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;
}

}