这节记录下如何使用aop或者使用interceptor实现用户请求的是否带token，本文只是简单检查用户请求是否带参数token，并不对token的正确性进行验证。通常要从后台缓存中进行token校验。

第一种方式：拦截器方式

第一步：新建一个拦截器package，名称为interceptor，新建一个拦截器。

java">@Component
public class TokenInterceptor implements HandlerInterceptor {
    Logger logger = LoggerFactory.getLogger(TokenInterceptor.class);

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        logger.info("preHandle执行中");
        String token  = request.getHeader("token");
        if(StringUtils.isBlank(token)){
            throw new BussinessException("无token，参数错误");
        }
        if(!token.equals("ceshi")){
            throw new BussinessException("token参数错误");
        };
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        logger.info("postHandle执行中");
        HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
    }


    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        logger.info("afterCompletion执行中");
        HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
    }
}

第二步：在WebMvcConfigurer配置类中注册拦截器

java">
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        WebMvcConfigurer.super.addInterceptors(registry);
        registry.addInterceptor(tokenInterceptor);//默认所有的url拦截
    }

第二种方式：使用AOP

编写一个aop类，添加上注解@Aspect和@Component。重写下面的方法

java">@Aspect
@Component
public class LoggerAspect {
    private static final Logger logger = LoggerFactory.getLogger(LoggerAspect.class);

    @Pointcut("execution(* cn.wcyf.wcai.controller.front.*.*(..))") // 定义切点
    public void pointcut() {}

    @Before("pointcut()")
    public void before() {
        logger.info("before方法中: ");
    }

    @After("pointcut()")
    public void after() {
        logger.info("after方法中: " );
    }

    @AfterReturning("pointcut()")
    public void afterReturn() {
        logger.info("AfterReturning方法中: " );
    }

    @AfterThrowing("pointcut()")
    public void threw() {
        logger.info("AfterThrowing方法中: " );
    }

    @Around("pointcut()")
    public Object around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        logger.info("Around方法开始: " + proceedingJoinPoint.getSignature());
        try {
            ServletRequestAttributes attrs  = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
            if(attrs!=null){
              HttpServletRequest request =  attrs.getRequest();
              String token = request.getHeader("token");
              if(StringUtils.isBlank(token)){
                  throw new BussinessException("参数错误，token为空");
              }
              if(!token.equals("ceshi")){
                  throw new BussinessException("token错误，这是aop测试");
              }
            }
            Object result = proceedingJoinPoint.proceed(); // 调用目标方法
            logger.info("Around方法结束: " + proceedingJoinPoint.getSignature() + ", 返回值: " + result);
            return result;
        } catch (Throwable ex) {
            logger.info("Around方法捕获异常: " + proceedingJoinPoint.getSignature() + ", 异常: " + ex.getMessage());
            throw ex; // 重新抛出异常，以便Spring可以正确处理
        }
    }
}

Object result = proceedingJoinPoint.proceed(); // 调用目标方法

这个代码可以执行调用目标方法，在这段代码前面可以实现前置通知，在这段代码后可以实现后置通知。