SpringBoot 过滤器、拦截器、监听器对比及使用场景分析-编程学习网

一、关系图理解

在这里插入图片描述

二、区别

1.过滤器

过滤器是在web应用启动的时候初始化一次, 在web应用停止的时候销毁
可以对请求的URL进行过滤, 对敏感词过滤
挡在拦截器的外层
实现的是 javax.servlet.Filter 接口，是 Servlet 规范的一部分
在请求进入容器后，但在进入servlet之前进行预处理，请求结束是在servlet处理完以后
依赖Web容器
会多次执行

过滤器简介

过滤器的英文名称为 Filter, 是 Servlet 技术中最实用的技术。如同它的名字一样，过滤器是处于客户端和服务器资源文件之间的一道过滤网，帮助我们过滤掉一些不符合要求的请求，通常用作 Session 校验，判断用户权限，如果不符合设定条件，则会被拦截到特殊的地址或者基于特殊的响应。

过滤器的使用

首先需要实现 Filter接口然后重写它的三个方法
•init 方法：在容器中创建当前过滤器的时候自动调用
•destory 方法：在容器中销毁当前过滤器的时候自动调用
•doFilter 方法：过滤的具体操作

1.1HttpServletRequestWrapper

在请求到达之前对 request 进行修改


package com.dingwen.lir.filter;

import lombok.extern.slf4j.Slf4j;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.util.Arrays;


@Slf4j
public class RequestWrapper extends HttpServletRequestWrapper {
    public RequestWrapper(HttpServletRequest request) {
        super(request);
        log.info("RequestWrapper");
    }

    @Override
    public String getParameter(String name) {
        // 可以对请求参数进行过滤
        return super.getParameter(name);
    }

    @Override
    public String[] getParameterValues(String name) {
        // 对请求参数值进行过滤
//        String[] values =super.getRequest().getParameterValues(name);
//        return super.getParameterValues(name);
        return "t e s t".split(" ");
    }


}

1.2 OncePerRequestFilter

OncePerRequestFilter，顾名思义，它能够确保在一次请求中只通过一次filter


package com.dingwen.lir.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;


@Slf4j
public class RequestFilter extends OncePerRequestFilter {


    @Override
    public void destroy() {
        super.destroy();
        log.info("RequestFilter destroy");
    }

    
    @Override
    protected void doFilterInternal(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, FilterChain filterChain) throws ServletException, IOException {
        try {
            RequestWrapper requestWrapper = new RequestWrapper(httpServletRequest);
            filterChain.doFilter(requestWrapper, httpServletResponse);
            log.info("RequestFilter");
            log.info(Arrays.toString(requestWrapper.getParameterValues("name")));
        } catch (Exception exception) {
            httpServletResponse.setCharacterEncoding("utf-8");
            httpServletResponse.setContentType("application/json; charset=utf-8");
            PrintWriter writer = httpServletResponse.getWriter();
            writer.write(exception.toString());
        }
    }
}

1.3 配置


package com.dingwen.lir.configuration;

import com.dingwen.lir.filter.RequestFilter;
import com.dingwen.lir.filter.RequestWrapper;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import javax.servlet.Filter;


@Configuration
public class FilterConfig {

    @Bean
    public RequestFilter requestFilter(){
        return new RequestFilter();
    }
    @Bean
    public FilterRegistrationBean<RequestFilter> registrationBean() {
        FilterRegistrationBean<RequestFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(requestFilter());
        registrationBean.addUrlPatterns("/filter
@Component
public class PageInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        User user = (User)request.getSession().getAttribute("user");
        if (!ObjectUtils.isEmpty(user)) {
            return true;
        } else {
            // 不管是转发还是重定向，必须返回false。否则出现多次提交响应的错误
            redirect(request, response);
            return false;
        }
    }

    
    public void redirect(HttpServletRequest request, HttpServletResponse response) throws IOException {

        if("XMLHttpRequest".equals(request.getHeader("X-Requested-With"))){// ajax
            //获取当前请求的路径
            response.setHeader("Access-Control-Expose-Headers", "REDIRECT,CONTENT_PATH");
            //告诉ajax我是重定向
            response.setHeader("REDIRECT", "REDIRECT");
            //告诉ajax我重定向的路径
            StringBuffer url = request.getRequestURL();
            String contextPath = request.getContextPath();
            response.setHeader("CONTENT_PATH", url.replace(url.indexOf(contextPath) + contextPath.length(), url.length(), "/").toString());
        }else{// http
            response.sendRedirect( "/page/login");
        }

        response.getWriter().write(403);
        response.setStatus(HttpServletResponse.SC_FORBIDDEN);
    }
}

2.2配置


package com.dingwen.lir.configuration;

import com.dingwen.lir.interceptor.PageInterceptor;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


@Configuration
public class MyWebMvcConfigurer implements WebMvcConfigurer {

    
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        // 拦截器默认的执行顺序，就是它的注册顺序，也可以通过Order手动设置控制，值越小越先执行。
//        registry.addInterceptor(new PageInterceptor()).addPathPatterns("
    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/page/ajax").setViewName("ajax");
    }


    
//    @Override
//    public void addResourceHandlers(ResourceHandlerRegistry registry) {
        registry.addResourceHandler("/static
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new PageInterceptor()).addPathPatterns("/**")
                .excludePathPatterns("/page/login", "/user/login","/page/ajax","/static/**");
    }

SpringBoot2.x 自定义静态资源映射


spring:
  mvc:
    static-path-pattern: /static/**

默认目录
classpath:/META-INF/resources
classpath:/resources
classpath:/static
classpath:/public
优先级：META-INF/resources > resources > static > public

2.登录拦截ajax重定向

由于ajax是异步的，还在当前页面进行的局部请求。当拦截到登录请求时，即使重定向也无法生效。需采用服务端给地址由前端进行跳转。详细见登录拦截器代码。


// 前端处理
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>AJAX</title>
    <script src="https://code.jquery.com/jquery-3.0.0.min.js"></script>
</head>
<body>
    <button>USER</button>
</body>
</html>

<script>
    $.ajaxSetup({
        complete:function(xhr,status){
            //拦截器实现超时跳转到登录页面
            let win = window;
            // 通过xhr取得响应头
            let REDIRECT = xhr.getResponseHeader("REDIRECT");
            //如果响应头中包含 REDIRECT 则说明是拦截器返回的需要重定向的请求
            if (REDIRECT === "REDIRECT")
            {
                while (win !== win.top)
                {
                    win = win.top;
                }
                win.location.href = xhr.getResponseHeader("CONTEXTPATH");
            }
        }
    });
    $("button").click(function(){
        $.get("/page/user", function(result){
            $("div").html(result);
        });
    });
</script>