DispatchServlet

1.概述：

• • The DispatcherServlet is an actual Servlet (it inherits from the HttpServlet base class)
  •  它用于拦截用户请求，并且将请求交给相应的handler处理（即交给@Controller   @RequestMapping类来处理）

2.配置DispatchServlet，使得它能够拦截相应的请求 （也即URL mapping）     

　　　概述:

　　　　　　有多种方法可以使得DispatcherServlet能够拦截相应的URL请求（即拦截类似“/example/*”之类的请求）

　　    方法一，使用code-based configuration　　

• • • • /**
         * @author chen
         * @description 此类用于初始化spring web mvc中的DispatchServlet
         *                 使得"/example/*"之类的url请求可以被dispatchServlet拦截
         * */
        public class InitializeSpringMVC implements WebApplicationInitializer{
            @Override
            public void onStartup(ServletContext container) {
                ServletRegistration.Dynamic registration = container.addServlet("example", new DispatcherServlet());
                registration.setLoadOnStartup(1);
                registration.addMapping("/example/*");
            }
        
        }

        In the preceding example, all requests starting with /example will be handled by the DispatcherServlet instance named example.

      • WebApplicationInitializer is an interface provided by Spring MVC that ensures your code-based configuration is detected and automatically used to initialize any Servlet 3 container.

      • An abstract base class implementation of this interface named AbstractAnnotationConfigDispatcherServletInitializer makes it even easier to register the DispatcherServlet by simply specifying its servlet mapping and listing configuration classes - it’s even the recommended way to set up your Spring MVC application. See Code-based Servlet container initialization for more details.

　　  方法二，使用web.xml来配置URL mapping　　

• • • • <web-app>
            <servlet>
                <servlet-name>example</servlet-name>
                <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
                <load-on-startup>1</load-on-startup>
            </servlet>
        
            <servlet-mapping>
                <servlet-name>example</servlet-name>
                <url-pattern>/example/*</url-pattern>
            </servlet-mapping>
        
        </web-app>

        In the preceding example, all requests starting with /example will be handled by the DispatcherServlet instance named example.

        　　　　　　

Spring MVC------->version4.3.6-------->知识点------>DispatchServlet