由於SpringBoot是通過jar包的形式執行，其內部嵌入了Servlet容器，專案中不存在web.xml檔案，所以註冊三大元件就不能通過web.xml檔案註冊。

1.註冊servlet

建立servlet

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MyServlet extends HttpServlet {

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}

	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		resp.getWriter().write("自定義servlet");
	}

}
 

註冊servlet

import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.peng.demo.servlet.MyServlet;

@Configuration
public class MyServerConfig {
	
	//註冊servlet
	@Bean
	public ServletRegistrationBean<MyServlet> myServlet() {
		ServletRegistrationBean<MyServlet> servletRegistrationBean = new ServletRegistrationBean<MyServlet>(new MyServlet(),"/myServlet");//對映地址
		return servletRegistrationBean;
	}
	

}
 

2.註冊Filter

建立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 MyFilter implements Filter {

	//銷燬
	@Override
	public void destroy() {

	}

	//過濾
	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
			throws IOException, ServletException {
		System.out.println("filter執行啦!!!!!!!!!!");
		chain.doFilter(arg0, arg1);
	}

	//初始化
	@Override
	public void init(FilterConfig arg0) throws ServletException {

	}

}
 

註冊Filter

//註冊Filter
	@Bean
	public FilterRegistrationBean myFilter(){
		FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
		filterRegistrationBean.setFilter(new MyFilter());//指定攔截的filter
		filterRegistrationBean.setUrlPatterns(Arrays.asList("/hello","/myServlet"));//指定攔截路徑
		return filterRegistrationBean;
	}

3.註冊Listener

建立Listener

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;

public class MyListener implements ServletContextListener {

	@Override
	public void contextDestroyed(ServletContextEvent arg0) {
		System.out.println("web應用關閉啦!!!!!!!!!!!!!");
	}

	@Override
	public void contextInitialized(ServletContextEvent arg0) {
		System.out.println("web應用啟動啦!!!!!!!!!!!!!");
	}

}

註冊Listener

//註冊listener
	@Bean
	public ServletListenerRegistrationBean myListener() {
		ServletListenerRegistrationBean servletListenerRegistrationBean=new ServletListenerRegistrationBean(new MyListener());
		return servletListenerRegistrationBean;
		
	}

4.總結

SprongBoot註冊SpringMVC的DispatcherServlet就是通過這種方式註冊的

DispatcherServletRegistrationBean為ServletRegistrationBean的實現類，預設攔截地址通過this.serverProperties.getServlet().getPath()獲取，即攔截所有(包括靜態資源，不包括jsp)

所以可以通過server.path修改前端控制器預設攔截路徑。