上一篇博文簡(jiǎn)要

在上一篇博文中已得知：使用 execute 向遠(yuǎn)程服務(wù)器發(fā)送請(qǐng)求會(huì)通過(guò) webdriver 與瀏覽器交互，且發(fā)送已定義的命令常量可獲得一些相關(guān)信息。

其中 execute 方法實(shí)現(xiàn)已經(jīng)在上一篇博文中有實(shí)現(xiàn)說(shuō)明。并且在我們已經(jīng)知道 webdriver基類（selenium.webdriver.remote.webdriver）中，實(shí)現(xiàn)了操作頁(yè)面元素的基本方法。

通過(guò)簡(jiǎn)單運(yùn)用全面學(xué)習(xí)

假設(shè)現(xiàn)在需要打開百度，搜索“CSDN A757291228”該如何進(jìn)行操作呢?
通過(guò)查找 webdriver基類（selenium.webdriver.remote.webdriver）找到了以下幾個(gè)查找元素的方法：

def find_element_by_id(self, id_):"""Finds an element by id.:Args:- id\_ - The id of the element to be found.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_id('foo')"""return self.find_element(by=By.ID, value=id_)def find_elements_by_id(self, id_):"""Finds multiple elements by id.:Args:- id\_ - The id of the elements to be found.:Returns:- list of WebElement - a list with elements if any was found. Anempty list if not:Usage:elements = driver.find_elements_by_id('foo')"""return self.find_elements(by=By.ID, value=id_)def find_element_by_xpath(self, xpath):"""Finds an element by xpath.:Args:- xpath - The xpath locator of the element to find.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_xpath('//div/td[1]')"""return self.find_element(by=By.XPATH, value=xpath)def find_elements_by_xpath(self, xpath):"""Finds multiple elements by xpath.:Args:- xpath - The xpath locator of the elements to be found.:Returns:- list of WebElement - a list with elements if any was found. Anempty list if not:Usage:elements = driver.find_elements_by_xpath("//div[contains(@class, 'foo')]")"""return self.find_elements(by=By.XPATH, value=xpath)def find_element_by_link_text(self, link_text):"""Finds an element by link text.:Args:- link_text: The text of the element to be found.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_link_text('Sign In')"""return self.find_element(by=By.LINK_TEXT, value=link_text)def find_elements_by_link_text(self, text):"""Finds elements by link text.:Args:- link_text: The text of the elements to be found.:Returns:- list of webelement - a list with elements if any was found. anempty list if not:Usage:elements = driver.find_elements_by_link_text('Sign In')"""return self.find_elements(by=By.LINK_TEXT, value=text)def find_element_by_partial_link_text(self, link_text):"""Finds an element by a partial match of its link text.:Args:- link_text: The text of the element to partially match on.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_partial_link_text('Sign')"""return self.find_element(by=By.PARTIAL_LINK_TEXT, value=link_text)def find_elements_by_partial_link_text(self, link_text):"""Finds elements by a partial match of their link text.:Args:- link_text: The text of the element to partial match on.:Returns:- list of webelement - a list with elements if any was found. anempty list if not:Usage:elements = driver.find_elements_by_partial_link_text('Sign')"""return self.find_elements(by=By.PARTIAL_LINK_TEXT, value=link_text)def find_element_by_name(self, name):"""Finds an element by name.:Args:- name: The name of the element to find.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_name('foo')"""return self.find_element(by=By.NAME, value=name)def find_elements_by_name(self, name):"""Finds elements by name.:Args:- name: The name of the elements to find.:Returns:- list of webelement - a list with elements if any was found. anempty list if not:Usage:elements = driver.find_elements_by_name('foo')"""return self.find_elements(by=By.NAME, value=name)def find_element_by_tag_name(self, name):"""Finds an element by tag name.:Args:- name - name of html tag (eg: h1, a, span):Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_tag_name('h1')"""return self.find_element(by=By.TAG_NAME, value=name)def find_elements_by_tag_name(self, name):"""Finds elements by tag name.:Args:- name - name of html tag (eg: h1, a, span):Returns:- list of WebElement - a list with elements if any was found. Anempty list if not:Usage:elements = driver.find_elements_by_tag_name('h1')"""return self.find_elements(by=By.TAG_NAME, value=name)def find_element_by_class_name(self, name):"""Finds an element by class name.:Args:- name: The class name of the element to find.:Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_class_name('foo')"""return self.find_element(by=By.CLASS_NAME, value=name)def find_elements_by_class_name(self, name):"""Finds elements by class name.:Args:- name: The class name of the elements to find.:Returns:- list of WebElement - a list with elements if any was found. Anempty list if not:Usage:elements = driver.find_elements_by_class_name('foo')"""return self.find_elements(by=By.CLASS_NAME, value=name)def find_element_by_css_selector(self, css_selector):"""Finds an element by css selector.:Args:- css_selector - CSS selector string, ex: 'a.nav#home':Returns:- WebElement - the element if it was found:Raises:- NoSuchElementException - if the element wasn't found:Usage:element = driver.find_element_by_css_selector('#foo')"""return self.find_element(by=By.CSS_SELECTOR, value=css_selector)def find_elements_by_css_selector(self, css_selector):"""Finds elements by css selector.:Args:- css_selector - CSS selector string, ex: 'a.nav#home':Returns:- list of WebElement - a list with elements if any was found. Anempty list if not:Usage:elements = driver.find_elements_by_css_selector('.foo')"""return self.find_elements(by=By.CSS_SELECTOR, value=css_selector) def find_element(self, by=By.ID, value=None):"""Find an element given a By strategy and locator. Prefer the find_element_by_* methods whenpossible.:Usage:element = driver.find_element(By.ID, 'foo'):rtype: WebElement"""if self.w3c:if by == By.ID:by = By.CSS_SELECTORvalue = '[id="%s"]' % valueelif by == By.TAG_NAME:by = By.CSS_SELECTORelif by == By.CLASS_NAME:by = By.CSS_SELECTORvalue = ".%s" % valueelif by == By.NAME:by = By.CSS_SELECTORvalue = '[name="%s"]' % valuereturn self.execute(Command.FIND_ELEMENT, {'using': by,'value': value})['value']def find_elements(self, by=By.ID, value=None):"""Find elements given a By strategy and locator. Prefer the find_elements_by_* methods whenpossible.:Usage:elements = driver.find_elements(By.CLASS_NAME, 'foo'):rtype: list of WebElement"""if self.w3c:if by == By.ID:by = By.CSS_SELECTORvalue = '[id="%s"]' % valueelif by == By.TAG_NAME:by = By.CSS_SELECTORelif by == By.CLASS_NAME:by = By.CSS_SELECTORvalue = ".%s" % valueelif by == By.NAME:by = By.CSS_SELECTORvalue = '[name="%s"]' % value# Return empty list if driver returns null# See https://github.com/SeleniumHQ/selenium/issues/4555return self.execute(Command.FIND_ELEMENTS, {'using': by,'value': value})['value'] or []

