本节重点：
ActionChains 类
- context_click() 右击
- double_click() 双击
- drag_and_drop() 拖动
测试的产品中有一个操作是右键点击文件列表会弹出一个快捷菜单，可以方便的选择快捷菜单中的选择对文件进行操作（删除、移动、重命名），之前学习元素的点击非常简单：
driver.find_element_by_id(“xxx”).click()
那么鼠标的双击、右击、拖动等是否也是这样的写法呢？例如右击：
driver.find_element_by_id(“xxx”).context_click()
经过运行脚本得到了下面的错误提示：
AttributeError: 'WebElement' object has no attribute 'context_click'
提示右点方法不属于webelement 对象，通过查找文档，发现属于ActionChains 类，但文档中没有具体写法。这里要感谢 北京-QC-rabbit 的指点，其实整个python+selenium 学习过程都要感谢 北京-QC-rabbit 的指点。
下面介绍鼠标右键的用法，以快播私有云为例：
#coding=utf-8
from selenium import webdriver
from selenium.webdriver.common.action_chains import ActionChains
import time
driver = webdriver.Firefox()
driver.get("http://passport.kuaibo.com/login/?referrer=http%3A%2F%2Fwebcloud.kuaibo.com%2F")
#登陆快播私有云
driver.find_element_by_id("user_name").send_keys("username")
driver.find_element_by_id("user_pwd").send_keys("123456")
driver.find_element_by_id("dl_an_submit").click()
time.sleep(3)
#定位到要右击的元素
qqq =driver.find_element_by_xpath("/html/body/div/div[2]/div[2]/div/div[3]/table/tbody/tr/td[2]")
#对定位到的元素执行鼠标右键操作
ActionChains(driver).context_click(qqq).perform()
'''
#你也可以使用三行的写法，但我觉得上面两行写法更容易理解
chain = ActionChains(driver)
implement = driver.find_element_by_xpath("/html/body/div/div[2]/div[2]/div/div[3]/table/tbody/tr/td[2]")
chain.context_click(implement).perform()
'''
time.sleep(3) #休眠3秒
driver.close()
这里需要注意的是，在使用ActionChains 类之前，要先将包引入。
右击的操作会了，下面的其它方法比葫芦画瓢也能写出来。
鼠标双击的写法：
#定位到要双击的元素
qqq =driver.find_element_by_xpath("xxx")
#对定位到的元素执行鼠标双击操作
ActionChains(driver).double_click(qqq).perform()
鼠标拖放操作的写法：
#定位元素的原位置
element = driver.find_element_by_name("source")
#定位元素要移动到的目标位置
target = driver.find_element_by_name("target")
#执行元素的移动操作
ActionChains(driver).drag_and_drop(element, target).perform()
ActionChains 类不仅仅是只包含了上面的三个方法，下面将方法列出：
class ActionChains(driver)
driver:The WebDriver instance which performs user actions.
Generate user actions. All actions are stored in the ActionChains object. Call perform() to fire stored actions.
– perform()
Performs all stored actions.
– click(on_element=None)
Clicks an element.
on_element:The element to click. If None, clicks on current mouse position.
– click_and_hold(on_element)
Holds down the left mouse button on an element.
on_element:The element to mouse down. If None, clicks on current mouse position.
– context_click(on_element)
Performs a context-click (right click) on an element.
on_element:The element to context-click. If None, clicks on current mouse position.
– double_click(on_element)
Double-clicks an element.
on_element:The element to double-click. If None, clicks on current mouse position.
– drag_and_drop(source, target)
Holds down the left mouse button on the source element, then moves to the target element and releases the mouse button.
source:The element to mouse down.
target: The element to mouse up.
– key_down(key, element=None)
Sends a key press only, without releasing it. Should only be used with modifier keys (Control, Alt andShift).
key:The modifier key to send. Values are defined in Keys class.
element:The element to send keys. If None, sends a key to current focused element.
– key_up(key, element=None)
Releases a modifier key.
key:The modifier key to send. Values are defined in Keys class.
element:The element to send keys. If None, sends a key to current focused element.
– move_by_offset(xoffset, yoffset)
Moving the mouse to an offset from current mouse position.
xoffset:X offset to move to.yoffset:Y offset to move to.
– move_to_element(to_element)
Moving the mouse to the middle of an element.
to_element: The element to move to.
– move_to_element_with_offset(to_element, xoffset, yoffset)
Move the mouse by an offset of the specificed element. Offsets are relative to the top-left corner of the
element.
to_element: The element to move to.xoffset:X offset to move to.yoffset:Y offset to move to.
– release(on_element)
Releasing a held mouse button.
on_element:The element to mouse up.
– send_keys(*keys_to_send)
Sends keys to current focused element.
keys_to_send:The keys to send.
– send_keys_to_element(self, element,*keys_to_send):
Sends keys to an element.
element:The element to send keys.keys_to_send:The keys to send.
