switch窗口句柄

         Set<String>  windows = browser.getWebDriver().getWindowHandles();  //获得所有窗口句柄
         for (String string : windows) {
             System.out.println(string);                                    //打印所有窗口句柄
         }
         String currWin = browser.getWebDriver().getWindowHandle();
         System.out.println(currWin);
         Iterator<String> it = windows.iterator();
         while(it.hasNext()) {
             String handle = it.next();
             if(currWin.equals(handle))
                 continue;
             browser.getWebDriver().switchTo().window(handle);               //切换窗口
         }

         browser.pause(5);

         String Win2 = browser.getWebDriver().getWindowHandle();
         System.out.println(Win2);                                           //再次打印当前窗口句柄,与currWin不一样