Spring Boot 学习笔记《添加：Filter、Listener、Interceptor》

我不是女神ヾ 2022-11-30 01:38 221阅读 0赞

### SpringBoot 2.x 添加：过滤器 Filter、拦截器 Interceptor、监听器 Listener ###

*  Filter、Interceptor 区别
 *  Filter、Interceptor 的先后顺序
 *  过滤器 Filter
 *   *  过滤器的顺序
     *  创建过滤器类
     *  配置类注册过滤器
 *  拦截器 Interceptor
 *   *  过滤器的顺序
     *  创建拦截器类
     *  配置类注册拦截器
 *  监听器 Listener
 *   *  用途
     *  Servlet 作用域范围
     *  监听器(接口)种类
     *  监听器类 \`MyListener.class\`
 *  参考资料
 *   *  Annotation
     *  Filter
     *  Interceptor
     *  Listener

# Filter、Interceptor 区别 #

<table> 
 <thead> 
  <tr> 
   <th>-</th> 
   <th>Filter</th> 
   <th>Interceptor</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>规范不同</td> 
   <td>在<code>Servlet规范</code>中定义</td> 
   <td>由<code>Spring容器</code>支持</td> 
  </tr> 
  <tr> 
   <td>使用范围</td> 
   <td>只能用于<code>Web应用</code></td> 
   <td>可以用于<code>任何Java应用</code></td> 
  </tr> 
  <tr> 
   <td>可使用的思源不同</td> 
   <td>无法使用<code>Spring</code>资源</td> 
   <td>可使用<code>Spring</code>资源</td> 
  </tr> 
  <tr> 
   <td>控制颗粒度不同</td> 
   <td>在<code>Servlet前后</code></td> 
   <td>在<code>方法前后</code></td> 
  </tr> 
 </tbody> 
</table>

1.  过滤器颗粒度比较大，在拦截器之外，一般用于系统级别的针对所有请求的统一处理的场景 。

# Filter、Interceptor 的先后顺序 #

Filter（ DispactherServlet（ Interceptor（ Controller() ）））

# 过滤器 Filter #

1.  创建过滤器类。
2.  注册过滤器。（有3种方式。xml方式忽略。只讨论下面两种）  
    2.1. 在过滤器类上添加`@WebFilter`  
    2.2. 添加配置类。

## 过滤器的顺序 ##

**Tomcat【 A-Filter > B-Filter > C-Filter > DispactherServlet > C-Filter > B-Filter > A-Filter】**

## 创建过滤器类 ##

这里直接使用了`@WebFilter`注解的方式。这种方式添加的`过滤器顺序`是按`过滤器名`的`字母顺序`排的。

package com.example.demo.filter;
    
    
    import javax.servlet.*;
    import java.io.IOException;
    
    @WebFilter(filterName = "myFilter", urlPatterns = { "/*"})
    public class MyFilter implements Filter { 
        @Override
        public void init(FilterConfig filterConfig) throws ServletException { 
            System.out.println("--------------- 初始化 ----------------");
        }
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { 
            System.out.println("--------------- 请求处理前 ----------------");
            chain.doFilter(request, response);
            System.out.println("--------------- 请求处理后 ----------------");
        }
    
        @Override
        public void destroy() { 
            System.out.println("--------------- 销毁 ---------------");
        }
    }

## 配置类注册过滤器 ##

`setOrder`数值小的`先`

package com.example.demo.config;
    
    import com.example.demo.filter.MyFilter;
    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 filterRegistr(){ 
            FilterRegistrationBean registration = new FilterRegistrationBean();
            registration.setFilter( new MyFilter());
            registration.setName("myFilter");
            registration.addUrlPatterns("/*");
            registration.setOrder(666);
            return registration;
        }
    }

# 拦截器 Interceptor #

## 过滤器的顺序 ##

DispactherServlet`-->`  
拦截器【 preHandle()`->`单元方法`->`postHandle()`->`jsp资源`->`afterCompletion() 】  
`-->`DispactherServlet

## 创建拦截器类 ##

实现`HandlerInterceptor`接口定义拦截器。

package com.example.springbootdemo.interceptor;
    // import 略
    @Component
    public class MyInterceptor implements HandlerInterceptor { 
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws java.lang.Exception { 
            System.out.println("----------- 方法前 -----------");
            return true;
        }
    
        public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @org.springframework.lang.Nullable ModelAndView modelAndView) throws java.lang.Exception { 
            System.out.println("----------- 方法后，视图前 -----------");
        }
    
        public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @org.springframework.lang.Nullable java.lang.Exception ex) throws java.lang.Exception { 
            System.out.println("----------- 视图后，返回前 -----------");
        }
    }

## 配置类注册拦截器 ##

1.  拦截器按`注册的顺序`执行

package com.example.springbootdemo.config;
    // import 略
    @Configuration
    public class InterceptorConfig implements WebMvcConfigurer { 
        @Autowired
        private MyInterceptor myInterceptor;
    
        /** * 注册拦截器：写好的拦截器需要在这里添加注册才能生效 */
        @Override
        public void addInterceptors(InterceptorRegistry registry) { 
            registry.addInterceptor(myInterceptor)
                    .addPathPatterns("/**"); //拦截所有URL
        }
    }

