DispatcherServlet and web.xml in Spring Boot

Question

I\'m currently trying to move my project from Java EE to Spring Boot project. However, i\'ve been stucked and confused on the part with dispatcher servlet and web.xml and it

Answer 1

Spring-boot prefer annotations over xml based configurations, so in your case instead of using web.xml to configure the servlet, servlet-mapping, filter and filter mapping, you can use annotation based automatic bean creations to register beans.For that you need to :

• Convert the xml based mappings to annotation based mappings
• Create beans using @Bean annotations so that spring-boot will automatically take them up during component scan.

For reference: https://docs.spring.io/spring-boot/docs/current/reference/html/howto-traditional-deployment.html

• For registering filters and adding filter beans you can create a class annotate it with the @Configuration or @Component annotation and create bean of FilterRegistrationBean to register the filter.You can also create the beans of filter itself there by using @Bean annotation.

For example, the equivalent of the following xml based filter

  SomeUrlFilter
   com.company.SomeUrlFilter


    SomeUrlFilter
    /url/*
    
       paramName
       paramValue
    

The equivalent annotation based will be:

@Bean
public FilterRegistrationBean someUrlFilterRegistration() {

    FilterRegistrationBean registration = new FilterRegistrationBean();
    registration.setFilter(someUrlFilter());
    registration.addUrlPatterns("/url/*");
    registration.addInitParameter("paramName", "paramValue");
    registration.setName("Filter");
    registration.setOrder(1);
    return registration;
} 

@Bean(name = "someUrlFilter")
public Filter someUrlFilter() {
    return new SomeUrlFilter();
}

• Springboot still allows us to use the xml based configurations for example if you want to use the web.xml .For example :

Web.xml

    dispatcher
    org.springframework.web.servlet.DispatcherServlet
    
        contextConfigLocation
        /WEB-INF/spring/dispatcher.xml
    
    1



    dispatcher
    /

and in another file dispatcher.xml you can create beans as :

Note that Spring web.xml will usually live in src/main/webapp/WEB-INF.

You can refer : https://www.baeldung.com/register-servlet