05、Spring Boot - 中整合 Web 层技术-5800字匠心出品

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：