淺析java中 Spring MVC 攔截器作用及其實(shí)現(xiàn)

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
 
public class TestInterceptor implements HandlerInterceptor {
 /**
  * 返回值說明是否需要將當(dāng)前的請求攔截下來
  * false：請求將被終止
  * true：請求會被繼續(xù)運(yùn)行
  * Object handler 表示的是被攔截的請求的目標(biāo)對象
  */
 @Override
 public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
   throws Exception {
  System.out.println("TestInterceptor.preHandle()");
  return true;
 }
 /**
  * modelAndView：
  *  可以通過modelAndView參數(shù)改變顯示的視圖，或者修改發(fā)往視圖的方法
  */
 @Override
 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler,
   ModelAndView modelAndView) throws Exception {
  System.out.println("TestInterceptor.postHandle()"); 
 }
 /**
  * 在視圖加載完畢之后調(diào)用
  * 常用于作于資源的銷毀，流等
  * 類似于析構(gòu)函數(shù)
  */
 @Override
 public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
   throws Exception {
  System.out.println("TestInterceptor.afterCompletion()"); 
 }
}

<!-- 注冊攔截器 -->
 <mvc:interceptors>
 <!-- 單個(gè)攔截器:設(shè)置具體的攔截路徑 -->
 <mvc:interceptor>
  <mvc:mapping path="/courses/view2/*">
  <bean class="com.cc.mvcdemo.interceptor.TestInterceptor"></bean>
 </mvc:mapping></mvc:interceptor>
 <!-- 第二種方式：攔截經(jīng)過當(dāng)前Dispatcherservlet的所有請求 -->
 <bean class="com.cc.mvcdemo.interceptor.TestInterceptorTwo"></bean>
 </mvc:interceptors>