Selenium Marionette getLocation nullpointer

Question

我遇到了：

Exception in thread "main" java.lang.NullPointerException at org.openqa.selenium.remote.RemoteWebElement.getLocation(RemoteWebElement.java:338)

尝试在https://signup.live.com/获取验证码的BufferedImage：

public BufferedImage getCaptchaBufferedImage() throws IOException, InterruptedException {
  System.out.println("Looking for captcha image");

  this.wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("hipTemplateContainer")));
  System.out.println("Found image");

  WebElement element = this.driver.findElement(By.id("hipTemplateContainer"));
  System.out.println(element.getAttribute("outerHTML"));
  List<WebElement> childs = element.findElements(By.xpath(".//*"));
  WebElement firstChild = childs.get(0);
  System.out.println(firstChild.getAttribute("outerHTML"));
  List<WebElement> childs2 = firstChild.findElements(By.xpath(".//*"));
  WebElement imageChild = childs2.get(0);
  System.out.println(imageChild.getAttribute("outerHTML"));
  ((JavascriptExecutor) this.driver).executeScript("arguments[0].scrollIntoView(true);", imageChild);
  String id = imageChild.getAttribute("id");
  this.wait.until(ExpectedConditions.visibilityOfElementLocated(By.id(id)));
  **Point point = firstChild.getLocation();**

  byte[] img_bytes = ((TakesScreenshot) this.driver).getScreenshotAs(OutputType.BYTES);
  BufferedImage imageScreen = ImageIO.read(new ByteArrayInputStream(img_bytes));
  System.out.println("Downloaded image");

  double d = Double.parseDouble(firstChild.getCssValue("height").split("px")[0]);
  int height = (int) d;
  double e = Double.parseDouble(firstChild.getCssValue("width").split("px")[0]);
  int width = (int) e;

  BufferedImage captcha = imageScreen.getSubimage(point.getX(), point.getY(), width, height);
  JFrame frame = new JFrame();
  frame.getContentPane().setLayout(new FlowLayout());
  frame.getContentPane().add(new JLabel(new ImageIcon(captcha)));
  frame.pack();
  frame.setVisible(true);
  return captcha;
}

我在网上看了一遍，无法解决这个问题.Selenium 3.0可能存在错误？如果我跳过获取图像的偏移量并且只是对getSubImage（）中的值进行硬编码，则此代码有效。

Answer 1

我试了两个多小时才猜到了什么？我发现了这个问题。

<强>问题： 这是因为getScreenshotAs仅占用页面的可见部分（在滚动到验证码之后）但没有完成页面，因此导致所有问题。它导致Point返回的Y坐标（1041）相对于complete网页，但截图图像具有不同的Y坐标，用于验证码（300）相对到部分页面。因此导致以下例外：

java.awt.image.RasterFormatException: (y + height) is outside of Raster

  

X坐标在完整网页和部分中都是相同的值   网页。

所以，将Y坐标硬编码为300解决了临时问题。 BUt实际问题是为什么没有为完整页面而不是jus可见页面截取屏幕截图。可能是最新的geckodriver（firefox驱动程序）中的错误。在Firefox 49 version with Selenium 3 version, geckodriver v0.1.11 and Java 1.8尝试过。

以下是代码。请尝试告诉我：

    driver.get("https://signup.live.com/");
    driver.manage().window().maximize();

    System.out.println("Looking for captcha image");
    WebDriverWait wait = new WebDriverWait(driver, 10);
    wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("hipTemplateContainer")));
    System.out.println("Found image");

    WebElement element = driver.findElement(By.id("hipTemplateContainer"));
    System.out.println(element.getAttribute("outerHTML"));
    List<WebElement> childs = element.findElements(By.xpath(".//*"));
    WebElement firstChild = childs.get(0);
    System.out.println(firstChild.getAttribute("outerHTML"));
    List<WebElement> childs2 = firstChild.findElements(By.xpath(".//*"));
    WebElement imageChild = childs2.get(0);
    System.out.println(imageChild.getAttribute("outerHTML"));
    ((JavascriptExecutor) driver).executeScript("arguments[0].scrollIntoView(true);", imageChild);
    String id = imageChild.getAttribute("id");
    wait.until(ExpectedConditions.visibilityOfElementLocated(By.id(id)));

    Point point = imageChild.getLocation();

    int width = imageChild.getSize().getWidth();
    int height = imageChild.getSize().getHeight();

    System.out.println("height: " + height + "\t weight : " + width);
    System.out.println("X co-ordinate: " + point.getX());
    System.out.println("Y co-ordinate: " + point.getY());

    File screenshot = ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);

    FileUtils.copyFile(screenshot, new File("G:\\naveen\\screenshot.png"));
    BufferedImage imageScreen = ImageIO.read(screenshot);
    System.out.println("Downloaded image");

    BufferedImage captcha = imageScreen.getSubimage(245, 300, width, height);

    ImageIO.write(captcha, "png", screenshot);
    FileUtils.copyFile(screenshot, new File("G:\\naveen\\screenshot1.png"));

    JFrame frame = new JFrame();
    frame.getContentPane().setLayout(new FlowLayout());
    frame.getContentPane().add(new JLabel(new ImageIcon(captcha)));
    frame.pack();
    frame.setVisible(true);

以下是保存的屏幕截图：

1. 仅保存可见网页。



1. 子图像 - 验证码图片：