SeleniumWaiter:

import com.google.common.base.Function;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.ui.WebDriverWait;

public class SeleniumWaiter {

      private WebDriver driver;

      public SeleniumWaiter(WebDriver driver) {
           this.driver = driver;
      }

      public WebElement waitForMe(By locatorname, int timeout){
           WebDriverWait wait = new WebDriverWait(driver, timeout);
           return wait.until(SeleniumWaiter.presenceOfElementLocated(locatorname));
      }

      public static Function<WebDriver, WebElement> presenceOfElementLocated(final By locator) {
            // TODO Auto-generated method stub
            return new Function<WebDriver, WebElement>() {
                 @Override
                 public WebElement apply(WebDriver driver) {
                      return driver.findElement(locator);
                 }
            };
      }
 }

对你来说:

_waiter = new SeleniumWaiter(_driver);

try {
   _waiter.waitForMe(By.xpath("//..."), 10);
} 
catch (Exception e) {
   // Error
}

一般来说，使用Selenium 2.0时，web驱动程序应该只在确定页面已加载后才将控制权返回给调用代码。如果没有，您可以调用waitforeleement，它循环调用findelement，直到找到它或超时(可以设置超时)。

您可以尝试这段代码，让页面完全加载，直到找到元素为止。

public void waitForBrowserToLoadCompletely() {
    String state = null;
    String oldstate = null;
    try {
        System.out.print("Waiting for browser loading to complete");

        int i = 0;
        while (i < 5) {
            Thread.sleep(1000);
            state = ((JavascriptExecutor) driver).executeScript("return document.readyState;").toString();
            System.out.print("." + Character.toUpperCase(state.charAt(0)) + ".");
            if (state.equals("interactive") || state.equals("loading"))
                break;
            /*
             * If browser in 'complete' state since last X seconds. Return.
             */

            if (i == 1 && state.equals("complete")) {
                System.out.println();
                return;
            }
            i++;
        }
        i = 0;
        oldstate = null;
        Thread.sleep(2000);

        /*
         * Now wait for state to become complete
         */
        while (true) {
            state = ((JavascriptExecutor) driver).executeScript("return document.readyState;").toString();
            System.out.print("." + state.charAt(0) + ".");
            if (state.equals("complete"))
                break;

            if (state.equals(oldstate))
                i++;
            else
                i = 0;
            /*
             * If browser state is same (loading/interactive) since last 60
             * secs. Refresh the page.
             */
            if (i == 15 && state.equals("loading")) {
                System.out.println("\nBrowser in " + state + " state since last 60 secs. So refreshing browser.");
                driver.navigate().refresh();
                System.out.print("Waiting for browser loading to complete");
                i = 0;
            } else if (i == 6 && state.equals("interactive")) {
                System.out.println(
                        "\nBrowser in " + state + " state since last 30 secs. So starting with execution.");
                return;
            }

            Thread.sleep(4000);
            oldstate = state;

        }
        System.out.println();

    } catch (InterruptedException ie) {
        ie.printStackTrace();
    }
}

如果你想等待一个特定的元素加载，你可以在RenderedWebElement上使用isdisplay()方法:

// Sleep until the div we want is visible or 5 seconds is over
long end = System.currentTimeMillis() + 5000;
while (System.currentTimeMillis() < end) {
    // Browsers which render content (such as Firefox and IE) return "RenderedWebElements"
    RenderedWebElement resultsDiv = (RenderedWebElement) driver.findElement(By.className("gac_m"));

    // If results have been returned, the results are displayed in a drop down.
    if (resultsDiv.isDisplayed()) {
      break;
    }
}

(例子来自《5分钟入门指南》)

这似乎是WebDriver的一个严重限制。显然，等待一个元素并不意味着页面正在加载，特别是DOM可以完全构建(onready状态)，此时JS仍在执行，CSS和图像仍在加载。

我相信最简单的解决方案是在onload事件上设置一个JS变量，在所有东西初始化后，在Selenium中检查和等待这个JS变量。

隐式和显式的等待更好。

但是如果你在Java中处理一个异常，那么你可以使用这个来等待页面重新加载:

Thead.sleep(1000);