# 监听器 Listener #

1.  创建监听器类 `XXXListener`，添加 `@WebListener` 注解。按需求实现监听器(接口)
2.  启动类添加`@ServletComponentScan`注解

## 用途 ##

`监听器` 用来监听特定的`Servlet`特定的生命周期，比如：初始化、销毁、属性添加删除

## Servlet 作用域范围 ##

`应用 Context` > `回话 Session` > `请求 Request`

## 监听器(接口)种类 ##

1.  [Interface ServletContextListener][]：初始化、销毁
2.  [Interface ServletContextAttributeListener][]：添加属性、移除属性、替换属性
3.  [Interface HttpSessionListener][]
4.  [Interface HttpSessionAttributeListener][]
5.  [Interface HttpSessionIdListener][]
6.  [Interface ServletRequestListener][]
7.  [Interface ServletRequestAttributeListener][]

## 监听器类 `MyListener.class` ##

实现两个意思一下，其它看自己需要。

package com.example.demo.listener;
    
    import javax.servlet.*;
    import javax.servlet.annotation.WebListener;
    import javax.servlet.http.HttpSessionAttributeListener;
    import javax.servlet.http.HttpSessionListener;
    
    @WebListener
    public class MyListener implements ServletContextListener, ServletContextAttributeListener, HttpSessionListener, HttpSessionAttributeListener, ServletRequestListener, ServletRequestAttributeListener
    { 
        @Override
        public void contextInitialized(ServletContextEvent sce) { 
            System.out.println("--------------- 初始化 ----------------");
        }
    
        @Override
        public void contextDestroyed(ServletContextEvent sce) { 
            System.out.println("--------------- 销毁 ---------------");
        }
    }

# 参考资料 #

[字母哥课堂：20年全新-Spring Boot 2.x从青铜到王者之钻石篇、filter、interceptor、listener、架构师、SpringBoot][20_-Spring Boot 2.x_filter_interceptor_listener_SpringBoot]  
[豆豆DE思念：过滤器，拦截器，监听器的区别][DE]  
[Servlet、Filter、Listener 注册方式演变][Servlet_Filter_Listener]

## Annotation ##

[@Configuration][Configuration]  
[@WebFilter][WebFilter]  
[@WebListener][WebListener]

## Filter ##

[Interface Filter][]  
[Class FilterRegistrationBean][]

## Interceptor ##

[Interface HandlerInterceptor ][Interface HandlerInterceptor]  
[Interface WebMvcConfigurer ][Interface WebMvcConfigurer]  
[Class InterceptorRegistry][]  
[Class InterceptorRegistration][]  
[SpringBoot 拦截器 Interceptor][SpringBoot _ Interceptor]  
[Spring MVC 学习笔记 7《拦截器（Interceptor）》][Spring MVC _ 7_Interceptor]  
[SpringBoot 静态资源访问配置][SpringBoot]  
[SpringBoot 设置跨域支持][SpringBoot 1]

## Listener ##

1.  [Interface ServletContextListener][]
2.  [Interface ServletContextAttributeListener][]
3.  [Interface HttpSessionListener][]
4.  [Interface HttpSessionAttributeListener][]
5.  [Interface HttpSessionIdListener][]
6.  [Interface ServletRequestListener][]
7.  [Interface ServletRequestAttributeListener][]

[Interface ServletContextListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/ServletContextListener.html
[Interface ServletContextAttributeListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/ServletContextAttributeListener.html
[Interface HttpSessionListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/http/HttpSessionListener.html
[Interface HttpSessionAttributeListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/http/HttpSessionAttributeListener.html
[Interface HttpSessionIdListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/http/HttpSessionIdListener.html
[Interface ServletRequestListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/ServletRequestListener.html
[Interface ServletRequestAttributeListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/ServletRequestAttributeListener.html
[20_-Spring Boot 2.x_filter_interceptor_listener_SpringBoot]: https://www.bilibili.com/video/av371865945
[DE]: https://www.cnblogs.com/lukelook/p/11079113.html
[Servlet_Filter_Listener]: https://blog.csdn.net/jx520/article/details/92638166
[Configuration]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/annotation/Configuration.html
[WebFilter]: https://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/annotation/WebFilter.html
[WebListener]: http://tomcat.apache.org/tomcat-9.0-doc/servletapi/javax/servlet/annotation/WebListener.html
[Interface Filter]: http://www.servlets.com/javadoc/javax/servlet/Filter.html
[Class FilterRegistrationBean]: https://docs.spring.io/spring-boot/docs/current/api/org/springframework/boot/web/servlet/FilterRegistrationBean.html
[Interface HandlerInterceptor]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/servlet/HandlerInterceptor.html
[Interface WebMvcConfigurer]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/servlet/config/annotation/WebMvcConfigurer.html
[Class InterceptorRegistry]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/servlet/config/annotation/InterceptorRegistry.html
[Class InterceptorRegistration]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/servlet/config/annotation/InterceptorRegistration.html
[SpringBoot _ Interceptor]: https://blog.csdn.net/jx520/article/details/103447115
[Spring MVC _ 7_Interceptor]: https://blog.csdn.net/jx520/article/details/89892090
[SpringBoot]: https://blog.csdn.net/jx520/article/details/103273953
[SpringBoot 1]: https://blog.csdn.net/jx520/article/details/103291541