在spring-mvc应用程序的开头运行一个类

Question

is it possible to run a class at the time of application starting in spring mvc i want to initialize a thread in that class ??

or is there any way..?

                public class MyServletContextListener implements Runnable {



            public void run() {

                while (true) {

                try {
                    System.out.println("Inside run()");
                    Thread.sleep(10000);
                } catch (Exception e) {
                    e.printStackTrace();
                }
                }


            }

            }

this output i got after adding ApplicationListener interface

            NFO: HHH000206: hibernate.properties not found
            Jul 24, 2017 8:42:33 PM org.hibernate.annotations.common.reflection.java.JavaReflectionManager <clinit>
            INFO: HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
            Jul 24, 2017 8:42:35 PM org.hibernate.dialect.Dialect <init>
            INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
            Jul 24, 2017 8:42:36 PM org.hibernate.engine.jdbc.env.internal.LobCreatorBuilderImpl useContextualLobCreation
            INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4

            Thread Started
            getApplicationName() : /Hibernate_webservice
            getId() : org.springframework.web.context.WebApplicationContext:/Hibernate_webservice
            getParent() : null
            getDisplayName() : Root WebApplicationContext


            Jul 24, 2017 8:42:38 PM org.springframework.web.context.ContextLoader initWebApplicationContext
            INFO: Root WebApplicationContext: initialization completed in 8880 ms
            Jul 24, 2017 8:42:38 PM org.apache.catalina.core.ApplicationContext log
            INFO: Initializing Spring FrameworkServlet 'appServlet'
            Jul 24, 2017 8:42:38 PM org.springframework.web.servlet.DispatcherServlet initServletBean
            INFO: FrameworkServlet 'appServlet': initialization started
            Jul 24, 2017 8:42:38 PM org.springframework.web.context.support.XmlWebApplicationContext prepareRefresh
            INFO: Refreshing WebApplicationContext for namespace 'appServlet-servlet': startup date [Mon Jul 24 20:42:38 IST 2017]; parent: Root WebApplicationContext
            Jul 24, 2017 8:42:38 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
            INFO: Loading XML bean definitions from ServletContext resource [/WEB-INF/spring-config.xml]
            Jul 24, 2017 8:42:38 PM org.springframework.context.support.PropertySourcesPlaceholderConfigurer loadProperties
            INFO: Loading properties file from class path resource [application.properties]
            Jul 24, 2017 8:42:38 PM org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor <init>
            INFO: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
            Jul 24, 2017 8:42:38 PM org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping registerHandlerMethod
            INFO: Mapped "{[/form],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.web.servlet.ModelAndView sample.test.TestController.method()
            Jul 24, 2017 8:42:39 PM org.hibernate.dialect.Dialect <init>
            INFO: HHH000400: Using dialect: org.hibernate.dialect.MySQL5Dialect
            Jul 24, 2017 8:42:39 PM org.hibernate.engine.jdbc.env.internal.LobCreatorBuilderImpl useContextualLobCreation
            INFO: HHH000423: Disabling contextual LOB creation as JDBC driver reported JDBC version [3] less than 4

            Thread Started
            getApplicationName() : /Hibernate_webservice
            getId() : org.springframework.web.context.WebApplicationContext:/Hibernate_webservice/appServlet
            getParent() : Root WebApplicationContext: startup date [Mon Jul 24 20:42:30 IST 2017]; root of context hierarchy
            getDisplayName() : WebApplicationContext for namespace 'appServlet-servlet'



            Thread Started
            getApplicationName() : /Hibernate_webservice
            getId() : org.springframework.web.context.WebApplicationContext:/Hibernate_webservice/appServlet
            getParent() : Root WebApplicationContext: startup date [Mon Jul 24 20:42:30 IST 2017]; root of context hierarchy
            getDisplayName() : WebApplicationContext for namespace 'appServlet-servlet'


