我写的是hibernate+spring应用。
应用程序启动后(但在首次使用之前)我想检查数据库状态。
如果状态良好 - 跳过逻辑
如果状态不好 - 执行使状态良好的逻辑。
你能猜出这个问题的最佳实践吗？
Debojit Saikia更新
如果我写这段代码:
@Configuration
public class UiConfig {
@Bean
public AppListener getMyListener(){
AppListener appListener = new AppListener();
System.out.println();
System.out.println();
System.out.println(" appListener method ");
System.out.println();
System.out.println();
return appListener;
}
}
class AppListener implements ApplicationListener<ContextRefreshedEvent> {
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
System.out.println();
System.out.println();
System.out.println(" hello AppListener");
System.out.println();
System.out.println();
}
}
我在控制台看到下一个登录:
21.10.2013 18:46:05 org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: C:\Program Files\Java\jdk1.6.0_37\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\Program Files\Java\jdk1.6.0_37\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\QuickTime\QTSystem\;C:\Program Files\TortoiseSVN\bin;C:\Program Files\Microsoft SQL Server\110\Tools\Binn\;C:\Program Files (x86)\Microsoft SQL Server\110\Tools\Binn\;C:\Program Files\Microsoft SQL Server\110\DTS\Binn\;C:\Program Files (x86)\Microsoft SQL Server\110\Tools\Binn\ManagementStudio\;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\PrivateAssemblies\;C:\Program Files (x86)\Microsoft SQL Server\110\DTS\Binn\;%ANT_HOME%/bin;C:\Program Files\Apache Software Foundation\apache-maven-3.0.5\\bin;C:\Program Files\Apache Software Foundation\apache-ant-1.9.0/bin;.
21.10.2013 18:46:06 org.apache.tomcat.util.digester.SetPropertiesRule begin
WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.jee.server:ui' did not find a matching property.
21.10.2013 18:46:06 org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
21.10.2013 18:46:06 org.apache.coyote.AbstractProtocol init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
21.10.2013 18:46:06 org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 762 ms
...
INFO : org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/security_config.xml]
INFO : org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
INFO : org.springframework.beans.factory.support.DefaultListableBeanFactory - Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@77be91c8: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalPersistenceAnnotationProcessor,candidateDao,eventDaoImpl,eventStatusDao,eventTypeDao,noteDao,skillDao,userDao,vacancyDao,candidateService,eventService,utilService,vacancyService,baseMenuController,candidateMenuController,provider,eventMenuController,homeController,uiConfig,vacancyMenuController,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,transactionManager,dataSource,sessionFactory,entryPoint,org.springframework.security.filterChains,org.springframework.security.filterChainProxy,org.springframework.security.web.PortMapperImpl#0,org.springframework.security.web.PortResolverImpl#0,org.springframework.security.config.authentication.AuthenticationManagerFactoryBean#0,org.springframework.security.authentication.ProviderManager#0,org.springframework.security.web.context.HttpSessionSecurityContextRepository#0,org.springframework.security.web.authentication.session.SessionFixationProtectionStrategy#0,org.springframework.security.web.savedrequest.HttpSessionRequestCache#0,org.springframework.security.web.access.expression.DefaultWebSecurityExpressionHandler#0,org.springframework.security.access.vote.AffirmativeBased#0,org.springframework.security.web.access.intercept.FilterSecurityInterceptor#0,org.springframework.security.web.access.DefaultWebInvocationPrivilegeEvaluator#0,org.springframework.security.authentication.AnonymousAuthenticationProvider#0,org.springframework.security.web.authentication.www.BasicAuthenticationEntryPoint#0,org.springframework.security.web.authentication.UsernamePasswordAuthenticationFilter#0,org.springframework.security.userDetailsServiceFactory,org.springframework.security.web.DefaultSecurityFilterChain#0,org.springframework.security.authentication.DefaultAuthenticationEventPublisher#0,org.springframework.security.authenticationManager,org.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessor,messageSource,getMyListener]; root of factory hierarchy
appListener method
hello AppListener
INFO : org.springframework.web.context.ContextLoader - Root WebApplicationContext: initialization completed in 4544 ms
21.10.2013 18:46:21 org.apache.catalina.core.ApplicationContext log
INFO: Initializing Spring FrameworkServlet 'appServlet'
INFO : org.springframework.web.servlet.DispatcherServlet - FrameworkServlet 'appServlet': initialization started
INFO : org.springframework.web.context.support.XmlWebApplicationContext - Refreshing WebApplicationContext for namespace 'appServlet-servlet': startup date [Mon Oct 21 18:46:21 MSK 2013]; parent: Root WebApplicationContext
...
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/addVacancy],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.web.servlet.ModelAndView com.epam.hhsystem.web.controllers.VacancyMenuController.addVacancy(com.epam.hhsystem.model.vacancy.Vacancy,org.springframework.validation.BindingResult,org.springframework.ui.Model,org.springframework.web.servlet.mvc.support.RedirectAttributes)
INFO : org.springframework.web.servlet.handler.SimpleUrlHandlerMapping - Mapped URL path [/resources/**] onto handler 'org.springframework.web.servlet.resource.ResourceHttpRequestHandler#0'
appListener method
hello AppListener
hello AppListener
INFO : org.springframework.web.servlet.DispatcherServlet - FrameworkServlet 'appServlet': initialization completed in 770 ms
21.10.2013 18:46:22 org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-bio-8080"]
21.10.2013 18:46:22 org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-bio-8009"]
21.10.2013 18:46:22 org.apache.catalina.startup.Catalina start
INFO: Server startup in 16053 ms
此监听器在我运行 tomcat 后调用了更多 1 次。
我希望它只调用一次
最佳答案
我会使用(假设你在 servlet 上下文环境中)监听器，我会通过实现 javax.servlet.ServletContextListener 创建一个监听器并将它们作为最后一个监听器。它将被称为最后一个监听器(也取决于服务器，检查服务器的文档)。在听众中，我会确保状态良好。好处是，它在向服务器发出任何请求之前被调用。 Web 服务器/Web 容器为您保证这一点。
例子:
public class MyContextListener implements ServletContextListener {
public void contextInitialized(ServletContextEvent sce){
//do your work here
}
}
在网络 xml 中:
<listener>
<listener-class>com.my.MyContextListener</listener-class>
</listener>
关于java - hibernate + Spring 应用程序。在使用数据库之前添加逻辑，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19495956/