一般情況下，對(duì)來(lái)自瀏覽器的請(qǐng)求的攔截，是利用Filter實(shí)現(xiàn)的，這種方式可以實(shí)現(xiàn)Bean預(yù)處理、后處理。? Spring MVC的攔截器不僅可實(shí)現(xiàn)Filter的所有功能，還可以更精確的控制攔截精度。?

Spring為我們提供了org.springframework.web.servlet.handler.HandlerInterceptorAdapter這個(gè)適配器，繼承此類(lèi)，可以非常方便的實(shí)現(xiàn)自己的攔截器。他有三個(gè)方法：

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[java]?view plain?copy

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?{????

????}????

分別實(shí)現(xiàn)預(yù)處理、后處理（調(diào)用了Service并返回ModelAndView，但未進(jìn)行頁(yè)面渲染）、返回處理（已經(jīng)渲染了頁(yè)面）?
在preHandle中，可以進(jìn)行編碼、安全控制等處理；?
在postHandle中，有機(jī)會(huì)修改ModelAndView；?
在afterCompletion中，可以根據(jù)ex是否為null判斷是否發(fā)生了異常，進(jìn)行日志記錄。?

如果基于xml配置使用Spring MVC，
可以利用SimpleUrlHandlerMapping、BeanNameUrlHandlerMapping進(jìn)行Url映射（相當(dāng)于struts的path映射）和攔截請(qǐng)求（注入interceptors），
如果基于注解使用Spring MVC，可以使用DefaultAnnotationHandlerMapping注入interceptors。
注意無(wú)論基于xml還是基于注解，HandlerMapping bean都是需要在xml中配置的。?

一個(gè)demo：?
在這個(gè)例子中，我們假設(shè)UserController中的注冊(cè)操作只在9：00-12：00開(kāi)放，那么就可以使用攔截器實(shí)現(xiàn)這個(gè)功能。?

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[java]?view plain?copy

public?class?TimeBasedAccessInterceptor?extends?HandlerInterceptorAdapter?{????

????private?int?openingTime;????

????private?int?closingTime;????

????private?String?mappingURL;//利用正則映射到需要攔截的路徑????

????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",?"注冊(cè)開(kāi)放時(shí)間：9：00-12：00");????

????????????????request.getRequestDispatcher("/msg.jsp").forward(request,?response);????

????????????????return?false;????

????????????}????

????????????return?true;????

????????}????

????????return?true;????

????}????

}????

xml配置：?

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[html]?view plain?copy

<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>????

這里我們定義了一個(gè)mappingURL屬性，實(shí)現(xiàn)利用正則表達(dá)式對(duì)url進(jìn)行匹配，從而更細(xì)粒度的進(jìn)行攔截。當(dāng)然如果不定義mappingURL，則默認(rèn)攔截所有對(duì)Controller的請(qǐng)求。?

UserController：?

?

?

[java]?view plain?copy

@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?...????

}????

這個(gè)Controller相當(dāng)于Struts的DispatchAction?

你也可以配置多個(gè)攔截器，每個(gè)攔截器進(jìn)行不同的分工.?

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轉(zhuǎn)載于:https://www.cnblogs.com/lxaic/p/5851985.html

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