WebDriver啟動的時候很容易無限掛起，直到外圍框架設定的超時時間達到而退出執行，給測試執行帶來很大的困擾。上一篇文件WebDriver啟動時白屏掛起問題解決方法（一）給出的解決方案只是能夠部分地解決工具問題，但有時候這種hang死會發生在timeouts().pageLoadTimeout()發生作用之前。也就是說，這需要更為徹底的方法去解決這個問題，我想到最簡單的方式是用獨立的守護執行緒去看守，具體程式碼如下：

	private final int DRIVER_STATUS_TEST_TIMES = 2;
	private final int DRIVER_START_TIMEOUT = 30000;

	/**
	 * Description: start webdirver</BR>
	 * 內容描述：啟動WebDriver例項。
	 * 
	 * @param browserMode the browser mode
	 */
	private void startWebDriver(String browserMode){
		try {
			setBuildEnvChoice(browserMode);
			initalizeWebDriver(DRIVER_START_TIMEOUT);
			
			//the address "about:blank" is sometimes useless.
			ensureWebDriverStatus(browserMode, getServerAddress(), DRIVER_STATUS_TEST_TIMES);
			
			setPageLoadTimeout(maxLoadTime);
			setElementLocateTimeout(maxWaitfor);
			setScriptingTimeout(maxWaitfor);
			
			actionDriver = new Actions(driver);
			ASSERT = new StarNewAssertion(driver, LOG_ABS, className, logger, devidor);
			pass("webdriver new instance created");	
		} catch (Exception e) {
			LOG.error(e);
			throw new RuntimeException(e);
		}		
	}

	/**
	 * Description: start webdirver using browser iexplore</BR>
	 * 內容描述：預設選擇IE模式建立WebDriver例項。
	 */
	protected void startWebDriver() {
		startWebDriver("ie");
	}

	/**
	 * Description: start webdirver after capabilities settings completed.</BR>
	 * 內容描述：在做好配置之後建立WebDriver例項。
	 */
	private void initalizeWebDriver() {
		WebDriverListener listener = new WebDriverListener(LOG_ABS, className, logger, devidor);
		if (USE_DRIVERSERVER) {// 是否使用IEDirverServer
			driver = new EventFiringWebDriver(new RemoteWebDriver(service.getUrl(), capabilities)).register(listener);
		} else {
			try {
				URL url = new URL("http://localhost:" + server.getPort() + "/wd/hub");
				driver = new EventFiringWebDriver(new RemoteWebDriver(url, capabilities)).register(listener);
			} catch (MalformedURLException e) {
				throw new RuntimeException("illegal url!");				
			}
		}
	}
	
	/**
	 * Description: start and see if webdirver start successfully.</BR>
	 * 內容描述：建立並且判斷WebDriver例項是否啟動成功。
	 * 
	 * @param timeout timeout for start webdriver.
	 * @param redoCount retry times for start webdriver.
	 * @throws Exception
	 */
	private void initalizeWebDriver(long timeout, int redoCount) throws Exception {
		for (int i = 0; i < redoCount; i++) {
			Thread thread_start = new Thread(new Runnable() {
				public void run() {// 用一個獨立的執行緒啟動WebDriver
					initalizeWebDriver();
				}
			});
			thread_start.start();
			waitFor(thread_start, timeout);//為啟動WebDriver設定超時時間
			if (!thread_start.isAlive()) {
				return;
			} else {
				thread_start.interrupt();
				consoleError("start Webdriver failed 【" + i + "】 times!");
			}
			if (thread_start.isAlive() && i == redoCount){// 如果最終沒能啟動成功則丟擲錯誤
				thread_start.interrupt();
				throw new RuntimeException("can not start webdriver, check your platform configurations!");
			}
		}
	}