從以上實(shí)現(xiàn)的方法中，execute 方法實(shí)現(xiàn)在這里不在贅述實(shí)現(xiàn)，上一節(jié)已有說(shuō)明，本節(jié)主要介紹方法使用。

首先查看 find_element_by_id 方法的使用，在方法說(shuō)明中已經(jīng)介紹使用方法：

element = driver.find_element_by_id('foo')

該方法注釋說(shuō)明為（以下為了清晰說(shuō)明，使用截圖展示注釋）：

通過(guò)注釋說(shuō)明得知，find_element_by_id 方法找到id為指定值的元素，并返回這個(gè)元素。

查看具體實(shí)現(xiàn)為：

self.find_element(by=By.ID, value=id_)

以上實(shí)現(xiàn)調(diào)用了 find_element 方法，并且傳入 by的值為By.ID，隨后傳入具體值；首先查看By類（selenium.webdriver.common.by）：

class By(object):"""Set of supported locator strategies."""ID = "id"XPATH = "xpath"LINK_TEXT = "link text"PARTIAL_LINK_TEXT = "partial link text"NAME = "name"TAG_NAME = "tag name"CLASS_NAME = "class name"CSS_SELECTOR = "css selector"

這個(gè)類與Command（selenium.webdriver.remote.command）類作用類似，上節(jié)已說(shuō)明Command在這里也不過(guò)多說(shuō)明By。

在這里查看 find_element 方法實(shí)現(xiàn)：

def find_element(self, =By.ID, value=None):"""Find an element given a By strategy and locator. Prefer the find_element_by_* methods whenpossible.:Usage:element = driver.find_element(By.ID, 'foo'):rtype: WebElement"""if self.w3c:if by == By.ID:by = By.CSS_SELECTORvalue = '[id="%s"]' % valueelif by == By.TAG_NAME:by = By.CSS_SELECTORelif by == By.CLASS_NAME:by = By.CSS_SELECTORvalue = ".%s" % valueelif by == By.NAME:by = By.CSS_SEhj0ECTORvalue = '[name="%s"]' % valuereturn self.execute(Command.FIND_ELEMENT, {'using': by,'value': value})['value']

