Spring MVC 框架中不使用xml實現攔截器(HandlerInterceptor)登入

當要架設需要使用者先登入才能進行其他操作的網站時，

要建立攔截器(HandlerInterceptor)並註冊進Spring MVC中。

首先，建立攔截器：

建立class，繼承HandlerInterceptor這個攔截器介面。
在preHandle方法內判定session是否有會員的資訊

@Component
public class AuthorizationInterceptor implements HandlerInterceptor {

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
throws Exception {
System.out.println("---AuthorizationInterceptor preHandle---");

if (request.getSession().getAttribute("emp") != null) {
return true;
} else {
response.sendRedirect(request.getContextPath() + "/login");
return false;
}
}

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
System.out.println("---AuthorizationInterceptor postHandle---");
}

@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
System.out.println("---AuthorizationInterceptor afterCompletion---");
}

}

接著，加入要過濾的請求及排除白名單

建立WebAppConfig這個class，繼承WebMvcConfigurer 

addPathPatterns("/*")表示攔截所有請求

excludePathPatterns("/login")表示只讓/login這個視圖名稱的請求通過(白名單)

@Configuration

@EnableWebMvc

@ComponentScan("你的專案名稱")

public class WebAppConfig implements WebMvcConfigurer {

        

        @Autowired

private AuthorizationInterceptor authorizationInterceptor;

@Override

public void addInterceptors(InterceptorRegistry registry) {

registry.addInterceptor(authorizationInterceptor).

addPathPatterns("/*").excludePathPatterns("/login");

}

}

這樣就能先登入才能做其它事囉！