在Spring Boot中整合Servlet、Filter、Listener的方式
写在前面
从零开始的Spring Boot(1、搭建一个Spring Boot项目Hello World)：https://www.cnblogs.com/gaolight/p/13097818.html
从零开始的Spring Boot(3、Spring Boot静态资源和文件上传)：https://www.cnblogs.com/gaolight/p/13130406.html
一、在Spring Boot中整合Servlet的方式
（一）整合Servlet方式一
1.如图创建Servlet包，FirstServlet类；
2. 修改FirstServlet内的代码，如下；
package com.demo.springbootweb.Servlet;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name="FirstServlet",urlPatterns = "/first")
public class FirstServlet extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("FirstServlet...");
}
}
3.为启动类xxxxApplication.java增加注解@ServletComponentScan
package com.demo.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//spring boot启动时扫描注解@WebServlet,并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
4.运行启动类main方法，在浏览器中输入地址：http://localhost:8080/first
可以看到控制台输出
（二）整合Servlet方式二
1.创建SecondServlet并修改代码如下：
package com.demo.springbootweb.Servlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServlet;
public class SecondServlet extends HttpServlet{
public void doGet(HttpServletRequest req, HttpServletResponse resp) {
System.out.println("SecondServlet...");
}
}
3. 创建config包和ServletConfig类，并修改代码；
该代码也可以写在启动类下，完成Servlet组件的注册
package com.demo.springbootweb.config;
import com.demo.springbootweb.Servlet.SecondServlet;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import javax.servlet.Servlet;
@Configuration
public class ServletConfig {
@Bean
public ServletRegistrationBean getServletRegistrationBean(){
ServletRegistrationBean bean=new ServletRegistrationBean((Servlet) new SecondServlet());
bean.addUrlMappings("/second");
return bean;
}
}
4. 运行启动类main方法，在浏览器输入：http://localhost:8080/second
可以看到控制台输出
二、在Spring Boot中整合Filter的方式
（一）整合Filter方式一
1. 在filter包下创建FirstFilter类，并修改代码；
package com.demo.springbootweb.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;
@WebFilter(filterName="FirstFilter",urlPatterns = "/first")
//@WebFilter(filterName="FirstFilter",urlPatterns = {"*.do","*.jsp"})
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() {
}
}
2. 之前在启动类中添加的@ServletComponentScan，同样可以扫描注解@WebFilter，
package com.demo.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//spring boot启动时扫描注解@WebServlet,@WebFilter,并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
3. 运行启动类main方法，在浏览器中输入http://localhost:8080/first，控制台输出
（二）整合Filter方式二
1.如图创建SecondFilter类，并修改代码；
package com.demo.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() {
}
}
2. 为启动类添加注解；
package com.demo.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//spring boot启动时扫描注解@WebServlet,@WebFilter,并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
3. 创建FilterConfig类，修改代码；
package com.demo.springbootweb.config;
import com.demo.springbootweb.filter.SecondFilter;
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(new String[]{"*.do","*.jsp"});
bean.addUrlPatterns("/second");
return bean;
}
}
4. 运行启动类main方法，在浏览器中输入：http://localhost:8080/second
三、在Spring Boot中整合Listener的方式
（一）整合Listener方式一
1.创建FirstListener类，并修改代码
package com.demo.springbootweb.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.annotation.WebListener;
@WebListener
public class FirstListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent event) {
}
@Override
public void contextInitialized(ServletContextEvent event) {
System.out.println("FirstListener....init...");
}
}
2. 为启动类添加注解
package com.demo.springbootweb;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;
@SpringBootApplication
@ServletComponentScan//spring boot启动时扫描注解@WebServlet,@WebFilter,@WebListener并将该类实例化
public class SpringbootwebApplication {
public static void main(String[] args) {
SpringApplication.run(SpringbootwebApplication.class, args);
}
}
3. 运行启动类main()方法，控制台输出
（二）整合Listener方式二
1.创建SecondListener类，修改代码：
package com.demo.springbootweb.listener;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class SecondListener implements ServletContextListener {
@Override
public void contextDestroyed(ServletContextEvent event) {
}
@Override
public void contextInitialized(ServletContextEvent event) {
System.out.println("SecondListener....init...");
}
}
2.创建ListenerConfig类，修改代码：
package com.demo.springbootweb.config;
import com.demo.springbootweb.listener.SecondListener;
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;
}
}
4. 运行启动类main()方法，控制台输出：
