在SpringBoot框架中使用拦截器

1.继承WebMvcConfigureAdapter类，覆盖其addInterceptors接口,注册我们自定义的拦截器

 package com.eth.wallet.config;

 import com.eth.wallet.interceptor.MyInterceptor;
 import org.springframework.boot.SpringBootConfiguration;
 import org.springframework.web.servlet.config.annotation.*;

 /**
  * @CLassName WebAppConfig
  * @Description TODO
  * @Author wangpengfei
  * @Email wangpengfei4113@163.com
  * @Date 2018/12/3 17:40
  * @Version 1.0
  **/
 @SpringBootConfiguration
 public class WebAppConfig extends WebMvcConfigurerAdapter {

    /**
     * 注册拦截器
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
       //addPathPattern后跟拦截地址，excludePathPatterns后跟排除拦截地址
       registry.addInterceptor(new MyInterceptor()).addPathPatterns("/**")
             .excludePathPatterns("/WalletUser/toLogin")
             .excludePathPatterns("/WalletUser/toRegister")
             .excludePathPatterns("/WalletUser/login");
    }
 }

2.实现HandlerInterceptor接口，重写接口中的三个方法

package com.eth.wallet.interceptor;

/**
 * @CLassName MyInterceptor
 * @Description TODO
 * @Author wangpengfei
 * @Email wangpengfei4113@163.com
 * @Date 2018/12/3 17:44
 * @Version 1.0
 **/
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
/**
 * 拦截器
 */
@Component
public class MyInterceptor implements HandlerInterceptor{
    //在请求处理之前进行调用（Controller方法调用之前
    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        HttpSession session = httpServletRequest.getSession();
        //获取登录的session信息
        String user = (String) session.getAttribute("user");
        if(user!=null){
            return true;
        }
        else{
            //未登录自动跳转界面
            httpServletResponse.sendRedirect(httpServletRequest.getContextPath()+"/WalletUser/toLogin");
            return false;
        }
    }

    //请求处理之后进行调用，但是在视图被渲染之前（Controller方法调用之后）
    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

        System.out.println("postHandle被调用\n");
    }

    //在整个请求结束之后被调用，也就是在DispatcherServlet 渲染了对应的视图之后执行（主要是用于进行资源清理工作）
    @Override
    public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {
        System.out.println("afterCompletion被调用\n");
    }
}