以東方財富網登入頁面為例：

在查詢元素過程中，直接通過id或者xpath等找不到元素，檢視頁面原始碼發現元素是屬於iframe裡，例如：

<div class="wrap_login">
        <iframe class="frame_login" src="https://exaccount.eastmoney.com/home/login?request=%7b%22agentPageUrl%22%3a%22https%3a%2f%2fpassport.eastmoney.com%2fpub%2fLoginAgent%22%2c%22redirectUrl%22%3a%22http%3a%2f%2fwww.eastmoney.com%2f%22%2c%22callBack%22%3a%22LoginCallBack%22%2c%22redirectFunc%22%3a%22PageRedirect%22%2c%22data%22%3a%7b%22domainName%22%3a%22passport.eastmoney.com%22%2c%22deviceType%22%3a%22Web%22%2c%22productType%22%3a%22UserPassport%22%2c%22versionId%22%3a%220.0.1%22%7d%7d"></iframe>
    </div>

以下為了定位到iframe裡面元素，有2種方法：

方法一：單獨開啟iframe網址，直接定位。

    @Test
    public void loginTest() throws InterruptedException {

        System.setProperty("webdriver.firefox.bin", "D:\\Program Files\\Mozilla Firefox\\firefox.exe");
        WebDriver driver = new FirefoxDriver();
        driver.get("https://exaccount.eastmoney.com/home/login?request=%7b%22agentPageUrl%22%3a%22https%3a%2f%2fpassport.eastmoney.com%2fpub%2fLoginAgent%22%2c%22redirectUrl%22%3a%22http%3a%2f%2fwww.eastmoney.com%2f%22%2c%22callBack%22%3a%22LoginCallBack%22%2c%22redirectFunc%22%3a%22PageRedirect%22%2c%22data%22%3a%7b%22domainName%22%3a%22passport.eastmoney.com%22%2c%22deviceType%22%3a%22Web%22%2c%22productType%22%3a%22UserPassport%22%2c%22versionId%22%3a%220.0.1%22%7d%7d");  
        driver.manage().window().maximize();
        Thread.sleep(3000);   
        driver.findElement(By.id("txt_account")).sendKeys("ycyzharry");
        driver.findElement(By.id("txt_pwd")).sendKeys("password");
        driver.findElement(By.id("btn_login")).click();
    }

}

方法二：先切換到iframe，再進行定位。

    @Test
    public void clickButtonTest() throws InterruptedException {

        System.setProperty("webdriver.firefox.bin", "D:\\Program Files\\Mozilla Firefox\\firefox.exe");
        WebDriver driver = new FirefoxDriver();
        driver.get("https://passport.eastmoney.com/pub/login?backurl=http%3A//www.eastmoney.com/");
        driver.manage().window().maximize();
        Thread.sleep(3000);

        WebElement iframe = driver.findElement(By.className("frame_login"));
        driver.switchTo().frame(iframe);
        driver.findElement(By.id("txt_account")).sendKeys("ycyzharry");
        driver.findElement(By.id("txt_pwd")).sendKeys("password");
        driver.findElement(By.id("btn_login")).click();

   }

}

值得注意的是，如果iframe有id時，切換iframe時把id作為引數直接傳入

driver.switchTo().frame("id");

以上示例中，iframe沒有id，只有class="frame_login"，所以我們需要先通過classname定位到iframe元素，再把該元素作為引數傳入。

例如，如果要跳出iframe，可以使用以下方法：

driver.switchTo().defaultContent();