SPRING IN ACTION 第4版笔记-第七章Advanced Spring MVC-001- DispatcherServlet的高级配置(ServletRegistration.Dynamic、WebApplicationInitializer)

一、

1.如想在DispatcherServlet在Servlet容器中注册后自定义一些操作，如开启文件上传功能，则可重写通过AbstractAnnotationConfigDispatcherServletInitializer 的customizeRegistration() 来实现

 //  After  AbstractAnnotation ConfigDispatcherServletInitializer registers  DispatcherServlet with the servlet
 //  container, it calls the  customizeRegistration() method, passing in the  Servlet-
 //  Registration.Dynamic that resulted from the servlet registration. By overriding
 //  customizeRegistration() , you can apply additional configuration to  DispatcherServlet .
 //  With the  ServletRegistration.Dynamic that’s given to  customizeRegistration() ,
 //  you can do several things, including set the load-on-startup priority by calling  set-
 //  LoadOnStartup() , set an initialization parameter by calling  setInitParameter() , and
 //  call  setMultipartConfig() to configure Servlet 3.0 multipart support.
   @Override
   protected void customizeRegistration(Dynamic registration) {
     registration.setMultipartConfig(
         new MultipartConfigElement("/tmp/spittr/uploads", 2097152, 4194304, 0));
   }

2.通过重定WebApplicationInitializer的onStartup来注册servlet

 package com.myapp.config;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration.Dynamic;
 import org.springframework.web.WebApplicationInitializer;
 import com.myapp.MyServlet;
 public class MyServletInitializer implements WebApplicationInitializer {
     @Override
     public void onStartup(ServletContext servletContext)
     throws ServletException {
         Dynamic myServlet =
             servletContext.addServlet("myServlet", MyServlet.class);
         myServlet.addMapping("/custom/**");
     }
 }

is a rather basic servlet-registering initializer class. It registers a servlet and maps it to a single path. You could use this approach to register DispatcherServlet manually. (But there’s no need, because AbstractAnnotationConfigDispatcher-
ServletInitializer does a fine job without as much code.)

3.通过重定WebApplicationInitializer的onStartup来注册filter

 @Override
 public void onStartup(ServletContext servletContext)
 throws ServletException {
     javax.servlet.FilterRegistration.Dynamic filter = servletContext.addFilter("myFilter", MyFilter.class);
     filter.addMappingForUrlPatterns(null, false, "/custom/*");
 }

4.To register one or more filters and map them to DispatcherServlet , all you need to do is override the getServletFilters() method of AbstractAnnotationConfigDispatcherServletInitializer .

 @Override
 protected Filter[] getServletFilters() {
     return new Filter[] { new MyFilter() };
 }

As you can see, this method returns an array of javax.servlet.Filter . Here it only returns a single filter, but it could return as many filters as you need. There’s no need to declare the mapping for the filters; any filter returned from getServletFilters() will automatically be mapped to DispatcherServlet