SpringMVC的拦截器

Controller层的拦截器继承于HandlerInterceptorAdapter

HandlerInterceptorAdapter.java 代码如下

public abstract class HandlerInterceptorAdapter implements HandlerInterceptor {
 
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)throws Exception {
    　　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 {

    }
 
}

Spring拦截器通过重写这三个方法实现Controller的拦截。

 public class ControllerInterceptor extends HandlerInterceptorAdapter {
 
 
 　　public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
　　　　 System.out.println("ControllerInterceptor.preHandle()");
　　　　 return true;
　　 }
 
 
　　 public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
 　　　　System.out.println("ControllerInterceptor.postHandle()");
　　}
 
 
 　　public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
 　　　　System.out.println("ControllerInterceptor.afterCompletion()");
　　 }
 }

配置拦截器

<bean id="handlerMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">
　　<property name="interceptors">
　　　　<list>
　　　　　　<ref bean="controllerInterceptor" />
　　　　</list>
　　</property>
　　<property name="mappings">
　　　　<props>
　　　　　　<prop key="/hao/hello.do">helloWorldController</prop>
　　　　</props>
　　</property>
</bean>
 
<bean id="controllerInterceptor" class="com.web.spring.mvc.interceptor.ControllerInterceptor"/>

测试代码HelloWorldController.java

@Controller
@RequestMapping("/hao")
public class HelloWorldController {
 
　　@RequestMapping(value = "/hello")
　　public String hello(HttpServletRequest request, HttpServletResponse response) {
　　　　System.out.println("hello");
　　　　return "helloWorld";
　　}
}

说明：
发起请求,进入拦截器链，运行所有拦截器的preHandle方法，
1.当preHandle方法返回false时，从当前拦截器往回执行所有拦截器的afterCompletion方法，再退出拦截器链。
2.当preHandle方法全为true时，执行下一个拦截器,直到所有拦截器执行完。再运行被拦截的Controller。然后进入拦截器链，运行所有拦截器的postHandle方法,完后从最后一个拦截器往回执行所有拦截器的afterCompletion方法.
当有拦截器抛出异常时,会从当前拦截器往回执行所有拦截器的afterCompletion方法