springmvc的HandlerInterceptorAdapter拦截器

Spring MVC的拦截器不仅可实现Filter的所有功能，还可以更精确的控制拦截精度。 spring为我们提供了org.springframework.web.servlet.handler.HandlerInterceptorAdapter这个适配器，继承此类，可以非常方便的实现自己的拦截器。
这个类一共有三个方法：

public class BaseInterceptor extends HandlerInterceptorAdapter {

private final static Logger LOGGER = LoggerFactory.getLogger
            (BaseInterceptor.class);

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse
            response, Object handler) throws Exception {
        //your code  
        return super.preHandle(request, response, handler);
    }

@Override
public void postHandle(HttpServletRequest request, HttpServletResponse
            response, Object handler, ModelAndView modelAndView) throws  Exception {
          //your code  
}

@Override
public void afterCompletion(HttpServletRequest request,
    HttpServletResponse response, Object handler,
    Exception ex) throws Exception {
     //your code  
}

分别实现预处理、后处理（调用了Service并返回ModelAndView，但未进行页面渲染）、返回处理（已经渲染了页面）
在preHandle中，可以进行编码、安全控制等处理；
在postHandle中，有机会修改ModelAndView；
在afterCompletion中，可以根据ex是否为null判断是否发生了异常，进行日志记录。

springmvc.xml里面的配置

<mvc:interceptors>
       <mvc:interceptor>
           <mvc:mapping path="/**"/>
           <bean class="com.zz.BaseInterceptor"/>
       </mvc:interceptor>
</mvc:interceptors>

我们假设UserController中的注册操作只在9：00-12：00开放，那么就可以使用拦截器实现这个功能

public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {    
    private int openingTime;    
    private int closingTime;    
    private String mappingURL;//利用正则映射到需要拦截的路径    
    public void setOpeningTime(int openingTime) {    
        this.openingTime = openingTime;    
    }    
    public void setClosingTime(int closingTime) {    
        this.closingTime = closingTime;    
    }    
    public void setMappingURL(String mappingURL) {    
        this.mappingURL = mappingURL;    
    }    
    @Override    
    public boolean preHandle(HttpServletRequest request,    
            HttpServletResponse response, Object handler) throws Exception {    
        String url=request.getRequestURL().toString();    
        if(mappingURL==null || url.matches(mappingURL)){    
            Calendar c=Calendar.getInstance();    
            c.setTime(new Date());    
            int now=c.get(Calendar.HOUR_OF_DAY);    
            if(now<openingTime || now>closingTime){    
                request.setAttribute("msg", "注册开放时间：9：00-12：00");    
                request.getRequestDispatcher("/msg.jsp").forward(request, response);    
                return false;    
            }    
            return true;    
        }    
        return true;    
    }    
}    

<bean id="timeBasedAccessInterceptor" class="com.spring.handler.TimeBasedAccessInterceptor">    
    <property name="openingTime" value="9" />    
    <property name="closingTime" value="12" />    
    <property name="mappingURL" value=".*/user\.do\?action=reg.*" />    
</bean>    
<bean class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">    
    <property name="interceptors">    
        <list>    
            <ref bean="timeBasedAccessInterceptor"/>    
        </list>    
    </property>    
</bean> 

这里我们定义了一个mappingURL属性，实现利用正则表达式对url进行匹配，从而更细粒度的进行拦截。当然如果不定义mappingURL，则默认拦截所有对Controller的请求。

@Controller    
@RequestMapping("/user.do")    
public class UserController{    
    @Autowired    
    private UserService userService;    
    @RequestMapping(params="action=reg")    
    public ModelAndView reg(Users user) throws Exception {    
        userService.addUser(user);    
        return new ModelAndView("profile","user",user);    
    }    
    // other option ...    
}