事件处理机制为捕捉和处理网页整个生命周期中的事件提供了途径。以下简洁的程序记录了所有页面事件的顺序及其名称。
页面事件处理程序被包含在PageEventHandlers类中，分为三个不同的组别，以管理页面事件的各个阶段：
CrawlEventHandlers - 处理在爬取迭代中发生的事件。LoadEventHandlers - 管理与页面加载和解析相关的事件。BrowseEventHandlers - 控制交互式浏览阶段发生的事件，包括促使加载或显示相关元素的动作。
/**
* Print the call sequence and the event name of all page event handlers
* */
class PrintFlowEventHandlers: DefaultPageEventHandlers() {
private val sequencer = AtomicInteger()
private val seq get() = sequencer.incrementAndGet()
init {
loadEventHandlers.apply {
onNormalize.addLast { url ->
println("$seq. load - onNormalize")
url
}
onWillLoad.addLast { url ->
println("$seq. load - onWillLoad")
null
}
onWillFetch.addLast { page ->
println("$seq. load - onWillFetch")
}
onFetched.addLast { page ->
println("$seq. load - onFetched")
}
onWillParse.addLast { page ->
println("$seq. load - onWillParse")
}
onWillParseHTMLDocument.addLast { page ->
println("$seq. load - onWillParseHTMLDocument")
}
onHTMLDocumentParsed.addLast { page: WebPage, document: FeaturedDocument ->
println("$seq. load - onHTMLDocumentParsed")
}
onParsed.addLast { page ->
println("$seq. load - onParsed")
}
onLoaded.addLast { page ->
println("$seq. load - onLoaded")
}
}
browseEventHandlers.apply {
onWillLaunchBrowser.addLast { page ->
println("$seq. browse - onWillLaunchBrowser")
}
onBrowserLaunched.addLast { page, driver ->
println("$seq. browse - onBrowserLaunched")
}
onWillNavigate.addLast { page, driver ->
println("$seq. browse - onWillNavigate")
}
onNavigated.addLast { page, driver ->
println("$seq. browse - onNavigated")
}
onWillInteract.addLast { page, driver ->
println("$seq. browse - onWillInteract")
}
onWillCheckDocumentState.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onWillCheckDocumentState")
}
onDocumentActuallyReady.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onDocumentActuallyReady")
}
onWillScroll.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onWillScroll")
}
onDidScroll.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onDidScroll")
}
onDocumentSteady.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onDocumentSteady")
}
onWillComputeFeature.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onWillComputeFeature")
}
onFeatureComputed.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onFeatureComputed")
}
onDidInteract.addLast { page, driver ->
println("$seq. browse - onDidInteract")
}
onWillStopTab.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onWillStopTab")
}
onTabStopped.addLast { page: WebPage, driver: WebDriver ->
println("$seq. browse - onTabStopped")
}
}
crawlEventHandlers.apply {
onWillLoad.addLast { url: UrlAware ->
println("$seq. crawl - onWillLoad")
url
}
onLoaded.addLast { url, page ->
println("$seq. crawl - onLoaded")
}
}
}
}
以及调用入口：
/**
* Demonstrates how to use event handlers.
* */
fun main() {
BrowserSettings.withSystemDefaultBrowser()
val url = "https://www.amazon.com/dp/B0C1H26C46"
val session = PulsarContexts.createSession()
val link = ListenableHyperlink(url, args = "-refresh -parse", event = PrintFlowEventHandlers())
// submit the link to the fetch pool.
session.submit(link)
// wait until all done.
PulsarContexts.await()
}
该示例程序输出如下：
1. crawl - onWillLoad
2. load - onNormalize
3. load - onWillLoad
4. load - onWillFetch
5. browse - onWillLaunchBrowser
6. browse - onBrowserLaunched
7. browse - onWillNavigate
8. browse - onNavigated
9. browse - onWillNavigate
10. browse - onWillCheckDocumentState
11. browse - onDocumentActuallyReady
12. browse - onWillScroll
13. browse - onDidScroll
14. browse - onDocumentSteady
15. browse - onWillComputeFeature
16. browse - onFeatureComputed
17. browse - onDidInteract
18. browse - onWillStopTab
19. browse - onTabStopped
20. load - onFetched
21. load - onWillParse
22. load - onWillParseHTMLDocument
23. load - onHTMLDocumentParsed
24. load - onParsed
25. load - onLoaded
26. crawl - onLoaded