preHandle:?預先處理,在目標的controller方法執行之前,進行處理

postHandle:?在目標的controller方法執行之后,到達指定頁面之前進行處理

afterCompletion:?在頁面渲染之后進行處理

方法:

1.Springboot通過實現HandlerInterceptor接口實現攔截器

2.通過WebMvcConfigurer實現一個配置類,再通過@Configuration 注解注入到容器

3.指定攔截規則

?以用戶登錄為案例,若用戶沒有登錄session里面就沒有用戶的數據,就會轉到首頁登錄頁面

在正確登錄之后，就將reglister保存到session中，再次訪問頁面的時候，登錄攔截器就可以找到這個reglister對象，就不需要再次攔截到登錄界面了.

package com.zwz.springbootweb.interceptor;import org.springframework.context.annotation.Bean; import org.springframework.stereotype.Component; import org.springframework.stereotype.Service; import org.springframework.web.servlet.HandlerInterceptor; import org.springframework.web.servlet.ModelAndView;import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import javax.websocket.Session;public class LoginInterceptor implements HandlerInterceptor {@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {HttpSession session = request.getSession();Object reglister = session.getAttribute("Reglister");if (reglister != null) {return true;} else {request.setAttribute("msg", "請先登錄!");request.getRequestDispatcher("/").forward(request,response);return false;}}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {HandlerInterceptor.super.afterCompletion(request, response, handler, ex);} }

?

?之后通過實現WebMvcConfigurer接口實現一個配置類，在配置類中注入攔截器，最后再通過 @Configuration 注解注入配置.并且指定攔截的路徑和需要放行的路徑.

注意:攔截器? /**? ?會攔截一切資源,包括靜態資源,需要將靜態資源放行

?

package com.zwz.springbootweb.config;import com.zwz.springbootweb.interceptor.LoginInterceptor; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.web.filter.HiddenHttpMethodFilter; import org.springframework.web.servlet.config.annotation.InterceptorRegistry; import org.springframework.web.servlet.config.annotation.PathMatchConfigurer; import org.springframework.web.servlet.config.annotation.WebMvcConfigurer; import org.springframework.web.util.UrlPathHelper;@Configuration public class WebConfig implements WebMvcConfigurer{@Overridepublic void addInterceptors(InterceptorRegistry registry) {registry.addInterceptor(new LoginInterceptor()).addPathPatterns("/**").excludePathPatterns("/loginjudge","/","/retolo","/static/**");}}

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