问题
I am creating an @Scheduled task to run every 5 seconds. As has been a problem in other questions, my task is running twice!
I have looked at other questions, and read the applicable documentation here, but I have not been able to figure out the problem.
I know that two seperate instances of my @Scheduled class are getting instantiated when I start my tomcat server. I have also figured out when they are instantiated in reference to my log file.
One associated with this log line :
INFO: Initializing Spring root WebApplicationContext
and another with this log line:
INFO: Initializing Spring FrameworkServlet 'servlet'
Here is the spring config file.
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:security="http://www.springframework.org/schema/security"
xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.1.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.2.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd">
<context:component-scan base-package="web.controllers"/>
<context:component-scan base-package="services"/>
<context:component-scan base-package="dao"/>
<context:component-scan base-package="scheduled"/>
<context:property-placeholder location="/WEB-INF/application.properties"/>
<mvc:annotation-driven/>
<mvc:default-servlet-handler/>
<task:annotation-driven />
And my simple java class:
package scheduled;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Service;
@Service
public class Notifier {
@Scheduled(fixedDelay = 5000)
public void notifyUsersOfBidItems() {
try {
System.out.println(this);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Also, I am using Spring 4.
EDIT: Adding web.xml
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
version="3.0">
<display-name>Archetype Created Web Application</display-name>
<servlet>
<servlet-name>servlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring_config.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>servlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring_config.xml</param-value>
</context-param>
<error-page>
<error-code>404</error-code>
<location>/error/notFound</location>
</error-page>
<error-page>
<error-code>403</error-code>
<location>/error/notFound</location>
</error-page>
<error-page>
<location>/error/internal</location>
</error-page>
<!-- Spring Security -->
<filter>
<filter-name>springSecurityFilterChain</filter-name>
<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
</filter>
<filter-mapping>
<filter-name>springSecurityFilterChain</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
回答1:
I believe this is caused by same config file being loaded twice in your web.xml
<servlet>
<servlet-name>servlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring_config.xml</param-value> <!-- FIRST -->
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/spring_config.xml</param-value> <!-- SECOND -->
</context-param>
EDIT To fix it:
Create another file servlet-servlet.xml (this will be picked up by the ServletDispatcher config by default since it matches the file by servlet name) The file will contain this:
<beans>
<context:component-scan base-package="web.controllers"/>
<mvc:annotation-driven/>
<mvc:default-servlet-handler/>
</beans>
Modify the original file (spring-config.xml):
<beans>
<task:annotation-driven />
<context:component-scan base-package="services"/>
<context:component-scan base-package="dao"/>
<context:component-scan base-package="scheduled"/>
<context:property-placeholder location="/WEB-INF/application.properties"/>
</beans>
Modify your web xml servlet config to following:
<servlet>
<servlet-name>servlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
回答2:
I also had this problem. I am using Spring 4. I have no xml configuration. Everything is configured with annotations and Java config.
I have a base configuration and a WebConfiguration. the error was caused by using @ComponentScan in both configurations. I removed component scan from base configuration.
@EnableWebMvc
@ComponentScan(basePackages = { "com.myservice" })
@Configuration
public class WebConfiguration extends WebMvcConfigurerAdapter {
@Bean
public UrlBasedViewResolver setupViewResolver() {
UrlBasedViewResolver resolver = new UrlBasedViewResolver();
resolver.setPrefix("/WEB-INF/jsp/");
resolver.setSuffix(".jsp");
resolver.setViewClass(JstlView.class);
return resolver;
}
@Override
public void configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) {
configurer.enable();
}
}
@Configuration
@EnableScheduling
//@ComponentScan(basePackages = { "com.myservice" })
@PropertySource("${myservice.properties.location:classpath:myservice.properties}")
public class BaseConfiguration {
@Autowired
Environment environment;
@Bean
public static PropertySourcesPlaceholderConfigurer properties() {
return new PropertySourcesPlaceholderConfigurer();
}
回答3:
solution : Quartz + Spring double execution java config
getServletConfigClasses()-> return null;
public static class MvcWebApplicationInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
@Override
protected Class<?>[] getRootConfigClasses() {
return new Class[]{WebConfig.class};
}
@Override
protected Class<?>[] getServletConfigClasses() {
return null;
}
@Override
protected String[] getServletMappings() {
return new String[]{"/"};
}
}
example code solution
来源：https://stackoverflow.com/questions/28652416/spring-scheduled-task-runs-twice