6.6.2 过滤器的类型 - Reference Documentation
Authors: Graeme Rocher, Peter Ledbrook, Marc Palmer, Jeff Brown, Luke Daley, Burt Beckwith
Version: null
6.6.2 过滤器的类型
Within the body of the filter you can then define one or several of the following interceptor types for the filter:
Here the In this logging example we just log various request information, but note that the
在过滤器的主体内,你可以定义下列过滤器中拦截器类型的一个或者几个:
before- Executed before the action. Returnfalseto indicate that the response has been handled that that all future filters and the action should not executeafter- Executed after an action. Takes a first argument as the view model to allow modification of the model before rendering the viewafterView- Executed after view rendering. Takes an Exception as an argument which will be non-nullif an exception occurs during processing. Note: this Closure is called before the layout is applied.
class SecurityFilters {
def filters = {
loginCheck(controller: '*', action: '*') {
before = {
if (!session.user && !actionName.equals('login')) {
redirect(action: 'login')
return false
}
}
}
}
}loginCheck filter uses a before interceptor to execute a block of code that checks if a user is in the session and if not redirects to the login action. Note how returning false ensure that the action itself is not executed.Here's a more involved example that demonstrates all three filter types:import java.util.concurrent.atomic.AtomicLongclass LoggingFilters { private static final AtomicLong REQUEST_NUMBER_COUNTER = new AtomicLong() private static final String START_TIME_ATTRIBUTE = 'Controller__START_TIME__' private static final String REQUEST_NUMBER_ATTRIBUTE = 'Controller__REQUEST_NUMBER__' def filters = { logFilter(controller: '*', action: '*') { before = { if (!log.debugEnabled) return true long start = System.currentTimeMillis() long currentRequestNumber = REQUEST_NUMBER_COUNTER.incrementAndGet() request[START_TIME_ATTRIBUTE] = start request[REQUEST_NUMBER_ATTRIBUTE] = currentRequestNumber log.debug "preHandle request #$currentRequestNumber : " + "'$request.servletPath'/'$request.forwardURI', " + "from $request.remoteHost ($request.remoteAddr) " + " at ${new Date()}, Ajax: $request.xhr, controller: $controllerName, " + "action: $actionName, params: ${new TreeMap(params)}" return true } after = { Map model -> if (!log.debugEnabled) return true long start = request[START_TIME_ATTRIBUTE] long end = System.currentTimeMillis() long requestNumber = request[REQUEST_NUMBER_ATTRIBUTE] def msg = "postHandle request #$requestNumber: end ${new Date()}, " + "controller total time ${end - start}ms" if (log.traceEnabled) { log.trace msg + "; model: $model" } else { log.debug msg } } afterView = { Exception e -> if (!log.debugEnabled) return true long start = request[START_TIME_ATTRIBUTE] long end = System.currentTimeMillis() long requestNumber = request[REQUEST_NUMBER_ATTRIBUTE] def msg = "afterCompletion request #$requestNumber: " + "end ${new Date()}, total time ${end - start}ms" if (e) { log.debug "$msg \n\texception: $e.message", e } else { log.debug msg } } } } }
model map in the after filter is mutable. If you need to add or remove items from the model map you can do that in the after filter.
before- 在操作之前执行。返回值false表示响应已经被符合条件的过滤器处理过,并且其操作不被执行after- 在操作之后执行。其第一个参数为视图模型(view model),并且允许在渲染视图之前修改此模型afterView- 在渲染视图之后执行。如果有异常发生,其第一个参数为一个非null的异常。注意:此闭包在应用布局以前被调用。
class SecurityFilters {
def filters = {
loginCheck(controller: '*', action: '*') {
before = {
if (!session.user && !actionName.equals('login')) {
redirect(action: 'login')
return false
}
}
}
}
}loginCheck过滤器使用了before拦截器来执行一个代码块,用以检查一个用户是否在会话当中,如果不在,就重定向到login操作。注意:如何通过返回false的方式来确保操作本身不被执行。下面是一个更深入的示例来演示所有的三种过滤器类型:import java.util.concurrent.atomic.AtomicLongclass LoggingFilters { private static final AtomicLong REQUEST_NUMBER_COUNTER = new AtomicLong() private static final String START_TIME_ATTRIBUTE = 'Controller__START_TIME__' private static final String REQUEST_NUMBER_ATTRIBUTE = 'Controller__REQUEST_NUMBER__' def filters = { logFilter(controller: '*', action: '*') { before = { if (!log.debugEnabled) return true long start = System.currentTimeMillis() long currentRequestNumber = REQUEST_NUMBER_COUNTER.incrementAndGet() request[START_TIME_ATTRIBUTE] = start request[REQUEST_NUMBER_ATTRIBUTE] = currentRequestNumber log.debug "preHandle request #$currentRequestNumber : " + "'$request.servletPath'/'$request.forwardURI', " + "from $request.remoteHost ($request.remoteAddr) " + " at ${new Date()}, Ajax: $request.xhr, controller: $controllerName, " + "action: $actionName, params: ${new TreeMap(params)}" return true } after = { Map model -> if (!log.debugEnabled) return true long start = request[START_TIME_ATTRIBUTE] long end = System.currentTimeMillis() long requestNumber = request[REQUEST_NUMBER_ATTRIBUTE] def msg = "postHandle request #$requestNumber: end ${new Date()}, " + "controller total time ${end - start}ms" if (log.traceEnabled) { log.trace msg + "; model: $model" } else { log.debug msg } } afterView = { Exception e -> if (!log.debugEnabled) return true long start = request[START_TIME_ATTRIBUTE] long end = System.currentTimeMillis() long requestNumber = request[REQUEST_NUMBER_ATTRIBUTE] def msg = "afterCompletion request #$requestNumber: " + "end ${new Date()}, total time ${end - start}ms" if (e) { log.debug "$msg \n\texception: $e.message", e } else { log.debug msg } } } } }
after过滤器中的model是可变的。如果你需要增加或者移除model的内容,可以在after过滤器中实现。

