SpringMVC拦截器实例之自定义注解

import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;

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

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

public class OAuth2Interceptor implements HandlerInterceptor {

	/**
	 * 在DispatcherServlet完全处理完请求后被调用
	 * 当有拦截器抛出异常时,会从当前拦截器往回执行所有的拦截器的afterCompletion()
	 */
	@Override
	public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
		System.out.println("**执行顺序: 3、afterCompletion**");

	}

	/**
	 * 在业务处理器处理请求执行完成后,生成视图之前执行的动作
	 */
	@Override
	public void postHandle(HttpServletRequest request, HttpServletResponse response, Object arg2, ModelAndView modelAndView) throws Exception {
		System.out.println("**执行顺序: 2、postHandle**");

	}

	/**
	 * 在业务处理器处理请求之前被调用 如果返回false 从当前的拦截器往回执行所有拦截器的afterCompletion(),再退出拦截器链
	 * 如果返回true 执行下一个拦截器,直到所有的拦截器都执行完毕 再执行被拦截的Controller 然后进入拦截器链,
	 * 从最后一个拦截器往回执行所有的postHandle() 接着再从最后一个拦截器往回执行所有的afterCompletion()
	 */
	@Override
	public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
		System.out.println("**执行顺序: 1、preHandle**");
		String url = request.getRequestURL().toString();

		HttpSession session = request.getSession();
		// 先判断是否有注解

		HandlerMethod handlerMethod = (HandlerMethod) handler;
		Method method = handlerMethod.getMethod();
		OAuthRequired annotation = method.getAnnotation(OAuthRequired.class);
		if (annotation != null) {
			System.out.println("OAuthRequired：你的访问需要获取登录信息！");
			Object objUid = session.getAttribute("UserId");
			if (objUid == null) {
				String resultUrl = request.getRequestURL().toString();
				String param=request.getQueryString();
				if(param!=null){
					resultUrl+= "?" + param;
				}
				System.out.println("resultUrl="+resultUrl);
				try {
					resultUrl = java.net.URLEncoder.encode(resultUrl, "utf-8");
				} catch (UnsupportedEncodingException e) {
					e.printStackTrace();
				}
				//请求的路径
		        String contextPath=request.getContextPath();
				response.sendRedirect(contextPath + "/oauth2.do?resultUrl=" + resultUrl);
				return false;
			}

		}
		return true;
	}

}