SpringBoot 过滤器、拦截器、监听器对比及使用场景分析

package com.dingwen.lir.filter;

import lombok.extern.slf4j.Slf4j;

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

/**
 *  在请求到达之前对 request 进行修改
 *
 * @author dingwen
 * 2021.04.30 14:54
 */
@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(" ");
    }


}

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;

/**
 * 请求过滤器
 * OncePerRequestFilter:
 * OncePerRequestFilter，顾名思义，它能够确保在一次请求中只通过一次filter.
 * 大家常识上都认为，一次请求本来就只filter一次，为什么还要由此特别限定呢，往往我们的常识和实际的实现并不真的一样，经过一番资料的查阅，此方法是为了兼容不同的web container，
 * 也就是说并不是所有的container都入我们期望的只过滤一次，servlet版本不同，执行过程也不同，
 * 因此，为了兼容各种不同运行环境和版本，默认filter继承OncePerRequestFilter是一个比较稳妥的选择。
 *
 * @author dingwen
 * 2021.04.30 15:59
 */
@Slf4j
public class RequestFilter extends OncePerRequestFilter {


    @Override
    public void destroy() {
        super.<p>本文来源gao!%daima.com搞$代*!码9网(</p>destroy();
        log.info("RequestFilter destroy");
    }

    /*
            OncePerRequestFilter.doFilter方法中通过request.getAttribute判断当前过滤器是否已执行
            若未执行过，则调用doFilterInternal方法，交由其子类实现
        */
    @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());
        }
    }
}