Java 使用Selenium选择XPath按钮时出现InvalidSelectorException

我构建了一个类来验证tweet是否提交到Twitter。每当我试图点击submit按钮时，就会收到一个InvalidSelectorException。它似乎有一个非常合理的xpath，采用xpath=//button[@type='button'][17]的形式，所以我不确定它在抱怨什么。有一只雄鸡：

public class ValidationTest {
    private WebDriver driver;
    private String baseUrl;
    private StringBuffer verificationErrors = new StringBuffer();

    @Before
    public void setUp() throws Exception {

        // Google Chrome
        File file = new File("C:\\Users\\User\\plugins\\Twitter\\src\\chromedriver.exe");
        System.setProperty("webdriver.chrome.driver", file.getAbsolutePath());
        driver = new ChromeDriver();

        // Firefox
        // driver = new FirefoxDriver();

        baseUrl = "https://www.twitter.com";
        driver.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);
    }

    @Test
    public void testValidation() throws Exception {

        // Authentication information
        String username = "user123";
        String password = "pass123";

        // Open site
        launchActivity("/");

        // Maximize window
        maximizeWindow();

        // Enter authentication information
        sendKeysAndWait("signin-email", username);
        sendKeysAndWait("signin-password", password);

        // Log in
        clickXPathButtonAndWait("//button[@type='submit']");

        // Parses a text file to produce an ArrayList from which short (140
        // char) messages may be sent
        parseStory();

    }

    /**
     * 
     * @param extension
     *            The remainder of the URL, after baseUrl
     */
    private void launchActivity(String extension) {
        driver.get(baseUrl + extension);
    }

    private void maximizeWindow() throws InterruptedException {
        driver.manage().window().maximize();
        sleepShort();
    }

    /**
     * s Writes a string to an HTML element and waits a random time
     * 
     * @param elem
     *            The element to send the keys
     * @param keys
     *            The string to write to the element
     * @throws InterruptedException
     */
    private void sendKeysAndWait(String elem, String keys) throws InterruptedException {
        driver.findElement(By.id(elem)).click();
        driver.findElement(By.id(elem)).sendKeys(keys);
        sleepShort();
    }

    /**
     * 
     * @param id
     *            The id of the button found in HTML
     * @throws InterruptedException
     */
    private void clickButtonAndWait(String id) throws InterruptedException {
        driver.findElement(By.id(id)).click();
        sleepShort();
    }

    @SuppressWarnings("unused")
    private void clickCSSButtonAndWait(String id) throws InterruptedException {
        driver.findElement(By.cssSelector(id)).click();
        sleepShort();
    }

    private void clickXPathButtonAndWait(String id) throws InterruptedException {
        driver.findElement(By.xpath(id)).click();
        sleepShort();
    }

    private void parseStory() throws FileNotFoundException, IOException, InterruptedException {
        FileInputStream fstream = new FileInputStream("C:\\Users\\User\\workspace\\Twitter\\src\\text.txt");
        BufferedReader br = new BufferedReader(new InputStreamReader(fstream));
        String strLine;

        List<String> list = new ArrayList<String>();

        // Read the text file line by line
        while ((strLine = br.readLine()) != null) {

            // Create ArrayList to store text in 140 character chunks
            while ((strLine = br.readLine()) != null) {
                if (!strLine.isEmpty()) {
                    list.add(strLine);
                    String[] stringArr = strLine.split("(?<=\\G.{140})");
                    System.out.println(Arrays.toString(stringArr));

                    // Send 1.5 messages per minute (40 messages per hour) for a
                    // total of 960 per day
                    for (String s : stringArr) {
                        clickButtonAndWait("tweet-box-home-timeline");
                        sendKeysAndWait("tweet-box-home-timeline", s);

                        //TODO The result is not a node set. and therefore cannot be converted to the desired type.
                        clickXPathButtonAndWait("xpath=(//button[@type='button'])[17]");
                        sleepLong();
                    }

                    System.out.println("All messages have been sent.");
                }
            }
        }

        // Close the input stream
        br.close();
    }

    private void sleepLong() throws InterruptedException {
        int randomWaitDuration = 75000 + (int) (Math.random() * 105000);
        Thread.sleep(randomWaitDuration);
    }

    private void sleepShort() throws InterruptedException {
        int randomWaitDuration = 500 + (int) (Math.random() * 1000);
        Thread.sleep(randomWaitDuration);
    }

    @After
    public void tearDown() throws Exception {
        driver.quit();
        String verificationErrorString = verificationErrors.toString();
        if (!"".equals(verificationErrorString)) {
            fail(verificationErrorString);
        }
    }
}

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发生此异常是由于xpath表达式无效

"xpath=(//button[@type='button'])[17]"   

作为参数传递给ClickXPathButton和Wait方法

试试这个

 clickXPathButtonAndWait("//button[@type='button']")

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正如您第一次登录时使用的那样。

//button[@type='button']是一个非常合理的xpath，但不是xpath=//button[@type='button'][17]您尝试了什么，结果如何？强烈反对张贴所有代码并说“看一看”。请阅读有关如何提问的帮助主题。您需要研究自己的问题，找到代码示例等，并编写自己的代码来解决问题。如果你做了所有这些，但仍然无法理解，那么回来编辑你的问题，并添加你所做研究的注释，你尝试过的代码缩减为a，以及结果是什么。。。任何错误消息等。包括任何相关的HTML并正确格式化HTML和代码也是非常重要的。谢谢。有时候，需要一双新的眼睛才能看到显而易见的东西。

 clickXPathButtonAndWait("//button[@type='button']")