How can I migrate from Spring 3.x to 5.x?

Question

I have a Spring 3 project and I want it to be migrated to Spring 5.

Now, I have web.xml in the project given below :

<servlet-mapping>
                    <servlet-name>mvc-dispatcher</servlet-name>
                    <url-pattern>/registrationapplication/*</url-pattern>
                </servlet-mapping>
                <servlet-mapping>
                    <servlet-name>mvc-dispatcher</servlet-name>
                    <url-pattern>/maintenance/lienholder/*</url-pattern>
                </servlet-mapping>
                <servlet-mapping>
                    <servlet-name>mvc-dispatcher</servlet-name>
                    <url-pattern>/login/*</url-pattern>
                </servlet-mapping>
                <servlet-mapping>
                    <servlet-name>mvc-dispatcher</servlet-name>
                    <url-pattern>/messagemap/*</url-pattern>
                </servlet-mapping>

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

            <context-param>
                    <param-name>contextConfigLocation</param-name>
                    <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value>
                </context-param>

Before migration, I have questions. These are as follows :

1. How would I be able to convert the below lines in web.xml to Java based configuration while migration from Spring 3.0 to Spring 5

2. Whether I need to read the mvc-dispatcher-servlet.xml or do I need to migrate java based configuration for converting mvc-dispatcher-servlet.xml as well in spring 5?

Answer 1

1.You don't need to change the web.xml for Spring 5. You may change the servlet version (if required).

It remains as it is :

A typical web.xml for Spring:

 <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
      <display-name>example</display-name>
      <servlet>
        <servlet-name>mvc-dispatcher</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
          <param-name>contextConfigLocation</param-name>
          <param-value>/WEB-INF/mvc-dispatcher-servlet.xml</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
      </servlet>
      <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
      </servlet-mapping>
      <!-- Custom Servlet Mapping-->
      <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/registrationapplication/*</url-pattern>
      </servlet-mapping>
      <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/maintenance/lienholder/*</url-pattern>
      </servlet-mapping>
      <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/login/*</url-pattern>
      </servlet-mapping>
      <servlet-mapping>
        <servlet-name>mvc-dispatcher</servlet-name>
        <url-pattern>/messagemap/*</url-pattern>
      </servlet-mapping>
    </web-app>

2. You can use Java-based configuration or xml-based configuration. Both are supported. You can still work with older configuration.

The Java-based configuration will be like this :

public class DispatcherServletConfig extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] { Configure.class };
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/", "/registrationapplication", "/login", "/messagemap", "/maintenance/lienholder"};
    }

}

@Configuration
@EnableWebMvc 
@ComponentScan(value = {"com.example"})
public class Configure {

    @Bean
    public InternalResourceViewResolver getInternalResourceViewResolver() {
        InternalResourceViewResolver resolver = new InternalResourceViewResolver();
        resolver.setPrefix("/WEB-INF/views/");
        resolver.setSuffix(".jsp");
        return resolver;
    }
}