selenium - FindBy 属性何时触发 driver.FindElement？

Question

我的问题是:用 findby 属性装饰的 webelement 是否在每次引用它们时调用 findelement 函数？如果没有，什么时候？

List< webelement > 也被修饰的过程是什么？当您引用列表或引用该列表中的元素时，它会触发吗？

我之所以这么问是因为我在某些情况下会遇到过时的元素异常，我想知道如何处理它们。

Answer 1

WebElements 被懒惰地评估。也就是说，如果您从不使用 PageObject 中的 WebElement 字段，则永远不会为它调用“findElement”。 Reference .

如果不想WebDriver每次要查询元素，你必须使用@CacheLookup注解。

What about the list part of my question?

当您从列表中查询时会触发 findElements。说你有:

@FindBy(xpath = "//div[@class=\"langlist langlist-large\"]//a")
private List<WebElement> list;

以下代码示例全部触发器 findElements :

list.isEmpty();

WebElement element = list.get(0);
然而

List<WebElement> newList = new ArrayList<WebElement>();
newList = list;

不触发 findElements()。

请查看 LocatingElementListHandler类(class)。我建议深入研究来源以获得答案。

您可能会发现 PageFactory 类中的此代码注释很有帮助:

/**
   * Instantiate an instance of the given class, and set a lazy proxy for each of the WebElement
   * and List<WebElement> fields that have been declared, assuming that the field name is also
   * the HTML element's "id" or "name". This means that for the class:
   * 
   * <code>
   * public class Page {
   *     private WebElement submit;
   * }
   * </code>
   * 
   * there will be an element that can be located using the xpath expression "//*[@id='submit']" or
   * "//*[@name='submit']"
   * 
   * By default, the element or the list is looked up each and every time a method is called upon it.
   * To change this behaviour, simply annotate the field with the {@link CacheLookup}.
   * To change how the element is located, use the {@link FindBy} annotation.
   * 
   * This method will attempt to instantiate the class given to it, preferably using a constructor
   * which takes a WebDriver instance as its only argument or falling back on a no-arg constructor.
   * An exception will be thrown if the class cannot be instantiated.
   * 
   * @see FindBy
   * @see CacheLookup
   * @param driver The driver that will be used to look up the elements
   * @param pageClassToProxy A class which will be initialised.
   * @return An instantiated instance of the class with WebElement and List<WebElement> fields proxied
   */