我正在使用Spring Boot和jOOQ创建一个用于数据库查询的Web应用程序 我现在正在将数据库交互移动到接口。
这是我的界面：
public interface DatabaseService {
public Result<UserRecord> testConnection();
}
这是我的实施。它与我以前在Controller本身中使用的方式相同，使用DslContext AutoWired和方法中的查询，因为它可以工作。
@Component
public class DatabaseServiceImpl implements DatabaseService {
private static Log log = LogFactory.getLog(DatabaseServiceImpl.class);
// Load the DSLContext to access the DB
@Autowired
@DB(DBs.MEDIATOR)
DSLContext dslContext;
public Result<UserRecord> testConnection() {
log.info("IN THE METHOD");
Result<UserRecord> result = this.dslContext.selectFrom(Tables.USER)
.fetch();
log.info("END OF METHOD: " + result.toString());
return result;
}
}
我要求从我的Controller执行此查询：
@Controller
public class OverviewController {
private static Log log = LogFactory.getLog(OverviewController.class);
public DatabaseService databaseService = new DatabaseServiceImpl();
@RequestMapping("/overview")
public String showConfigurationList(Model model) {
String foo = databaseService.testConnection().toString();
log.info("TEST: " + foo);
model.addAttribute("configurationsResult", getConfigurations());
return "overview";
}
}
但是当我执行它时，我得到一个NullPointerException：
java.lang.NullPointerException: null
at nl.nazza.mediator.deviceconfigurator.service.DatabaseServiceImpl.testConnection(DatabaseServiceImpl.java:29) ~[classes/:na]
at nl.nazza.mediator.deviceconfigurator.controllers.OverviewController.showConfigurationList(OverviewController.java:47) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_66-internal]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_66-internal]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_66-internal]
at java.lang.reflect.Method.invoke(Method.java:497) ~[na:1.8.0_66-internal]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:221) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:114) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:963) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:897) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:622) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) ~[spring-webmvc-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:230) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) ~[tomcat-embed-websocket-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:317) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:115) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:169) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:158) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:121) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:331) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:214) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:177) ~[spring-security-web-4.1.1.RELEASE.jar:4.1.1.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:346) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:262) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:87) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) ~[spring-web-4.3.2.RELEASE.jar:4.3.2.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:165) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) ~[tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:108) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:522) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:349) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:1110) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:785) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1425) [tomcat-embed-core-8.5.4.jar:8.5.4]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-8.5.4.jar:8.5.4]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_66-internal]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_66-internal]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-8.5.4.jar:8.5.4]
at java.lang.Thread.run(Thread.java:745) [na:1.8.0_66-internal]
现在我很困惑，因为它在控制器中时起作用，但在移动到接口及其实现时却没有。我确信它一定是简单的，我完全没有了，所以我希望你们能找到我在这里出错的地方。
答案 0 :(得分：1)
用
替换public DatabaseService databaseService = new DatabaseServiceImpl();
@Autowired
DatabaseService databaseService;
使用DatabaseServiceImpl代替@Service
@Component也是一件好事。