spring boot——请求与参数校验——重要概念——配置Servlet、Filter、Listener——代码配置以及注解配置——华章...

秒速五厘米 2023-09-29 00:29 3阅读 0赞

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代码配置：

package org.example.webFilter.config;
    
    import org.example.webFilter.filter.FirstFilter;
    import org.example.webFilter.listener.FirstListener;
    import org.example.webFilter.servlet.FirstServlet;
    import org.springframework.boot.web.servlet.FilterRegistrationBean;
    import org.springframework.boot.web.servlet.ServletListenerRegistrationBean;
    import org.springframework.boot.web.servlet.ServletRegistrationBean;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    
    import javax.servlet.ServletContextListener;
    import java.util.ArrayList;
    import java.util.EventListener;
    import java.util.List;
    
    @Configuration
    public class WebConfig {
    
        /**
         * servletRegistrationBean:(使用代码注册Servlet(不需要@ServletComponentScan注解)).
         */
        @Bean
        public ServletRegistrationBean getFirstServlet()
        {
    
            ServletRegistrationBean registrationBean = new ServletRegistrationBean();
    
            registrationBean.setServlet(new FirstServlet());
    
            List<String> urlMappings = new ArrayList<String>();
    
            // 访问，可以添加多个
            urlMappings.add("/first");
            registrationBean.setUrlMappings(urlMappings);
    
            // 设置加载顺序
            registrationBean.setLoadOnStartup(1);
    
            return registrationBean;
        }
    
        /**
         * 注册拦截器
         */
        @Bean
        public FilterRegistrationBean getFirstFilter()
        {
    
            FirstFilter demoFilter = new FirstFilter();
    
            FilterRegistrationBean registrationBean=new FilterRegistrationBean();
    
            registrationBean.setFilter(demoFilter);
    
            List<String> urlPatterns=new ArrayList<String>();
    
            //拦截路径，可以添加多个
            urlPatterns.add("/*");
    
            registrationBean.setUrlPatterns(urlPatterns);
    
            //设置注册顺序
            registrationBean.setOrder(1);
    
            return registrationBean;
        }
    
        /**
         * 注册监听器
         */
        @Bean
        public ServletListenerRegistrationBean<ServletContextListener> getFirstListener()
        {
    
            ServletListenerRegistrationBean<ServletContextListener> registrationBean = new ServletListenerRegistrationBean<>();
    
            registrationBean.setListener(new FirstListener());
    
            // 设置注册顺序
            registrationBean.setOrder(1);
    
            return registrationBean;
        }
    
    }

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代码里面设置：

package org.example.webFilter.servlet;
    
    import javax.servlet.ServletConfig;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.io.PrintWriter;
    
    public class FirstServlet extends HttpServlet {
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("FirstServlet正在执行doGet");
            doPost(req, resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("FirstServlet正在执行doPost");
            //获取响应输出流PrinterWriter对象
            PrintWriter out = resp.getWriter();
            //使用输出流对象向客户端发送信息
            out.println("I'm a FirstServlet");//I'm a FirstServlet 会在客户端显示
        }
    
        @Override
        public void init(ServletConfig config) throws ServletException {
            System.out.println("FirstServlet正在执行init");
            super.init(config);
        }
    }

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注解设置：

package org.example.webFilter.servlet;
    
    import javax.servlet.ServletConfig;
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import java.io.IOException;
    import java.io.PrintWriter;
    
    @WebServlet(urlPatterns = "/second")
    public class SecondServlet extends HttpServlet {
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("SecondServlet正在执行doGet");
            doPost(req,resp);
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            System.out.println("SecondServlet正在执行doPost");
            //获取响应输出流PrinterWriter对象
            PrintWriter out = resp.getWriter();
            //使用输出流对象向客户端发送信息
            out.println("I'm a SecondServlet");//I'm a SecondServlet 会在客户端显示
        }
    
        @Override
        public void init(ServletConfig config) throws ServletException {
            System.out.println("SecondServlet正在执行init");
            super.init(config);
        }
    
    }

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package org.example.webFilter.filter;
    
    import javax.servlet.*;
    import java.io.IOException;
    
    public class FirstFilter implements Filter {
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
            System.out.println("FirstFilter正在执行doFilter");
            chain.doFilter(request, response);//放行
        }
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("FirstFilter正在执行init");
        }
    
        @Override
        public void destroy() {
            System.out.println("FirstFilter正在执行destroy");
        }
    }

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package org.example.webFilter.filter;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.IOException;
    
    @WebFilter(filterName = "secondFilter", urlPatterns = "/*")
    public class SecondFilter implements Filter {
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
            System.out.println("SecondFilter正在执行doFilter");
            chain.doFilter(request, response);//放行
        }
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("SecondFilter正在执行init");
        }
    
        @Override
        public void destroy() {
            System.out.println("SecondFilter正在执行destroy");
        }
    }

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package org.example;
    
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.boot.web.servlet.ServletComponentScan;
    
    
    @SpringBootApplication
    @ServletComponentScan("org.example.webFilter")
    public class HelloWorldApplication
    {
    
        public static void main(String[] args)
        {
    
            SpringApplication.run(HelloWorldApplication.class, args);
    
        }
    }

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package org.example.webFilter.listener;
    
    import javax.servlet.ServletContextEvent;
    import javax.servlet.ServletContextListener;
    
    public class FirstListener implements ServletContextListener {
    
        @Override
        public void contextInitialized(ServletContextEvent sce) {
            System.out.println("FirstListener监听器正在初始化");
            System.out.println("servlet container："+sce.getServletContext().getServerInfo());
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) {
            System.out.println("FirstListener监听器正在 销毁");
        }
    }

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package org.example.webFilter.listener;
    
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    
    import javax.servlet.ServletContextEvent;
    import javax.servlet.ServletContextListener;
    import javax.servlet.annotation.WebListener;
    import javax.servlet.http.HttpSessionEvent;
    import javax.servlet.http.HttpSessionListener;
    
    @WebListener
    public class SecondListener implements ServletContextListener {
    
        @Override
        public void contextInitialized(ServletContextEvent sce) {
            System.out.println("SecondListener监听器正在初始化");
            System.out.println("servlet container："+sce.getServletContext().getServerInfo());
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) {
            System.out.println("SecondListener监听器正在 销毁");
        }
    }

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