package com.leiyuan.bs.interceptor;

import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// 攔截器
public class MyHandlerInterceptor implements HandlerInterceptor {
  /**
   * 攔截（Controller方法調用之前）
   *
   * @param request request
   * @param response response
   * @param o    o
   * @return 通過與否
   * @throws Exception 異常處理
   */
  @Override
  public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object
      o) throws Exception {
    // TODO 我這里是通過用戶是否登陸進行攔截，我的用戶信息存儲在session中，名稱為userSession，大家可以自行實現
    if (request.getSession().getAttribute("userSession") == null) {
      // 攔截至登陸頁面
      request.getRequestDispatcher("/user/toLogin").forward(request, response);
      // false為不通過
      return false;
    }
    // true為通過
    return true;
  }

  // 此方法為處理請求之后調用（調用過controller方法之后，跳轉視圖之前）
  @Override
  public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o,
              ModelAndView modelAndView) throws Exception {

  }

  // 此方法為整個請求結束之后進行調用
  @Override
  public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse,
                Object o, Exception e) throws Exception {

  }
}

package com.leiyuan.bs;

import com.leiyuan.bs.interceptor.MyHandlerInterceptor;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;
// 攔截器配置類
@Component
public class MyHandlerInterceptorConfig extends WebMvcConfigurerAdapter {
  @Override
  public void addInterceptors(InterceptorRegistry registry) {
  	/**
     * 這里的addPathPatterns("/**")為配置需要攔截的方法“/**”代表所有，而后excludePathPatterns("/user/toLogin")等方法為排除哪些方法不進行		 攔截
     */
    registry.addInterceptor(new MyHandlerInterceptor()).addPathPatterns("/**").excludePathPatterns("/user/toLogin").excludePathPatterns
        ("/user/login").excludePathPatterns("/user/toNewUser").excludePathPatterns("/user/newUser");
    super.addInterceptors(registry);
  }
}