SpringBoot中的拦截器

Filter

典型场景 全局鉴权/接口耗时统计

@WebFilter("/*") 
public class CostFilter implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) {
        long start = System.currentTimeMillis();
        chain.doFilter(req, res); // 放行江湖令箭
        System.out.println("接口耗时："+(System.currentTimeMillis()-start)+"ms");
    }
}

HandlerInterceptor

典型场景 接口权限验证/请求参数自动装填

public class AuthInterceptor implements HandlerInterceptor {
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {
        String token = request.getHeader("X-Token");
        if(!"vip666".equals(token)){
            response.setStatus(403);
            return false; 
        }
        return true;
    }
}

@Configuration
publicclass WebMvcConfig implements WebMvcConfigurer {
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(new AuthInterceptor())
                .addPathPatterns("/api/**")
                .excludePathPatterns("/api/login");
    }
}

AOP拦截

典型场景 服务层方法缓存/事务管理

@Aspect
@Component
public class CacheAspect {
    @Around("@annotation(com.example.anno.Cacheable)")
    public Object aroundCache(ProceedingJoinPoint jp) {
        String cacheKey = buildKey(jp);
        Object cacheVal = redisTemplate.opsForValue().get(cacheKey);
        if(cacheVal != null) return cacheVal;
        
        Object result = jp.proceed();
        redisTemplate.opsForValue().set(cacheKey, result, 5, TimeUnit.MINUTES);
        return result;
    }
}

RestTemplate

典型场景 统一添加请求头/加密请求参数

public class TraceInterceptor implements ClientHttpRequestInterceptor {
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) {
        request.getHeaders().add("X-TraceId", UUID.randomUUID().toString());
        return execution.execute(request, body);
    }
}

// 注册水军
@Bean
public RestTemplate restTemplate() {
    RestTemplate rt = new RestTemplate();
    rt.getInterceptors().add(new TraceInterceptor());
    return rt;
}

Feign拦截器

典型场景 统一签名计算/Header透传

public class FeignAuthInterceptor implements RequestInterceptor {
    @Override
    public void apply(RequestTemplate template) {
        template.header("Authorization", "Bearer " + SecurityContext.getToken());
    }
}

@Configuration
public class FeignConfig {
    @Bean
    public FeignAuthInterceptor feignAuthInterceptor() {
        returnnew FeignAuthInterceptor();
    }
}

WebFilter

典型场景 响应式编程统一编码/跨域处理

@Component
public class CorsWebFilter implements WebFilter {
    @Override
    public Mono<Void> filter(ServerWebExchange exchange, WebFilterChain chain) {
        ServerHttpResponse response = exchange.getResponse();
        response.getHeaders().add("Access-Control-Allow-Origin", "*");
        return chain.filter(exchange);
    }
}

总结

顺序

Filter -> Interceptor -> AOP ，越早拦截越省力（但别在Filter里做业务）

性能

用Arthas监控拦截链路耗时

# 查看HandlerInterceptor耗时
trace *.preHandle '#cost>10'
 
# 诊断AOP切面
watch com.example.aop.*Aspect * '{params,returnObj}' -x 3