SpringBoot自定义拦截器

SpringMVC具有统一的入口DispatcherServlet，所有的请求都通过DispatcherServlet。
    DispatcherServlet是前置控制器，配置在web.xml文件中的。拦截匹配的请求，Servlet拦截匹配规则要自已定义，把拦截下来的请求，依据某某规则分发到目标Controller来处理。
SpringMVC的拦截器HandlerInterceptor接口对应提供了三个preHandle，postHandle，afterCompletion方法。preHandle在业务处理器处理请求之前被调用，
    postHandle在业务处理器处理请求执行完成后,生成视图之前执行，afterCompletion在DispatcherServlet完全处理完请求后被调用,可用于清理资源等。

在SpringBoot中使用拦截器首先需要实现HandlerInterceptor接口，然后将拦截器注册到MVC中，由MVC根据请求来执行不同的拦截器。

第一步：创建拦截器

package com.bjqdl.wzy.web.interceptors;

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

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

import com.bjqdl.wzy.core.ThreadLocalMap;
import com.bjqdl.wzy.core.UserContext;
import com.bjqdl.wzy.util.AssertUtil;
import com.bjqdl.wzy.util.json.JSONUtil;
import com.bjqdl.wzy.web.entity.User;
import com.bjqdl.wzy.web.service.UserInfoService;
import com.bjqdl.wzy.web.utils.HttpUtils;

public class UserInfoInterceptor implements HandlerInterceptor{

	private static final Logger logger = LoggerFactory.getLogger(UserInfoInterceptor.class);
	
	private UserInfoService userInfoService;
	public UserInfoInterceptor(UserInfoService userInfoService) {
		super();
		this.userInfoService = userInfoService;
	}

	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
			throws Exception {
		logger.debug("UserInfoInterceptor.preHandle");
		String openid = request.getParameter("openid");
		if (request.getRequestURL().toString().contains("/user/")){
			logger.debug("注册用户!");
			return true;
		}
		if (!AssertUtil.isVal(openid)) {
			logger.error("用户信息不完整，请在url后追加用户信息 url?openid=xxxx");
			return false;
		}
		if (openid.equals(UserContext.getOpenID())) {
			return true;
		}
		ThreadLocalMap.reset();
		User user = this.userInfoService.getUser(openid);
		if (AssertUtil.isVal(user)) {
			ThreadLocalMap.put(UserContext.USER_CONTEXT, JSONUtil.parseJSON(user));
			ThreadLocalMap.put(UserContext.USER_CONTEXT_IP, HttpUtils.getIpAddress(request));
			return true;
		} else {
			return false;
		}
	}

	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
			ModelAndView modelAndView) throws Exception {
		
	}

	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception {
	}

	
}

第二步：注册到MVC中

自定义MVCConfig类，继承WebMvcConfigurerAdapter类，重现public void addInterceptors(InterceptorRegistry registry)方法，具体实现见代码

package com.bjqdl.wzy.web.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import com.bjqdl.wzy.web.interceptors.UserInfoInterceptor;
import com.bjqdl.wzy.web.service.UserInfoService;

@Configuration
public class MVCConfig extends WebMvcConfigurerAdapter {

	
	@Autowired
	private UserInfoService userInfoService;
	
	/* (non-Javadoc)
	 * @see org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter#addInterceptors(org.springframework.web.servlet.config.annotation.InterceptorRegistry)
	 */
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		registry.addInterceptor(new UserInfoInterceptor(userInfoService)).addPathPatterns("/**");
		super.addInterceptors(registry);
	}

}

注意：

         1、注解@Configuration是必备的；

         2、addPathPatterns("/**");方法用于通知过滤器针对那些url进行拦截