SrpingMVC拦截器HandlerInterceptorAdapter

不念不忘少年蓝@ 2022-04-05 08:16 177阅读 0赞

### SrpingMVC拦截器HandlerInterceptorAdapter ###

--------------------

HandlerInterceptorAdapter 可以在 controller 请求前、controller处理后response返回前、response返回结束后进项扩展。

HandlerInterceptorAdapter 是个适配器 ，实现了 HandlerInterceptor 接口。这里适配的好处是，不用重写接口的所有方法，只需要根据自己的需要，重写个别方法即可。

public interface HandlerInterceptor { 
    
    	boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    	    throws Exception;
        
    	void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
    			throws Exception;
    
    	void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
    			throws Exception;
    
    }

HandlerInterceptorAdapter 实现了接口的全部方法，返回void的什么也不做. preHandle 方法返回boolean, true的时候程序继续执行，false的时候停止执行后续的拦截器和访问controller， 直接返回response。 所以适配器抽象类默认返回true, 如果不需要重写此方法也让程序正常运行不受影响。

public abstract class HandlerInterceptorAdapter implements AsyncHandlerInterceptor { 
    
    	@Override
    	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
    		throws Exception { 
    		return true;
    	}
    
    	@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 { 
    	}
    
    	@Override
    	public void afterConcurrentHandlingStarted(
    			HttpServletRequest request, HttpServletResponse response, Object handler)
    			throws Exception { 
    	}
    
    }

spring 配置的多个拦截器，preHandle（） 拦截的顺序是声明的顺序。postHandle（） 和 afterCompletion（）是逆序的，想想也是很合理的。下面举个例子

<mvc:interceptors>
        
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean id="authInterceptor" class="com.blink.eye.web.AuthInterceptor" />
        </mvc:interceptor>
        
        <mvc:interceptor>
            <mvc:mapping path="/**"/>
            <bean id="logInterceptor" class="com.blink.eye.web.LogInterceptor" />
        </mvc:interceptor>
    </mvc:interceptors>

public class AuthInterceptor extends HandlerInterceptorAdapter { 
    
        Map<String, String> userInfo = new HashMap<>();
    
        private static final AuthFailVO AUTH_FAILED = new AuthFailVO("00000000", "请先登录");
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { 
            if (handler instanceof HandlerMethod) { 
                HandlerMethod handlerMethod = (HandlerMethod) handler;
                if (AnnotatedElementUtils.isAnnotated(handlerMethod.getMethod(), NonLogin.class)
                        || AnnotatedElementUtils.isAnnotated(handlerMethod.getBeanType(), NonLogin.class)) { 
                    log.info("不需要登陆");
                    return true;
                }
            }
            boolean b = request.isRequestedSessionIdValid();
            if (b) { 
                return true;
            }
            log.error("认证不通过");
            response.reset();
            response.setStatus(HttpStatus.UNAUTHORIZED.value());
            response.setContentType("application/json");
            response.getOutputStream().write(JSON.toJSONString(AUTH_FAILED).getBytes("utf-8"));
            return false;
        }
    
    
        @Override
        public void postHandle(
                HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)  { 
            log.info("登录结束，但还没返回前端");
        }
    
        @Override
        public void afterCompletion(
                HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)  { 
            log.info("登录结束，并且返回");
        }
    
    }

public class LogInterceptor extends HandlerInterceptorAdapter { 
    
        private ThreadLocal<Long> longLocal = new ThreadLocal<>();
    
        private ThreadLocal<String> stringLocal = new ThreadLocal<>();
    
        @Override
        public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)  { 
            HandlerMethod method = (HandlerMethod) handler;
            log.info("方法：{} 开始时间：{}", method.getMethod(), System.currentTimeMillis());
            longLocal.set(System.currentTimeMillis());
            stringLocal.set(method.getMethod().getName());
            return true;
        }
    
        @Override
        public void postHandle(
                HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)  { 
            log.info("方法 {} 执行耗时：{} ms", stringLocal.get(), System.currentTimeMillis() - longLocal.get());
        }
    
        @Override
        public void afterCompletion(
                HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)  { 
            log.info("接口方法 {} 结束", stringLocal.get(), System.currentTimeMillis() - longLocal.get());
        }
    
    }

两个拦截器都是拦截所有请求，登陆以后，打印日志信息可以比较清晰的看到拦截器各个方法执行的顺序。

com.blink.eye.web.AuthInterceptor.preHandle:34 -不需要登陆
    com.blink.eye.web.LogInterceptor.preHandle:25 -方法：public java.lang.String com.blink.eye.web.PortalController.login(javax.servlet.http.HttpServletRequest) 开始时间：1544516281353
    com.blink.eye.web.LogInterceptor.postHandle:34 -方法 login 执行耗时：165 ms
    com.blink.eye.web.AuthInterceptor.postHandle:54 -登录结束，但还没返回前端
    com.blink.eye.web.LogInterceptor.afterCompletion:40 -接口方法 login 结束
    com.blink.eye.web.AuthInterceptor.afterCompletion:60 -登录结束，并且返回