JDKProxyFactory创建代理对象
JDKProxyFactory factory = new JDKProxyFactory(anarkhImpl);
AnarkhImplProxy anarkhImplProxy = factory.createProxy();//这个增强类对象anarkhImplProxy只能强转为IAnarkh，而不能转为AnarkhImpl，因为JDK代理得到的AnarkhImplProxy类与AnarkhImpl是兄弟关系而非父子
因此，如果是直接注入被增强的实现类，其代理对象不会有被增强的内容（事务、日志等），因此会报错。
3. 扩展 #
3.1 @Autowired注入原理 #
@Autowired是Spring的注解，@Autowired默认先按照byType，如果发现找到多个bean，则改为按照byName方式比对，如果还有多个bean，就会报出异常。
在controller中获取实例的过程：使用@Autowired，程序在Spring的容器中查找类型是AnarkhService的bean，刚好找到有且只有一个此类型的bean，即anarkhServiceImpl，所以就把anarkhServiceImpl自动装配到controller的实例anarkhService中，anarkhService其实就是增强的（如果实现类有增强的话）AnarkhServiceImpl实例。
注：
byName 通过参数名 自动装配，如果一个bean的name 和另外一个bean的 property 相同，就自动装配。
byType 通过参数的数据类型自动自动装配，如果一个bean的数据类型和另外一个bean的property属性的数据类型兼容，就自动装配。
3.2 一个接口多个实现类的注入情况 #
例子代码：
//接口
public interface AnarkhService{
void test();
}
//实现1
@Service
public class AnarkhServiceImpl1 implements AnarkhService{
@Override
public String test() {
return "AnarkhServiceImpl1";
}
}
//实现2
@Service
public class AnarkhServiceImpl2 implements AnarkhService{
@Override
public String test() {
return "AnarkhServiceImpl2";
}
}
多个实现类的话可以通过一下两种方式来指定具体使用哪一种实现：
1.通过指定bean的名字来明确到底要实例哪一个类
@Autowired 需要结合@Qualifier来使用，如下：
@Autowired
@Qualifier("anarkhServiceImpl1")
//注意此处指定的anarkhServiceImpl1中的a是小写，因为Spring在装配bean的时候，如果没有指定，会把类名的首字母小写作为bean的name
private AnarkhService anarkhService;
2.通过在实现类是添加@Primary注解来指定默认加载类
@Service
@Primary
public class AnarkhServiceImpl2 implements AnarkhService{
@Override
public String test() {
return "AnarkhServiceImpl2";
}
}
这样如果在使用@Autowired获取实例时，如果不指定bean的名字，就会默认获取AnarkhServiceImpl2的bean，如果指定了bean的名字则以指定的为准。
3.3 @Autowired的使用范围 #
Autowired作用范围：
- 构造器
- 方法
- 参数
- 成员变量
- 注解
3.3.1 成员变量 #
在成员变量上使用@Autowired注解，这种方式是平时使用最多的场景：
@Service
public class UserService {
@Autowired
private IUser user;
}
3.3.2 构造器 #
在构造器上使用@Autowired注解：
@Service
public class UserService {
private IUser user;
@Autowired
public UserService(IUser user) {
this.user = user;
System.out.println("user:" + user);
}
}
注意：在构造器上加@Autowired注解，实际上还是使用了@Autowired装配方式，并非构造器装配。
3.3.3 方法 #
在普通方法上加@Autowired注解：
@Service
public class UserService {
@Autowired
public void test(IUser user) {
user.say();
}
}
Spring会在项目启动的过程中，自动调用一次加了@Autowired注解的方法，我们可以在该方法上做一些初始化的工作。
也可以在setter方法上使用@Autowired注解：
@Service
public class UserService {
private IUser user;
@Autowired
public void setUser(IUser user) {
this.user = user;
}
}
3.3.4 参数 #
可以在构造器的入参上加@Autowired注解：
@Service
public class UserService {
private IUser user;
public UserService(@Autowired IUser user) {
this.user = user;
System.out.println("user:" + user);
}
}
也可以在非静态方法的入参上加@Autowired注解：
@Service
public class UserService {
public void test(@Autowired IUser user) {
user.say();
}
}
3.3.5 注解 #
在注解上使用@Autowired不多。
3.4 @Autowired自动装配多个实例 #
上面举的例子都是通过@Autowired自动装配单个实例，但是它也能完成对多个实例的装配：
//IUser类
public interface IUser {
void say();
}
