Spring Boot (教程八： 过滤器、监听器、拦截器)

GitHub 地址：

https://github.com/asd821300801/Spring-Boot.git

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过滤器Filter

在src下创建com.example.filter包

• 创建 ServletFilter.java 实现 Filter 方法

package com.example.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;import javax.servlet.annotation.WebFilter;/** * Servlet Filter implementation class ServletFilter * 注解注册过滤器：实现 javax.servlet.Filter接口  * filterName 是过滤器的名字 * urlPatterns 是需要过滤的请求 ，这里只过滤servlet/* 下面的所有请求 */@WebFilter(filterName="ServletFilter",urlPatterns="/servlet/*")public class ServletFilter implements Filter {    /**     * Default constructor.      */    public ServletFilter() {        // TODO Auto-generated constructor stub    }    /**     * @see Filter#destroy()     */    public void destroy() {        System.out.println("过滤器被销毁。");    }    /**     * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)     */    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {        // TODO Auto-generated method stub        // place your code here        System.out.println("过滤器正在执行...");        // pass the request along the filter chain        chain.doFilter(request, response);    }    /**     * @see Filter#init(FilterConfig)     */    public void init(FilterConfig fConfig) throws ServletException {        System.out.println("初始化过滤器。");    }}

测试

http://localhost:8080/servlet/servlet2.action

控制台输出：

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监听器Listener

在src下创建com.example.listener包

• 创建 ContextListener.java 类

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package com.example.listener;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.annotation.WebListener;/** * Application Lifecycle Listener implementation class ContextListener * @author LingDu */@WebListenerpublic class ContextListener implements ServletContextListener {    /**     * Default constructor.      */    public ContextListener() {        // TODO Auto-generated constructor stub    }    /**     * @see ServletContextListener#contextDestroyed(ServletContextEvent)     */    public void contextDestroyed(ServletContextEvent arg0)  {          System.out.println("监听器被销毁");    }    /**     * @see ServletContextListener#contextInitialized(ServletContextEvent)     */    public void contextInitialized(ServletContextEvent arg0)  {          System.out.println("监听器初始化。");    }}

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项目启动的时候 监听器是先被初始化的

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拦截器Interceptor

创建拦截器

      在src下创建com.example.interceptor包，
创建MyInterceptor.java类，实现HandlerInterceptor接口，重写里面3个主要的方法。

• MyInterceptor.java

package com.example.interceptor;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.web.servlet.HandlerInterceptor;import org.springframework.web.servlet.ModelAndView;/** * 1、创建拦截器类并实现 HandlerInterceptor 接口 * @author LingDu */public class MyInterceptor implements HandlerInterceptor {    @Override    public void afterCompletion(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, Exception arg3)            throws Exception {        System.out.println("拦截器MyInterceptor------->3、请求结束之后被调用，主要用于清理工作。");    }    @Override    public void postHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2, ModelAndView arg3)            throws Exception {        System.out.println("拦截器MyInterceptor------->2、请求之后调用，在视图渲染之前，也就是Controller方法调用之后");    }    @Override    public boolean preHandle(HttpServletRequest arg0, HttpServletResponse arg1, Object arg2) throws Exception {        System.out.println("拦截器MyInterceptor------->1、请求之前调用，也就是Controller方法调用之前。");        return true;//返回true则继续向下执行，返回false则取消当前请求    }}

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注册拦截器

      在src下创建com.example.interceptor包
创建InterceptorConfigurerAdapter类，继承WebMvcConfigurerAdapter类，重写addInterceptors方法

• InterceptorConfigurerAdapter.java

注意：需要加上@Configuration注解

package com.example.interceptor;import org.springframework.context.annotation.Configuration;import org.springframework.web.servlet.config.annotation.InterceptorRegistry;import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;/** * 创建java类继承WebMvcConfigurerAdapter类，重写addInterceptors方法 * @author LingDu */@Configurationpublic class InterceptorConfigurerAdapter extends WebMvcConfigurerAdapter {    /**     * 该方法用于注册拦截器     * 可注册多个拦截器，多个拦截器组成一个拦截器链     */    @Override    public void addInterceptors(InterceptorRegistry registry) {        // addPathPatterns 添加路径        // excludePathPatterns 排除路径        registry.addInterceptor(new MyInterceptor()).addPathPatterns("/*.*");        super.addInterceptors(registry);    }}

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页面访问：

http://localhost:8080/page1.action

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成功拦截：

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工程目录图