How can I register a secondary servlet with Spring Boot?

Question

I have an extra servlet I need to register in my application. However with Spring Boot and its Java Config, I can\'t just add servlet mappings in a web.xml file

Answer 1

Also available in the BeanDefinitionRegistryPostProcessor

package bj;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletRegistrationBean;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@SpringBootApplication
class App implements BeanDefinitionRegistryPostProcessor {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        registry.registerBeanDefinition("myServlet", new RootBeanDefinition(ServletRegistrationBean.class,
                () -> new ServletRegistrationBean<>(new HttpServlet() {
                    @Override
                    protected void service(HttpServletRequest req, HttpServletResponse resp) throws IOException {
                        resp.getWriter().write("hello world");
                    }
                }, "/foo/*")));
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
    }
}