Run a Java class from Spring startup

问题

I am using Java8 and Spring4.3.1.

I have a Java/Spring application hosting RESTfult services accessed by browser and mobile app clients. Second, I have written a Chat Server that listens for events (socket.io) from the clients. This Chat Server is running from the classes main method.

The Chat Server class has a main method that I want to run, and allow to listen for events when my Spring application starts. Is this possible?

If I run the main myself, it works, but I want it to start up when I start my Wildfly server that loads the Spring application.

Or is there a better approach? Should the Chat Server not be running from the main method?

I have the following code:

package com.jobs.spring.configuration;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration.Dynamic;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

public class WebAppInitializer implements WebApplicationInitializer {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.register(AppConfig.class);
        ctx.setServletContext(servletContext);
        Dynamic dynamic = servletContext.addServlet("rest", new DispatcherServlet(ctx));
        dynamic.addMapping("/*");
        dynamic.setLoadOnStartup(1);

        try {
            com.jobs.spring.chat.Server chatServer = new com.jobs.spring.chat.Server();
            chatServer.run(null);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

and

public class Server implements CommandLineRunner {

    private static final String SERVER = "localhost";
    private static final Integer PORT = 3700;

    @Override
    public void run(String... args) throws Exception {
        main(args);
    }

    public static void main(String[] args) {
...

and get the following error:

18:47:08,142 ERROR [org.jboss.msc.service.fail] (ServerService Thread Pool -- 66) MSC000001: Failed to start service jboss.undertow.deployment.default-server.default-host./jbosswildfly: org.jboss.msc.service.StartException in service jboss.undertow.deployment.default-server.default-host./jbosswildfly: java.lang.NoClassDefFoundError: Failed to link com/jobs/spring/chat/Server (Module "deployment.jbosswildfly.war:main" from Service Module Loader): org/springframework/boot/CommandLineRunner

Caused by: java.lang.NoClassDefFoundError: Failed to link com/jobs/spring/chat/Server (Module "deployment.jbosswildfly.war:main" from Service Module Loader): org/springframework/boot/CommandLineRunner

回答1:

You could deploy your chat server in Wildfly, by extending SpringBootServletInitializer, instead of launching it from a main.

Documentation: howto-create-a-deployable-war-file

@SpringBootApplication
public class SpringBootApp extends SpringBootServletInitializer{

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder builder) {
        return builder.sources(SpringBootApp.class);
    }

    //public static void main(String[] args){
    //    new SpringApplicationBuilder()
    //    .sources(SpringBootApp.class)
    //    .run(args);
    //}
}

Change the artifact produced to war, and deploy it normally in wildfly:

<project>
    <packaging>war</packaging>
    ...
<project>

You may have to exclude tomcat, which is automatically imported with spring-boot-starter-web:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Spring provided a Spring Boot example of a pom.xml for wildfly: spring-boot-deployment-test-wildfly

来源：https://stackoverflow.com/questions/39233115/run-a-java-class-from-spring-startup

标签

java

Spring

spring-boot

war

wildfly