java - Selenium 无法使用 xpath 定位元素，但 firebug 可以

Question

我有以下代码来使用 Xpath 来定位元素，使用 Firebug 效果很好。当我运行程序时，出现以下异常:

Exception in thread "main" org.openqa.selenium.NoSuchElementException: Unable to locate element: {"method":"xpath","selector":"(//div[@class=\" x-ignore x-menu x-component \"]//div)/a[text()=\"ID\"]"}

如果我采用确切的 xpath 并坚持使用 Firebug，我可以发现我的元素没有问题。为什么 Selenium 找不到它，有什么想法吗？

这是我的代码:

public static void displayColumn(String column) throws Exception {
    String columnOptionsDropdownXpath = "(//div[@class=\"x-grid3-header\"]//span)[1]/../a";
    String columnXpath = "(//div[@class=\"x-grid3-header\"]//span)[1]";
    String columnsXpath = "(//div[@class=\" x-ignore x-menu x-component\"]//a)[3]";
    String columnToDisplayXpath = "(//div[@class=\" x-ignore x-menu x-component \"]//div)/a[text()=\"" + column + "\"]";

    // Because the 'column options' button doesn't appear until you hover over the column
    WebElement col = null;
    try {
        col = driver.findElement(By.xpath(columnXpath));
    } catch (NoSuchElementException e) {
        System.out.println("Column not found - is it displayed?");
    }

    Actions builder = new Actions(driver);
    builder.moveToElement(col).build().perform();
    WebElement element = driver.findElement(By.xpath(columnOptionsDropdownXpath));
    element.click();
    Thread.sleep(500);

    element = driver.findElement(By.xpath(columnsXpath));
    builder.moveToElement(element).build().perform();
    Thread.sleep(2000);
    WebDriverWait wait = new WebDriverWait(driver, 10);
    try {
        System.out.println("in try statement");
        wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath(columnToDisplayXpath)));
    } catch (TimeoutException e) {}

    element = driver.findElement(By.xpath(columnToDisplayXpath));
    element.click();
}

Answer 1

正如评论中提到的，这两个 XPath 之间的细微差别:

String columnsXpath = "(//div[@class=\" x-ignore x-menu x-component\"]//a)[3]";
String columnToDisplayXpath = "(//div[@class=\" x-ignore x-menu x-component \"]//div)/a[text()=\"" + column + "\"]";

除了最后的部分之外，就是后者“组件”后面有一个空格，而前者没有。

我怀疑使用 normalize-space() 并删除比较值中的前导和尾随空格可能有助于消除 @class 属性值间距的不一致:

String columnsXpath = "(//div[normalize-space(@class) = \"x-ignore x-menu x-component\"]//a)[3]";
String columnToDisplayXpath = 
    "(//div[normalize-space(@class) = \"x-ignore x-menu x-component\"]//div)/a[text()=\""
    + column + "\"]";