package com.cy.example.config;

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

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

public class LoginInterceptor implements HandlerInterceptor {

  private Logger logger = LoggerFactory.getLogger(LoginInterceptor.class);

  public void postHandle(HttpServletRequest request,
      HttpServletResponse response, Object handler,
      ModelAndView modelAndView) throws Exception {
    // TODO Auto-generated method stub

  }

  public void afterCompletion(HttpServletRequest request,
      HttpServletResponse response, Object handler, Exception ex)
      throws Exception {
    // TODO Auto-generated method stub

  }

  public boolean preHandle(HttpServletRequest request,
      HttpServletResponse response, Object handler) throws Exception {
    // TODO Auto-generated method stub
    //獲取session
    HttpSession session = request.getSession(true);
    logger.info("----進入登錄攔截器--url："+request.getServletPath()+"-----");
    if(session.getAttribute(WebConfig.LOGIN_USER) == null){
      logger.info("------跳轉(zhuǎn)到login頁面-----");
      response.sendRedirect(request.getContextPath()+"/index");
      return false;
    }else{
      session.setAttribute(WebConfig.LOGIN_USER, session.getAttribute(WebConfig.LOGIN_USER));
      return true;
    }
  }

}

package com.cy.example.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.DefaultServletHandlerConfigurer;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ResourceHandlerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

@Configuration
public class WebConfig extends WebMvcConfigurerAdapter {

  public static String LOGIN_USER = "loginUser";

  public WebConfig() {
    super();
  }
  //因為新加了攔截器，這里需要重新設置資源地址
  @Override
  public void addResourceHandlers(ResourceHandlerRegistry registry) {
    registry.addResourceHandler("/static/**").addResourceLocations(
        "classpath:/static/");
    registry.addResourceHandler("/templates/**").addResourceLocations(
        "classpath:/templates/");

    super.addResourceHandlers(registry);
  }

  @Override
  public void configureDefaultServletHandling(
      DefaultServletHandlerConfigurer configurer) {
    configurer.enable();
  }

  @Override
  public void addInterceptors(InterceptorRegistry registry) {
    // 攔截規(guī)則：除了login，其他都攔截判斷,excludePathPatterns是排除攔截的路徑，一個是登錄驗證地址，一個是登錄頁
    registry.addInterceptor(new
LoginInterceptor()).addPathPatterns("/**").excludePathPatterns("/index","/system/user/validate");
    super.addInterceptors(registry);
  }

}