java - Spring @Scheduled 任务运行两次

Question

我正在创建一个每 5 秒运行一次的 @Scheduled 任务。正如其他问题中的问题一样，我的任务运行了两次!

我查看了其他问题，并阅读了适用的文档 here , 但我一直没能找出问题所在。

我知道当我启动我的 tomcat 服务器时，我的 @Scheduled 类的两个独立实例正在被实例化。我还弄清楚了它们何时根据我的日志文件实例化。

与此日志行关联的一个:

INFO: Initializing Spring root WebApplicationContext

还有一个日志行:

INFO: Initializing Spring FrameworkServlet 'servlet'

这是spring配置文件。

<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 />

还有我的简单 java 类:

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();
    }

}
}

此外，我正在使用 Spring 4。

编辑:添加 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>

Answer 1

我相信这是由于同一个配置文件在您的 web.xml 中被加载了两次

<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>

编辑要修复它:

创建另一个文件 servlet-servlet.xml(这将默认由 ServletDispatcher 配置获取，因为它通过 servlet 名称匹配文件)该文件将包含以下内容:

<beans>
    <context:component-scan base-package="web.controllers"/>
    <mvc:annotation-driven/>
    <mvc:default-servlet-handler/>
</beans>

修改原文件(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>

将您的 web xml servlet 配置修改为以下内容:

<servlet>
    <servlet-name>servlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>1</load-on-startup>
</servlet>