//User1类
@Service
public class User1 implements IUser{
@Override
public void say() {
}
}
//User2类
@Service
public class User2 implements IUser{
@Override
public void say() {
}
}
//UserService类
@Service
public class UserService {
@Autowired
private List<IUser> userList;
@Autowired
private Set<IUser> userSet;
@Autowired
private Map<String, IUser> userMap;
public void test() {
System.out.println("userList:" + userList);
System.out.println("userSet:" + userSet);
System.out.println("userMap:" + userMap);
}
}
//UController类
@RequestMapping("/u")
@RestController
public class UController {
@Autowired
private UserService userService;
@RequestMapping("/test")
public String test() {
userService.test();
return "success";
}
}
调用接口后：
从上图中看出：userList、userSet和userMap都打印出了两个元素，说明@Autowired会自动把相同类型的IUser对象收集到集合中。
3.5 常见的@Autowired装配失败原因 #
3.5.1 没有加@Service注解 #
在类上面忘了加@Controller、@Service、@Component、@Repository等注解，spring就无法完成自动装配的功能，例如：
public class UserService {
@Autowired
private IUser user;
public void test() {
user.say();
}
}
3.5.2 注入Filter或Listener #
web应用启动的顺序是：listener->filter->servlet。
下面案例则是在Filter使用了@Autowired报错的例子：
public class UserFilter implements Filter {
@Autowired
private IUser user;
@Override
public void init(FilterConfig filterConfig) throws ServletException {
user.say();
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
}
@Override
public void destroy() {
}
}
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean filterRegistrationBean() {
FilterRegistrationBean bean = new FilterRegistrationBean();
bean.setFilter(new UserFilter();
bean.addUrlPatterns("/*");
return bean;
}
}
程序在启动的时候就会报错：
可以看到tomcat无法正常启动。这是因为：SpringMVC的启动是在DispatchServlet里面做的，而它是在listener和filter之后执行的。如果我们想在listener和filter里面@Autowired某个bean，肯定是不行的，因为filter初始化的时候，此时bean还没有初始化，无法自动装配。
如果在工作当中真的需要这样做（在Filter或者Listener中使用@Autowired），可以使用WebApplicationContextUtils.getWebApplicationContext获取当前的ApplicationContext，再通过它获取到bean实例：
public class UserFilter implements Filter {
private IUser user;
@Override
public void init(FilterConfig filterConfig) throws ServletException {
ApplicationContext applicationContext = WebApplicationContextUtils.getWebApplicationContext(filterConfig.getServletContext();
this.user = ((IUser)(applicationContext.getBean("user1"));
user.say();
}
@Override
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
}
@Override
public void destroy() {
}
}
3.5.3 注解未被@ComponentScan扫描 #
通常情况下，@Controller、@Service、@Component、@Repository、@Configuration等注解，是需要通过@ComponentScan注解扫描，收集元数据的。
但是，如果没有加@ComponentScan注解，或者@ComponentScan注解扫描的路径不对，或者路径范围太小，会导致有些注解无法收集，到后面无法使用@Autowired完成自动装配的功能。
有个好消息是，在springboot项目中，如果使用了@SpringBootApplication注解，它里面内置了@ComponentScan注解的功能。
3.5.4 循环依赖问题 #
如果A依赖于B，B依赖于C，C又依赖于A，这样就形成了一个死循环。
spring的bean默认是单例的，如果单例bean使用@Autowired自动装配，大多数情况，能解决循环依赖问题。
但是如果bean是多例的，会出现循环依赖问题，导致bean自动装配不了。
还有有些情况下，如果创建了代理对象，即使bean是单例的，依然会出现循环依赖问题。