Xitrum学习笔记15

Before过滤器

Before过滤器在action执行之前执行。如果before过滤器响应返回了什么内容，在它之后的所有过滤器和action都不再运行

import xitrum.Action
import xitrum.annotation.GET
@GET("before_filter")
class MyAction extends Action {
  beforeFilter {
    log.info("I run therefore I am")
  }
  // This method is run after the above filters
  def execute() {
    respondInlineView("Before filters should have been run, please check the log")
  }
}

After过滤器

After过滤器在action运行之后运行，是不带参数的函数，返回值会被忽略

import xitrum.Action
import xitrum.annotation.GET
@GET("after_filter")
class MyAction extends Action {
  afterFilter {
    log.info("Run at " + System.currentTimeMillis())
  }
  def execute() {
    respondText("After filter should have been run, please check the log")
  }
}

Around过滤器

import xitrum.Action
import xitrum.annotation.GET
@GET("around_filter")
class MyAction extends Action {
  aroundFilter { action =>
    val begin = System.currentTimeMillis()
    action()
    val end = System.currentTimeMillis()
    val dt = end - begin
    log.info(s"The action took $dt [ms]")
  }
  def execute() {
    respondText("Around filter should have been run, please check the log")
  }
}

如果有多个around过滤器，它们会被嵌套使用。

过滤器的执行顺序

Before过滤器先被执行，然后是around过滤器，最后是after过滤器
如果before过滤器中的一个返回false，其他的过滤器（包括around和after）将不再执行
After过滤器会在至少一个around过滤器被执行后执行
如果一个around过滤器不调用action()，内嵌的around过滤器将不会执行