spring-java面向切面拦截器

        切面，就是可以在代码执行的时候，在它执行的前面添加一个东西，一般我们用来做登陆拦截器验证以及敏感词的过滤。

        他就3个东西，指定切点（要执行的代码），before代码执行前面加东西。after代码后加东西。一般我们只用切点和before。

1.引入相关依赖

    org.springframework.boot
    spring-boot-starter-aop

2.passToken注解（可有可无）

主要是为了让加注解的接口可以访问，比如说登陆和注册

package xxxx

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 不需要做登录验证的加上当前注解
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface PassToken {
    boolean required() default true;
}

3.切面

这里需要写一个返回方法 sendJsonMessage，用于返回信息

package com.dengta.tanzhiwcustomermarket.config;


import com.alibaba.fastjson.JSONObject;
import com.dengta.tanzhiwcustomermarket.tools.RedisUtils;
import com.dengtacj.tanzhiw.common.api.ResultCode;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@Aspect
@Configuration
public class ControllerAspect {

    private final static Logger logger = LoggerFactory.getLogger(ControllerAspect.class);

    // 定义切点Pointcut  自行写入对应的controller包路径
    @Pointcut("execution(* com.dengta.tanzhiwcustomermarket.controller.*.*(..))")
    public void pointCut() {
    }

    @Before("execution(* com.dengta.tanzhiwcustomermarket.controller.*.*(..))&&!@annotation(com.dengta.tanzhiwcustomermarket.config.PassToken)")
    public void before(JoinPoint joinPoint) throws Throwable {
        //获取token
        ServletRequestAttributes requestAttributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = requestAttributes.getRequest();
        String accessToken = request.getHeader("authorization");
        HttpServletResponse response = requestAttributes.getResponse();
        if(accessToken==null){//没有token直接结束
            JSONObject jsonObject = new JSONObject();
            jsonObject.put("code",500);
            jsonObject.put("message","暂未登录或token已经过期");

            sendJsonMessage(response,jsonObject);//必须要有这个
            return;//放行
        }
    }

    public static void sendJsonMessage(HttpServletResponse response, Object obj) {
        try {
            response.setContentType("application/json; charset=utf-8");
            response.setStatus(200);
            ServletOutputStream outputStream = response.getOutputStream();
            outputStream.write(obj.toString().getBytes("UTF-8"));
            outputStream.close();
            response.flushBuffer();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

测试结果