Filter，Interceptor，AOP 区别与实例

	filter	interceptor	aspect
入参	ServletRequest, ServletResponse	HttpServletRequest , HttpServletResponse , Object handler	ProceedingJoinPoint
原理	依赖于servlet容器，与框架无关	Spring框架拦截器，基于Java反射机制	动态代理（jdk动态代理/cglib）
范围	RESTful api	RESTful api	Spring Bean

• 顺序：Filter -> Interceptor -> ControllerAdvie -> Aspect -> Controller -> Aspect -> ControllerAdvie -> Interceptor -> Filter
  *ps: ControllerAdvie 是controller的增强，和ExceptionHandler一起用来做全局异常。

Interceptor

• 用法

1. 继承HandlerInterceptorAdapter（是HandlerInterceptor接口的实现类，有默认的空实现，可以*选择自己需要的method去实现）

public class MyInterceptor extends HandlerInterceptorAdapter{
    @Override
    //如果preHandle返回false，这个url请求的controller方法不会进去（被拦截）
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        return false;
    }
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
    }
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
    }

2. • SpringBoot 项目:
     继承WebMvcConfigurerAdapter（是WebMvcConfigurer接口的实现类），加@Configuration注解，引入写好的Interceptor，调用addInterceptors方法。

@Configuration
public class WebConfigurer extends WebMvcConfigurerAdapter {
    @Autowired
    private MyInterceptor myInterceptor;
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(myInterceptor)
                .addPathPatterns("/url1/**", "/url2/**")
                .excludePathPatterns("/url1/exclude");
    }
    super.addInterceptors(registry);
}

• 非SpringBoot:

<mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/url/**" />
            <bean class="path.MyInterceptor" />
        </mvc:interceptor>
</mvc:interceptors>

AOP

• 用法
  @Aspect @Component @Pointcut @Around @Before...

@Component
@Aspect
public class MyAspect {
    @Pointcut("execution(public * com.citi..controller..*Controller.*(..) ) && @annotation(org.springframework.web.bind.annotation.RequestMapping)")
    public void pointcut() {
    }
    @Around("pointcut()")
    public Object function(ProceedingJoinPoint joinPoint) throws Throwable {
        // do something
        // 获取增强的类
        // 获取增强的方法名
        // 获取增强方法的参数
        return joinPoint.proceed();  //继续执行被拦截方法
    }
}

Filter

• 用法
  实现Filter接口，或继承其实现类
  (eg: GenericFilterBean -> OncePerRequestFilter -> AbstractRequestLoggingFilter)

    @Component
    public class MyFilter implements Filter {
        private Logger logger = LoggerFactory.getLogger(getClass());
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
        }
        @Override
        public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
            // do something
            chain.doFilter(request, response); //继续执行 
        }     
        @Override    
        public void destroy() {        
        }

转载于:https://www.jianshu.com/p/fbde79d76709