1.通过注解扫描完成 Servlet 组件的注册
创建 Servlet：
package com.dqcgm.springbootweb.servlet;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name = "First Servlet",urlPatterns = "/first")
public class FirstServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp){
System.out.println("First Servlet ............");
}
}
修改启动类：
package com.dqcgm.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//在 spring Boot 启动时会扫描@WebServlet 注解，并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
运行结果：
2.通过方法完成 Servlet 组件的注册
创建 Servlet：
package com.dqcgm.springbootweb.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SecondServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("SecondServlet............");
}
}
创建 Servlet 配置类：
package com.dqcgm.springbootweb.servlet;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ServletConfig {
@Bean
public ServletRegistrationBean getServletRegistrationBean() {
ServletRegistrationBean bean = new ServletRegistrationBean(new SecondServlet());
bean.addUrlMappings("/second");
return bean;
}
}
运行结果：
3.通过注解扫描完成 Filter 组件注册
创建 Filter：
package com.dqcgm.springbootweb.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter(filterName = "FirstFilter",urlPatterns = "/FirstFilter")
public class FirstFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
System.out.println("进入FirstFilter...........");
filterChain.doFilter(servletRequest,servletResponse);
System.out.println("离开FirstFilter............");
}
@Override
public void destroy() {
}
}
修改启动类：
package com.dqcgm.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//在 spring Boot 启动时会扫描@WebServlet 注解，并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
运行结果：
4.通过方法完成 Filter 组件注册
创建 Filter：
package com.dqcgm.springbootweb.filter;
import javax.servlet.*;
import java.io.IOException;
public class SecondFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
System.out.println("进入SecondFilter...........");
filterChain.doFilter(servletRequest,servletResponse);
System.out.println("离开SecondFilter............");
}
@Override
public void destroy() {
}
}
创建 Filter 配置类：
package com.dqcgm.springbootweb.filter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean getFilterRegistrationBean(){
FilterRegistrationBean bean = new FilterRegistrationBean(new SecondFilter());
bean.addUrlPatterns("/SecondFilter");
return bean;
}
}
5.通过注解扫描完成 Listener 组件注册
编写 Listener：
package com.dqcgm.springbootweb.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class FirstListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("Listener init ............");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}
修改启动类：
package com.dqcgm.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//在 spring Boot 启动时会扫描@WebServlet 注解，并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
运行结果：
6.通过方法完成 Listener 组件注册
编写 Listener：
package com.dqcgm.springbootweb.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
public class SecondListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent sce) {
System.out.println("SecondListener init ............");
}
@Override
public void contextDestroyed(ServletContextEvent sce) {
}
}
创建 Listener 配置类：
package com.dqcgm.springbootweb.listener;
import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class ListenerConfig {
@Bean
public ServletListenerRegistrationBean getServletListenerRegistrationBean(){
ServletListenerRegistrationBean bean = new ServletListenerRegistrationBean(new SecondListener());
return bean;
}
}
运行结果：
