如何返回一个延迟实例化的动态webelement [英] How to return a lazily-instantiated dynamic webelement

问题描述

我一直在使用 @FindBy 一段时间了，我喜欢这个元素直到必要时才会找到（不是实例化）。

I've been using @FindBy for a while now, and I love the fact that the element doesn't get located until its necessary (not on instantiation).

但是，网页可能有2-10个特定元素，并且元素上的id已编号（因此第一个元素的id为element1 等等）

However, the webpage may have anywhere from 2-10 of a certain element, and the id's on the elements are numbered (so the first element has an id of "element1" and so forth)

我想编写一个函数，我可以传入一个整数，它将返回一个具有相应ID的WebElement， AND 懒惰地实例化。这意味着具有以下功能将无效：

I would like to write a function where I can pass in an integer, and it will return a WebElement with the appropriate ID, AND is lazily instantiated. That means having a function like the following won't work:

public WebElement getElement(int numOnPage){
    return driver.findElement(By.id("element"+numOnPage));
}

因为我调用该函数的瞬间WebElement就位。 （它无法实例化的原因是因为我有一个函数，通过一遍又一遍地调用isDisplayed（）来等待元素存在，捕获 NoSuchElementException s ）。

Because the instant I call that function the WebElement gets located. (The reason why it can't be instantiated is because I have a function that waits until it the element exists by calling isDisplayed() over and over on it, catching NoSuchElementExceptions).

我也意识到我可以创建一个 List< WebElement> ，它通过CSS选择每个ID的元素以element开头，但我还有其他情况需要返回动态生成的元素，并且还必须在那里使用解决方法。

I also realize that I could create a List<WebElement> that selects via CSS every element whose ID starts with "element" but I have had other cases where I've wanted to return a dynamically generated element, and had to use a workaround there as well.

谢谢！

推荐答案

首先，我真的不明白为什么你绝对需要一个 WebElement 元素真正在页面之前的引用。在正常情况下，您可以检查页面是否已完全加载，然后查找 WebElement 。首先通常会使用循环和 NoSuchElementException 的捕获来完成。

First, I don't really understand why you absolutely need to get a WebElement reference before the element is really in the page. In a normal case, you could check that the page is completely loaded and then find for a WebElement. First would be typically done with a loop and a catch for NoSuchElementException as you mentioned.

但是，如果需要在页面中找不到 WebElement 的引用之前，我只想创建一个懒惰加载的代理（仅在第一次需要时）真正的 WebElement 实例。这样的事情：

However, if you need a reference for a WebElement before it can't be found in the page, I would simply create a proxy which loads lazily (only when first time needed) the real WebElement instance. Something like this:

public WebElement getElement(final int numOnPage) {
        return (WebElement) Proxy.newProxyInstance(this.getClass().getClassLoader(), new Class<?>[] { WebElement.class }, new InvocationHandler() {
            // Lazy initialized instance of WebElement
            private WebElement webElement;

            public Object invoke(Object proxy, Method method, Object[] args)
                    throws Throwable {
                if (webElement == null) {
                    webElement = driver.findElement(By.id("element" + numOnPage));
                }
                return method.invoke(webElement, args);
            }
        });
    }

通过调用 getElement ，您检索 WebElement 类型的对象。只要您调用其中一个方法，就会使用 WebDriver.findElement 检索它。请注意，如果您在代理实例上调用方法，则该元素必须位于页面中，否则您将获得 NoSuchElementException 。

By calling getElement, you retrieve an object of type WebElement. As soon as you call one of its method, it will be retrieved using WebDriver.findElement. Note that, if you call a method on the proxy instance, the element must be in the page otherwise you get of course a NoSuchElementException.

这篇关于如何返回一个延迟实例化的动态webelement的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！