本文主要是介绍Spring中的拦截器、过滤器与切面，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
（一）概念
| 类别 | 拦截器 | 过滤器 | 切面 |
|---|---|---|---|
| 包 | HandlerInterceptor 接口在 org.springframework.web.servlet | Filter 接口在 javax.servlet | @Aspect注解在 org.aspectj.lang.annotation |
| 配置 | @Component,然后需要在WebMvcConfigurerAdapter注册拦截器 | 需要在web.xml中配置(或是@Component或是@Configuration搭配@Bean) | @Aspect 、@Component |
| 使用范围 | 拦截器能用于所有Spring为容器的应用中，可以获取所有Spring容器中的资源 | 过滤器在servlet前后被调用，不能获取spring容器中的所有资源 | 切面围绕着方法而定义 |
| 局限性 | 可以获取调用类，调用方法，访问不了参数的值 | 可以获取request相关参数，不能访问当前控制器调用类，方法，参数值 | 可以获取调用类，调用方法，还能获取参数的值，不能获取request的相关参数 |
在Spring作为容器管理的应用中，推荐使用拦截器。能够提供比过滤器更强大的功能。
调用时序：
（二）过滤器
过滤器的两种声明方式：
①实现接口Filter,并用注解@Component声明为Spring容器中的组件：
@Component
public class MyFilter implements Filter {//所有的请求都会过这个过滤器@Overridepublic void init(FilterConfig filterConfig) throws ServletException {System.out.println("Init Filter!");}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {System.out.println("Do Filter!");long startTime = System.currentTimeMillis();filterChain.doFilter(servletRequest,servletResponse);System.out.println("过滤器执行的时间："+(System.currentTimeMillis() - startTime));}@Overridepublic void destroy() {System.out.println("Destroy Filter!");}
}
②实现接口Filter，在@Configuration注解的类中配置filter bean：
public class MyFilterWithoutComponent implements Filter {@Overridepublic void init(FilterConfig filterConfig) throws ServletException {System.out.println("Init FilterWithoutComponent!");}@Overridepublic void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {System.out.println("Do FilterWithoutComponent!");long startTime = System.currentTimeMillis();filterChain.doFilter(servletRequest,servletResponse);System.out.println("非@Component注解的过滤器执行的时间："+(System.currentTimeMillis() - startTime));}@Overridepublic void destroy() {System.out.println("Destroy FilterWithoutComponent!");}
}
配置bean：
/*** 相当于web.xml*/
@Configuration
public class WebConfig{@Beanpublic FilterRegistrationBean myFilter(){FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();MyFilterWithoutComponent myFilterWithoutComponent = new MyFilterWithoutComponent();filterRegistrationBean.setFilter(myFilterWithoutComponent);List<String > urls = new ArrayList<>();urls.add("/user/*");//只有满足的url才会进入以上指定的过滤器filterRegistrationBean.setUrlPatterns(urls);return filterRegistrationBean;}
}
（三）拦截器
声明拦截器需要：实现接口HandlerInterceptor ，并使@Configuration注解的配置类实现接口WebMvcConfigurerAdapter，重写addInterceptors方法，来注册拦截器。
@Component
public class MyInterceptor implements HandlerInterceptor {/*** 调用请求之前* @param httpServletRequest* @param httpServletResponse* @param o* @return* @throws Exception*/@Overridepublic boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {System.out.println("Interceptor preHandle Start");System.out.println(("调用类为："+((HandlerMethod)o).getBean().getClass().getName()));System.out.println(("调用方法为："+((HandlerMethod)o).getMethod().getName()));httpServletRequest.setAttribute("startTime", System.currentTimeMillis());return true;//true:继续执行postHandler false：不会执行interceptor的其他方法}/*** 调用请求时(仅成功时)* @param httpServletRequest* @param httpServletResponse* @param o* @param modelAndView* @throws Exception*/@Overridepublic void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {long startTime = (long)httpServletRequest.getAttribute("startTime");System.out.println("Interceptor postHandle start!");System.out.println("postHandler执行了"+(System.currentTimeMillis()-startTime));}/*** 调用结束后(无论成功失败)* @param httpServletRequest* @param httpServletResponse* @param o* @param e* @throws Exception*/@Overridepublic void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {System.out.println("Interceptor afterCompletion!");long startTime = (long)httpServletRequest.getAttribute("startTime");System.out.println("afterCompletion执行了"+(System.currentTimeMillis()-startTime));//System.out.println("afterCompletion-exception:"+e.getMessage());}
}
配置类：
@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {@Autowiredprivate MyInterceptor myInterceptor;@Overridepublic void addInterceptors(InterceptorRegistry registry) {//拦截器必须在此注册registry.addInterceptor(myInterceptor);}
}
（四）切面
AOP详细知识可以参考Spring AOP – 使用总结
@Aspect
@Component
public class MyAspect {@Around("execution(* com.funnee.security.controller.UserController.*(..))")public Object handleController(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {System.out.println("Aspect start up!");Object[] args = proceedingJoinPoint.getArgs();for(Object arg:args){System.out.println("arg:"+arg);}System.out.println("Aspect finished!");return proceedingJoinPoint.proceed(args);}
}
（五）测试
分别声明拦截器，过滤器，切面，访问 user/1 GET:
Do FilterWithoutComponent!
Interceptor preHandle Start
调用类为：com.funnee.security.controller.UserController$$EnhancerBySpringCGLIB$$1a184af4
调用方法为：getUserInfo
Aspect start up!
arg:1
Aspect finished!
获取用户信息API正常执行(Controller中的日志)
Interceptor postHandle start!
postHandler执行了80
Interceptor afterCompletion!
afterCompletion执行了80
非@Component注解的过滤器执行的时间：102
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