            Jul 24, 2017 8:42:39 PM org.springframework.web.servlet.DispatcherServlet initServletBean
            INFO: FrameworkServlet 'appServlet': initialization completed in 1365 ms
            Jul 24, 2017 8:42:40 PM org.apache.coyote.AbstractProtocol start
            INFO: Starting ProtocolHandler ["http-nio-8082"]
            Jul 24, 2017 8:42:40 PM org.apache.coyote.AbstractProtocol start
            INFO: Starting ProtocolHandler ["ajp-nio-8011"]
            Jul 24, 2017 8:42:40 PM org.apache.catalina.startup.Catalina start
            INFO: Server startup in 19807 ms

Answer 1

Spring provides the ApplicationListener<ContextRefreshedEvent> interface and its onApplicationEvent(ContextRefreshedEvent event) hook.

For example:

@Component
public class MyServiceCreationListener implements ApplicationListener<ContextRefreshedEvent> {

    @Override
    public void onApplicationEvent(ContextRefreshedEvent event) {
      // do something on container startup
    }
}

Whatever you write in onApplicationEvent method will be executed once and only once when the Spring context is created.

If you find that this method is invoked more than once then you must have multiple ApplicationContext 's at play. If you inspect event.getApplicationContext() you'll likely see that each of them have a different id and displayName and you may be able to work out their origins. If yours is a Spring MVC application then you may have both a ContextLoaderListener and DispatcherServlet , both of these create their own ApplicationContext each of which fires a ContextRefreshedEvent .

If you want to determine which is the parent context you could try event.getApplicationContext().getParent() != null or you could toggle a class boolean within your ApplicationListener eg alreadyInitialised .

There's also Spring 4's SmartInitializingSingleton which might allow you to hook into context creation at a different level.

Answer 2

您可以添加应用程序侦听器（一个类实现了上下文侦听器接口）来轻松创建线程。如果要创建时间表，则可以使用石英或弹簧计时器

Answer 3

As of Spring 4.2 you can simply use the @EventListener annotation, listening for ContextRefreshedEvent :

@Component
public class StartupManager {

    @EventListener(ContextRefreshedEvent.class)
    public void doStartupStuff() {
        // ... up, up and away
    }

}

Answer 4

Create a simple Java thread by extending Thread, and managed by Spring's container via @Component. The bean scope must be “prototype“, so that each request will return a new instance, to run each individual thread.

PrintThread.java:

package com.mkyong.thread;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("prototype")
public class PrintThread extends Thread{

    @Override
    public void run() {

        System.out.println(getName() + " is running");
        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println(getName() + " is running");
    }

}

AppConfig.java:

package com.mkyong.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

@Configuration
@ComponentScan(basePackages="com.mkyong.thread")
public class AppConfig{
}

App.java:

package com.mkyong;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import com.mkyong.config.AppConfig;
import com.mkyong.thread.PrintThread;

public class App
{
    public static void main( String[] args )
    {

        ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);

        PrintThread printThread1 = (PrintThread) ctx.getBean("printThread");
        printThread1.setName("Thread 1");

        PrintThread printThread2 = (PrintThread) ctx.getBean("printThread");
        printThread2.setName("Thread 2");

        PrintThread printThread3 = (PrintThread) ctx.getBean("printThread");
        printThread3.setName("Thread 3");

        PrintThread printThread4 = (PrintThread) ctx.getBean("printThread");
        printThread4.setName("Thread 4");

        PrintThread printThread5 = (PrintThread) ctx.getBean("printThread");
        printThread5.setName("Thread 5");

        printThread1.start();
        printThread2.start();
        printThread3.start();
        printThread4.start();
        printThread5.start();

    }
}

Output – The order will be vary each time, this is thread :)

Thread 3 is running
Thread 2 is running
Thread 1 is running
Thread 5 is running
Thread 4 is running
Thread 2 is running
Thread 4 is running
Thread 5 is running
Thread 3 is running
Thread 1 is running

hope this is helpful :)