SpringBoot中实现拦截器和过滤器

1.过滤器和拦截器简述

过滤器Filter和拦截器Interceptor，在功能方面很类似，但在具体实现方面差距还是比较大。

1.1 运行顺序不同：Filter →Servlet →Interceptor→Controller；
1.2 配置方式不同：Filter在web.xml中进行配置，Interceptor在Spring的配置文件中进行配置（或注解）；
1.3 依赖环境不同：Filter依赖于Servlet容器，而Interceptor不依赖Servlet容器；
1.4 操作对象不同：Filter只能对request和response进行操作，而Interceptor可对request、response、handler、modelAndView、exception进行操作（对Spring MVC生态下组件的操作能力）。

2.过滤器的配置

2.1 自定义过滤器，实现Filter接口(Springboot3开始，jakarta.servlet.Filter)

import javax.servlet.*;
import java.io.IOException;public class MyFilter implements Filter {}

2.2 重写doFilter，实现过滤逻辑，酌情放行

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.util.Objects;/*** 自定义过滤器：实现根据IP统计访问次数*/
public class MyFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {// 获取访问的IPHttpServletRequest request = (HttpServletRequest) servletRequest;String ip = request.getRemoteAddr();// 统计访问次数并输出HttpSession session = request.getSession();Integer count = (Integer) session.getAttribute("count");count = Objects.isNull(count) ? 1 : ++count;System.out.println("ip:" + ip + "\tcount:" + count);session.setAttribute("count", count);// 放行filterChain.doFilter(servletRequest, servletResponse);}
}

2.3 添加@WebFilter和@ServletComponentScan注解，实现过滤的范围配置

import javax.servlet.annotation.WebFilter;/*** 自定义过滤器：实现根据IP统计访问次数*/
@WebFilter(urlPatterns = "/*")
public class MyFilter implements Filter {@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {// 放行filterChain.doFilter(servletRequest, servletResponse);}
}

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;@SpringBootApplication
@ServletComponentScan(basePackages = "com.neusoft.springboot.filter")
public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}
}

3.拦截器的配置

3.1 自定义拦截器，实现HandlerInterceptor接口

import org.springframework.web.servlet.HandlerInterceptor;public class MyInterceptor implements HandlerInterceptor {}

3.2 实现接口中的拦截方法（preHandle-请求执行前、postHandler-请求执行后、afterCompletion-视图渲染后）

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 {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {// 记录访问IP的次数逻辑// 获取访问的IPString ip = request.getRemoteAddr();// 统计访问次数并输出HttpSession session = request.getSession();Integer count = (Integer) session.getAttribute("count");count = Objects.isNull(count) ? 1 : ++count;System.out.println("ip:" + ip + "\tcount:" + count);session.setAttribute("count", count);// 放行return true;}
}

3.3 创建配置类，实现WebMvcConfigurer接口，重写addInterceptors方法

import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;public class InterceptorConfiguration implements WebMvcConfigurer {@Overridepublic void addInterceptors(InterceptorRegistry registry) {MyInterceptor myInterceptor = new MyInterceptor();registry.addInterceptor(myInterceptor).addPathPatterns("/*");}
}