技术要点：
1、如何获取业务系统中用户身份标识。
OPENID是微信公众号中用户的唯一标识，通过OPENID与业务系统中USRID建立一对一的对应关系，这样获取到了OPENID也就能知道所对应的USRID，从而获取对应权限的业务数据。
OPENID获取地址：
https://api./sns/oauth2/access_token?appid=APPID&secret=APPSECRET&code=CODE&grant_type=authorization_code
2、OPENID如何在页面建传递
由于请求获取OPENID是一个耗时的操作，为了加速页面响应速度，提升用户体验，不可能在每个页面中都请求一次。那么怎么保存传递这个OPENID呢，一种方法是用户首次访问时，调用微信接口获取OPENID，然后将OPENID写入服务器端的Cookies，通过Cookie进行OPENID信息传递。下面讲解这种方式具体实施：
（1）添加拦截器，拦截需要获取OPENID进行身份识别的controller，判断请求的cookies信息中是否含有openid，如果有直接放行，否则转向获取OPENID的url。
* <P>微信相关请求拦截器</P>* * @version 1.0* @author wangpf* @date 5月2日 下午7:07:39*/public class OAuth2Interceptor extends HandlerInterceptorAdapter {/*** 日志对象*/protected Logger logger = LoggerFactory.getLogger(getClass());// 从配置文件中读取域名public static String domainUrl = Global.getConfig("wechat_domain_url");public static String domain = "http://"+Global.getConfig("wechat_domain");public boolean preHandle(HttpServletRequest request,HttpServletResponse response, Object handler) throws Exception {String uri = request.getRequestURI();logger.debug("OAuth2Interceptor:"+uri);//兼容旧菜单url，直接放行String code = request.getParameter("code");if(StringUtils.isNotEmpty(code)) {return true;}//判断cookie中是否有openid，没有则转向获取openid的urlCookie[] cookies = request.getCookies();String openid = null;// 判断cookie中是否存在openid 若存在则直接跳过，不存在则获取一次if (cookies != null) {for (Cookie cookie : cookies) {if (cookie.getName().equals("openid")) {openid = cookie.getValue();}}}if (StringUtils.isEmpty(openid)) {response.sendRedirect(domainUrl + "/f/wechat/oauth/oauth2Api?resultUrl=" + domain+ uri);return false;} else {return true;}}public void postHandle(HttpServletRequest request,HttpServletResponse response, Object handler,ModelAndView modelAndView) throws Exception {}public void afterCompletion(HttpServletRequest request,HttpServletResponse response, Object handler, Exception ex)throws Exception {}}
该Controller为获取微信用户OPENID的核心Controller，首次访问时调用微信接口获取OPENID，然后设置cookie到客户端（Cookie userCookie=new Cookie("openid",openid)）。设置cookie过期时间为负数，表明当用户关闭浏览器的时候自动清空cookie。之后的用户请求可以直接从cookie中获取openid。
/*** <P>获取/保存OPENID相关Controller</P>* * @version 1.0* @author wangpf* @date 5月2日 下午7:20:38*/@Controller@RequestMapping(value = "${frontPath}/wechat/oauth")public class OAuth2Controller extends BaseController {//从配置文件获取主域名public static String domainUrl = Global.getConfig("wechat_domain_url");/*** 拼装并转向获取OPENID的url* 示例：* https://open./connect/oauth2/authorize?appid=wx74dfe3afa0ebafe3* &redirect_uri=/evcg/f/wechat/qrcode?response_type=code* &scope=snsapi_base&state=1#wechat_redirect* * @param request* @param resultUrl* @return*/@RequestMapping(value ="oauth2Api")public String oauth2API(HttpServletRequest request, @RequestParam String resultUrl) {StringBuffer redirectUrl = new StringBuffer();if (resultUrl != null) {String backUrl = domainUrl+"/f/wechat/oauth/oauth2MeUrl?oauth2url="+resultUrl;String appid = Global.getConfig("wechat_appid");//组装获取OPENID的urlredirectUrl.append("https://open./connect/oauth2/authorize?");redirectUrl.append("appid=").append(appid);redirectUrl.append("&redirect_uri=").append(backUrl);redirectUrl.append("&response_type=code");redirectUrl.append("&scope=snsapi_base&state=1#wechat_redirect");}//转向获取OPENID的urlreturn "redirect:" + redirectUrl.toString();}/*** 获取微信用户标识OPENID* @param request* @param response* @param code* @param oauth2url* @return*/@RequestMapping(value = "oauth2MeUrl")public String oauth2MeUrl(HttpServletRequest request,HttpServletResponse response, @RequestParam String code, @RequestParam String oauth2url) {try {request.setCharacterEncoding("utf-8");response.setCharacterEncoding("utf-8");HttpSession session = request.getSession();session.setAttribute("code",code);//通过code获取微信用户openid存储在cookie中的信息String openid = WeixinUtil.getOpenId(code);Cookie userCookie=new Cookie("openid",openid);userCookie.setMaxAge(-1);userCookie.setPath("/");response.addCookie(userCookie);} catch (Exception e) {e.printStackTrace();}//转向原始请求urlreturn "redirect:" + oauth2url;}}
