Springboot--web application development-servlets, Filters, listeners

I. Web development using a Controller can basically accomplish most of the requirements, but we may also use Servlets, Filter, listener, and so on.

Two. Three ways to implement in spring boot

Method one: Gain control by registering Servletregistrationbean, Filterregistrationbean, and Servletlistenerregistrationbean

Servlet class:

package Com.demo.example.util.servlet;import Java.io.IOException;import Javax.servlet.servletexception;import Javax.servlet.http.httpservlet;import Javax.servlet.http.httpservletresponse;import Javax.servlet.http.httpservletrequest;public class CustomServlet Extends HttpServlet {/** * */private static final long serialversionuid = 1L; @Overrideprotected void Doget (httpservletreq Uest request, HttpServletResponse response) throws Servletexception, IOException {//TODO auto-generated method StubSystem.out.println ("servlet Get Method");d Opost (request, response);} @Overrideprotected void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException {//TODO auto-generated method StubSystem.out.println ("Servlet get Method"); Response.getwriter (). Write (" Hello world ");}} 
 
 Filter Class: 

Package Com.demo.example.util.filter;import Java.io.ioexception;import Javax.servlet.filter;import Javax.servlet.filterchain;import Javax.servlet.filterconfig;import Javax.servlet.servletexception;import Javax.servlet.servletrequest;import Javax.servlet.servletresponse;public class Custonfilter implements Filter {@ Overridepublic void Destroy () {//TODO auto-generated method StubSystem.out.println ("Do Destroy");} @Overridepublic void DoFilter (ServletRequest request, servletresponse response, Filterchain chain) throws IOException, servletexception {System.out.println ("do Filter"); Chain.dofilter (request, response);} @Overridepublic void init (Filterconfig arg0) throws Servletexception {//TODO auto-generated method StubSystem.out.println ("do init");}}

Listener class:

Package Com.demo.example.util.listener;import Javax.servlet.servletcontextevent;import Javax.servlet.servletcontextlistener;public class Customlistener implements Servletcontextlistener {@Overridepublic void contextdestroyed (Servletcontextevent servletcontextevent) {//TODO auto-generated method StubSystem.out.println ( "Servletcontextevent");} @Overridepublic void contextinitialized (Servletcontextevent servletcontextevent) {//TODO auto-generated method StubSystem.out.println ("Servletcontextevent");}}

　

Registering beans (First way)

Code registration: (in the Springbootdemofilerservletlisapplication Class)

@Beanpublic servletregistrationbean<customservlet> Servletregistrationbean () {return new Servletregistrationbean<customservlet> (New Customservlet (), "/customservlet");} @Beanpublic filterregistrationbean<custonfilter> Filterregistrationbean () {return new Filterregistrationbean <CustonFilter> (New Custonfilter (), Servletregistrationbean ());} @Beanpublic servletlistenerregistrationbean<customlistener> Servletlistenerregistrationbean () {return new Servletlistenerregistrationbean<customlistener> (New Customlistener ());}

Registration of the second code: (similar to one)

@SpringBootApplicationpublic class Springbootdemofilerservletlisapplication implements Servletcontainerinitializer {@Overridepublic void Onstartup (set<class<?>> arg0, ServletContext ServletContext) throws servletexception {//TODO auto-generated method Stubservletcontext.addservlet ("Customservlet", New Customservlet ()). Addmapping ("/customservlet"); Servletcontext.addfilter ("Custonfilter", New Custonfilter ()). Addmappingforservletnames (Enumset.of (Dispatchertype.request), True, "Customservlet"); Servletcontext.addlistener ( New Customlistener ());}

The third type is based on comments:

First: Add in the Springbootdemofilerservletlisapplication class

In listener

In the servlet

On filter ("/*" for filtering global)

Springboot--web application development-servlets, Filters, listeners