Filter和Interceptor

Filter过滤器和拦截器Interceptor

1. 简介

过滤器和拦截器,在功方面很类似,但在具体实现方面差距还是很大；

过滤器出现的时间早于拦截器

2. 添加依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
</dependency>

3. 过滤器

需求: 统计每个ip访问某个controller的次数

3.1 编写逻辑

注意filter的包路径为 javax.servlet.*

package com.health.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.Objects;

@WebFilter(urlPatterns = "/*")   //表示拦截的范围
public class Myfilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //将接口转为实现类
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        //通过getRemoteAddr 获取客户端 IP 地址
        String ip = request.getRemoteAddr();
		//获取会话对象
        HttpSession session = request.getSession();
        //从 HttpSession 对象中获取指定名称的属性值。
        Integer count = (Integer) session.getAttribute("count");
        //如果count为null则默认1不为null则自增
        count = Objects.isNull(count)?1:++count;
        System.out.println("ip:"+ip+"\tcount:"+count);
        //将新的count值存入session中
        session.setAttribute("count", count);

        filterChain.doFilter(servletRequest, servletResponse);
    }
}

3.2 在启动类加上注解

@ServletComponentScan(basePackages = "org.example.filter")

package org.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan(basePackages = "org.example.filter")
public class TestApplication {

    public static void main(String[] args) {
        SpringApplication.run(TestApplication.class, args);
    }
}

3.拦截器

需求: 统计每个ip访问某个controller的次数

3.1 编写逻辑

package org.example;


import org.springframework.web.servlet.HandlerInterceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.util.Objects;

public class MyInterceptor implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        //通过getRemoteAddr 获取客户端 IP 地址
        String ip = request.getRemoteAddr();
        //获取会话对象
        HttpSession session = request.getSession();
        //从 HttpSession 对象中获取指定名称的属性值。
        Integer count = (Integer) session.getAttribute("count");
        //如果count为null则默认1不为null则自增
        count = Objects.isNull(count)?1:++count;
        System.out.println("ip:"+ip+"\tcount:"+count);
        //将新的count值存入session中
        session.setAttribute("count", count);

		//true表示放行
        return true;
    }
}

3.2 添加配置类

package org.example.config;

import org.example.MyInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

@Configuration
public class interceptorConfig implements WebMvcConfigurer {

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        MyInterceptor myInterceptor = new MyInterceptor();
        registry.addInterceptor(myInterceptor) //加入拦截器
                .addPathPatterns("/**") //加入拦截范围
                .excludePathPatterns("/user/login"); //不需要拦截的路径
    }
}

x.总结

1. Filter依赖于Servlet容器,属于Servlet规范的一部分,而Interceptor依赖于SpringMvC框架
2. Filter的生命周期由Servlet容器管理,而Interceptor通过IOC容器来管理,可通过注入等方式来获取其Bean的实例
3. Filter可拦截所有web资源(包括Jsp, Servlet,静态资源),而Interceptor则只拦截Controller.