【Spring】过滤器、拦截器、监听器各自的实现方式

你的名字 2023-03-01 09:10 28阅读 0赞

**目录**

一、过滤器实现

1.1 SpringMVC 示例代码

1.2 SpringBoot 示例代码

1.3 调用顺序

二、拦截器实现

2.1 SpringMVC 实现拦截器

2.2 SpringBoot 实现拦截器

三、使用 WebMvcConfigurer 统一注册

--------------------

# 一、过滤器实现 #

## 1.1 SpringMVC 示例代码 ##

**过滤器一： DemoFilter.java**

public class DemoFilter implements Filter {
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("DemoFitler 初始化！");
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            System.out.println("DemoFitler 过滤！");
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        @Override
        public void destroy() {
            System.out.println("DemoFitler 销毁！");
        }
    }

**过滤器二：SecondFilter.java**

public class SecondFilter implements Filter {
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("SecondFilter 初始化！");
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            System.out.println("SecondFilter 过滤！");
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        @Override
        public void destroy() {
            System.out.println("SecondFilter 销毁！");
        }
    }

**配置 web.xml**

<!DOCTYPE web-app PUBLIC
            "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
            "http://java.sun.com/dtd/web-app_2_3.dtd" >
    <web-app>
        <display-name>Archetype Created Web Application</display-name>
    
        <servlet>
            <servlet-name>dispatcherServlet</servlet-name>
            <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
            
            <init-param>
                <param-name>contextConfigLocation</param-name>
                <param-value>classpath:springmvc.xml</param-value>
            </init-param>
        </servlet>
        <servlet-mapping>
            <servlet-name>dispatcherServlet</servlet-name>
            <url-pattern>/</url-pattern>
        </servlet-mapping>
    
    
        
        <listener>
            <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
        </listener>
        <context-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>classpath:applicationContext.xml</param-value>
        </context-param>
    
        
        <filter>
            <filter-name>demoFilter</filter-name>
            <filter-class>xyz.tom.filter.DemoFilter</filter-class>
            <init-param>
                <param-name>name</param-name>
                <param-value>contextFilter123</param-value>
            </init-param>
        </filter>
        <filter-mapping>
            <filter-name>demoFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
    
        
        <filter>
            <filter-name>secondFilter</filter-name>
            <filter-class>xyz.tom.filter.SecondFilter</filter-class>
            <init-param>
                <param-name>name</param-name>
                <param-value>contextFilter123</param-value>
            </init-param>
        </filter>
        <filter-mapping>
            <filter-name>secondFilter</filter-name>
            <url-pattern>/*</url-pattern>
        </filter-mapping>
    </web-app>

## 1.2 SpringBoot 示例代码 ##

需要引入依赖：

<dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>

package com.tom.springboot_trans.fitler;
    
    import org.springframework.stereotype.Component;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebFilter;
    import java.io.IOException;
    
    @Component
    @WebFilter(urlPatterns = "/*", filterName = "demoFilter")
    public class DemoFilter implements Filter {
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
            System.out.println("DemoFitler 初始化！");
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
            System.out.println("DemoFitler 过滤！");
            filterChain.doFilter(servletRequest, servletResponse);
        }
    
        @Override
        public void destroy() {
            System.out.println("DemoFitler 销毁！");
        }
    }

## 1.3 调用顺序 ##

**初始化顺序：** xml 文件越后面的过滤器，越先初始化

![20200723113332252.png][]

**过滤顺序：**xml 文件越前面的越先被调用

![20200723113351526.png][]

**销毁顺序：**xml 文件越后面的过滤器，越先被销毁

![20200723113404683.png][]

# 二、拦截器实现 #

## 2.1 SpringMVC 实现拦截器 ##

**编写拦截器**

package xyz.tom.interceptor;
    
    import org.springframework.web.servlet.HandlerInterceptor;
    import org.springframework.web.servlet.ModelAndView;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class DemoInterceptor implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            System.out.println("DemoInterceptor! 请求前拦截！");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            System.out.println("DemoInterceptor! 业务请求执行完毕！");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            System.out.println("DemoInterceptor! 处理完请求后被调用！");
        }
    }

**修改 SpringMVC.xml 的配置**

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:context="http://www.springframework.org/schema/context"
           xmlns:mvc="http://www.springframework.org/schema/mvc"
           xsi:schemaLocation="
            http://www.springframework.org/schema/beans
            https://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/mvc
            https://www.springframework.org/schema/mvc/spring-mvc.xsd
            http://www.springframework.org/schema/context
            https://www.springframework.org/schema/context/spring-context.xsd">
    
        
        <context:component-scan base-package="xyz.tom">
            <context:include-filter type="annotation" expression="org.springframework.stereotype.Controller"/>
        </context:component-scan>
    
        
        <bean id="internalResourceViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
            
            <property name="prefix" value="/WEB-INF/pages/"></property>
            
            <property name="suffix" value=".jsp"></property>
        </bean>
    
        
        <mvc:resources mapping="/js/**" location="/js/**"></mvc:resources>
        <mvc:resources mapping="/css/**" location="/css/**"></mvc:resources>
        <mvc:resources mapping="/images/**" location="/images/**"></mvc:resources>
    
        
        <mvc:annotation-driven></mvc:annotation-driven>
    
        
        <mvc:interceptors>
            <mvc:interceptor>
                <mvc:mapping path="/**"/>
                <bean class="xyz.tom.interceptor.DemoInterceptor"></bean>
            </mvc:interceptor>
        </mvc:interceptors>
    </beans>

## 2.2 SpringBoot 实现拦截器 ##

**引入依赖**

<dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>

**创建拦截器**

拦截器需要编写配置类，并使用 @Configuration注解来让编译器扫描它。多个拦截器时，拦截器执行顺序会根据注册顺序拦截。

**定义拦截器类**

public class DemoInterceptor implements HandlerInterceptor {
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
            System.out.println("DemoInterceptor! 请求前拦截！");
            return true;
        }
    
        @Override
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
            System.out.println("DemoInterceptor! 业务请求执行完毕！");
        }
    
        @Override
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
            System.out.println("DemoInterceptor! 处理完请求后被调用！");
        }
    }

**定义配置类**

# 三、使用 WebMvcConfigurer 统一注册 #

@Configuration
    public class WebMvcConfig implements WebMvcConfigurer {
    
        @Override
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(new DemoInterceptor()).addPathPatterns("/**");
            registry.addInterceptor(new SecondInterceptor()).addPathPatterns("/**");
            WebMvcConfigurer.super.addInterceptors(registry);
        }
    
        @Bean
        public FilterRegistrationBean demoFilterRegistration() {
            DemoFilter demoFilter = new DemoFilter();
            demoFilter.setUrlExclusion(Arrays.asList("/login"));
            FilterRegistrationBean registration = new FilterRegistrationBean(demoFilter);
            registration.addUrlPatterns("/*");
            return registration;
        }
    
    }

[20200723113332252.png]: /images/20230209/74cefdde138e4052bd3533334242106a.png
[20200723113351526.png]: /images/20230209/3c141c0f5e1f41b48834afbfe7c9590e.png
[20200723113404683.png]: https://img-blog.csdnimg.cn/20200723113404683.png