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