以上類首先判斷查找類型，隨后進(jìn)行值的拼接，最后把查找方式和值傳入 execute 方法中，隨后返回元素對(duì)象。

幾乎所有的元素查找方法，實(shí)現(xiàn)相同，我們簡(jiǎn)單實(shí)用這個(gè)函數(shù)。

寫代碼前，我們需要打開百度網(wǎng)址，審查元素查找id值：

得到輸入框的id值為kw，那么代碼應(yīng)該如下：

from selenium import webdriver driver = webdriver.Chrome() driver.get("https://www.baidu.com/") input = driver.find_element_by_id('kw')# print('作者博客：https://blog.csdn.net/A757291228') #支持原創(chuàng)，轉(zhuǎn)載請(qǐng)貼上鏈接

由于查到到元素后返回的是元素對(duì)象：

在元素類（selenium.webdriver.remote.webelement）中查找方法，找到如下方法：

def send_keys(self, *value):"""Simulates typing into the element.:Args:- value - A string for typing, or setting form fields. For settingfile inputs, this could be a local file path.Use this to send simple key events or to fill out form fields::form_textfield = driver.find_element_by_name('username')form_textfield.send_keys("admin")This can also be used to set file inputs.::file_input = driver.find_element_by_name('profilePic')file_input.send_keys("path/to/profilepic.gif")# Generally it's better to wrap the file path in one of the methods# in os.path to return the actual path to support cross OS testing.# file_input.send_keys(os.path.abspath("path/to/profilepic.gif"))"""# transfer file to another machine only if remote driver is used# the same behaviour as for java bindingif self.parent._is_remote:local_file = self.parent.file_detector.is_local_file(*value)if local_file is not None:value = self._upload(local_file)self._execute(Command.SEND_KEYS_TO_ELEMENT,{'text': "".join(keys_to_typing(value)),'value': keys_to_typing(value)}) # Private Methodsdef _execute(self, command, params=None):"""Executes a command against the underlying HTML element.Args:command: The name of the command to _execute as a string.params: A dictionary of named parameters to send with the command.Returns:The command's JSON response loaded into a dictionary object."""if not params:params = {}params['id'] = self._idreturn self._parent.execute(command, params)

得知 send_keys 也是通過(guò) execute 發(fā)送命令得到結(jié)果。在注釋說(shuō)明中得到了 send_keys 的使用方法為：

form_textfield.send_keys("admin")

我們修改之前的代碼：

from selenium import webdriver driver = webdriver.Chrome() driver.get("https://www.baidu.com/") input = driver.find_element_by_id('kw') input.send_keys("CSDN A757291228")# print('作者博客：https://blog.csdn.net/A757291228') #支持原創(chuàng)，轉(zhuǎn)載請(qǐng)貼上鏈接

最后還查個(gè)點(diǎn)擊即可完成自動(dòng)化搜索功能；我們繼續(xù)查看元素類，找到如下方法：

def click(self):"""Clicks the element."""self._execute(Command.CLICK_ELEMENT)

click 方法與 send_keys 方法實(shí)現(xiàn)相同，不在贅述。直接使用click方法即可進(jìn)行元素的點(diǎn)擊。查找百度搜索點(diǎn)擊按鈕的id：

修改代碼如下：

from selenium import webdriver driver = webdriver.Chrome() driver.get("https://www.baidu.com/") input = driver.find_element_by_id('kw') input.send_keys("CSDN A757291228") enter = driver.find_element_by_id('su') enter.click() # print('作者博客：https://blog.csdn.net/A757291228') #支持原創(chuàng)，轉(zhuǎn)載請(qǐng)貼上鏈接

運(yùn)行結(jié)果如下：

總結(jié)

我們簡(jiǎn)單的學(xué)習(xí)了使用 selenium 打開瀏覽器搜索 了“CSDN A757191228” ，在這個(gè)簡(jiǎn)單的例子的學(xué)習(xí)中，學(xué)習(xí)到的不僅是這個(gè)例子原本的那幾行代碼；通過(guò)實(shí)現(xiàn)分析，了解了其它功能函數(shù)所在的位置，可以通過(guò)這些功能函數(shù)，實(shí)現(xiàn)自己想要的功能！

從框架實(shí)現(xiàn)上分析可以事半功倍的學(xué)習(xí)框架的使用，以及了解框架的實(shí)現(xiàn)原理，更加利于我們的開發(fā)使用。

總結(jié)

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