springboot中的请求过滤filter与拦截interceptor分析

首先我们要定义一个类，实现标准的过滤器

java 复制代码

import lombok.extern.slf4j.Slf4j;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;


@WebFilter("/*")
@Slf4j
public class AuthFilter implements Filter {

    @Override //初始化方法，只会被执行一次
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
        log.info("AuthFilter初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("AuthFilter执行了");
        filterChain.doFilter(servletRequest, servletResponse); // 这里就是放行
    }

    @Override //销毁方法，只会被执行一次
    public void destroy() {
        Filter.super.destroy();
        log.info("AuthFilter销毁");
    }
}

由于filter是javaweb里面的类，不是spring里面自带的，所以我们还要在启动类上面加上注解

java 复制代码

@ServletComponentScan // 扫描Servlet,javaweb里面的类
@SpringBootApplication
public class TliasWebManagementApplication {

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

}

只拦截登录接口

java 复制代码

@WebFilter("/login")
@Slf4j
public class AuthFilter implements Filter {

    @Override //初始化方法，只会被执行一次
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
        log.info("AuthFilter初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        log.info("AuthFilter执行了");
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override //销毁方法，只会被执行一次
    public void destroy() {
        Filter.super.destroy();
        log.info("AuthFilter销毁");
    }
}

代码实现

xml 复制代码

 <dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.76</version>
 </dependency>

java 复制代码

package com.itheima.filter;
import com.alibaba.fastjson.JSONObject;
import com.itheima.pojo.Result;
import com.itheima.utils.JwtUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;


@WebFilter("/*")
@Slf4j
public class AuthFilter implements Filter {

    @Override //初始化方法，只会被执行一次
    public void init(FilterConfig filterConfig) throws ServletException {
        Filter.super.init(filterConfig);
        log.info("AuthFilter初始化");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        //获取请求的url
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String url = request.getRequestURL().toString();
        log.info("url:{}", url);
        //是否包含login,如果包含，则放行
        if (url.contains("login")) {
            log.info("登录操作，放行");
            filterChain.doFilter(servletRequest, servletResponse);
            return;
        }
        // 获取请求的token
        String token = request.getHeader("token");
        if (!StringUtils.hasLength(token)) {
            response.setStatus(401);
            log.info("token为空，请登录");
            Result error = Result.error("token not login");
            //在过滤器中，手动将结果输出到前端
            String notLogin = JSONObject.toJSONString(error);
            response.getWriter().write(notLogin);
            return;
        }
        // 解析token
        try {
            JwtUtils.parseJWT(token);
        } catch (Exception e) {
            e.printStackTrace();
            log.info("token解析失败");
            Result error = Result.error("not token");
            //在过滤器中，手动将结果输出到前端
            String notLogin = JSONObject.toJSONString(error);
            response.getWriter().write(notLogin);
            return;

        }
        // 放行
        filterChain.doFilter(servletRequest, servletResponse);
    }

    @Override //销毁方法，只会被执行一次
    public void destroy() {
        Filter.super.destroy();
        log.info("AuthFilter销毁");
    }
}

测试效果,没有登录，其他请求的返回