一、安装selenium ，

pip install -U selenium

二、安装chromedriver

http://chromedriver.storage.googleapis.com/index.html

三、chromedriver放在python的安装根目录下面即可，为什么放到python安装的根目录下即可呢，是因为WebDriver的初始化代码里，init，有这个注释

- executable_path - Deprecated: path to the executable. If the default is used it assumes the executable is in the $PATH

实现思路

selenium自动化代码-》XXXdriver.exe-》 浏览器（ie、chrome、firefox）

通过http进行通信的，客户端是python代码或者java代码，服务端是xxxdriver

通信流程：

1、xxxdriver启动，ip+端口监听中

2、selenium webdriver跟xxxdriver建立连接，然后发送http请求

3、xxxdriver收到指令后，驱动浏览器

4、xxxxdriver要把结果返回给selenium webdriver

5、继续发下一个http请求

6、断开连接，关闭驱动服务、关闭浏览器

写一个简单的例子，可以跟一下源码，可以发现原理：是一个http请求，协议是json格式，

本质上来讲把每一个对网页的操作，都是一个接口，json格式、url、请求类型、请求数据，协议名称jsonwireprotocol

from selenium import webdriver# 打开浏览器，与浏览器建立会话# 启动chromedriver.exe，并且建立连接，会话IDdriver = webdriver.Chrome()driver.get("https://www.baidu.com")

1）点击get方法

2）然后点击execute方法，主要看response，调用了execute方法

 def execute(self, driver_command: str, params: dict = None) -> dict:"""Sends a command to be executed by a command.CommandExecutor.:Args: - driver_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 self.session_id:if not params:params = {'sessionId': self.session_id}elif 'sessionId' not in params:params['sessionId'] = self.session_idparams = self._wrap_value(params)response = self.command_executor.execute(driver_command, params)if response:self.error_handler.check_response(response)response['value'] = self._unwrap_value(response.get('value', None))return response# If the server doesn't send a response, assume the command was# a successreturn {'success': 0, 'value': None, 'sessionId': self.session_id}

3）继续点击execute（）方法，可以看到最后调用的是request方法

 def execute(self, command, params):"""Send a command to the remote server.Any path substitutions required for the URL mapped to the command should beincluded in the command parameters.:Args: - command - A string specifying the command to execute. - params - A dictionary of named parameters to send with the command as its JSON payload."""command_info = self._commands[command]assert command_info is not None, 'Unrecognised command %s' % commandpath = string.Template(command_info[1]).substitute(params)if isinstance(params, dict) and 'sessionId' in params:del params['sessionId']data = utils.dump_json(params)url = f"{self._url}{path}"return self._request(command_info[0], url, body=data)

4）点击request方法，可以看到其实就是发起了一个http请求，只要开始我们把参数传对，就会发送正确的http请求。

def _request(self, method, url, body=None):"""Send an HTTP request to the remote server.:Args: - method - A string for the HTTP method to send the request with. - url - A string for the URL to send the request to. - body - A string for request body. Ignored unless method is POST or PUT.:Returns:A dictionary with the server's parsed JSON response."""LOGGER.debug(f"{method} {url} {body}")parsed_url = parse.urlparse(url)headers = self.get_remote_connection_headers(parsed_url, self.keep_alive)response = Noneif body and method not in ("POST", "PUT"):body = Noneif self.keep_alive:response = self._conn.request(method, url, body=body, headers=headers)statuscode = response.statuselse:conn = self._get_connection_manager()with conn as http:response = http.request(method, url, body=body, headers=headers)statuscode = response.statusif not hasattr(response, 'getheader'):if hasattr(response.headers, 'getheader'):response.getheader = lambda x: response.headers.getheader(x)elif hasattr(response.headers, 'get'):response.getheader = lambda x: response.headers.get(x)data = response.data.decode('UTF-8')LOGGER.debug(f"Remote response: status={response.status} | data={data} | headers={response.headers}")try:if 300 <= statuscode < 304:return self._request('GET', response.getheader('location'))if 399 < statuscode <= 500:return {'status': statuscode, 'value': data}content_type = []if response.getheader('Content-Type'):content_type = response.getheader('Content-Type').split(';')if not any([x.startswith('image/png') for x in content_type]):try:data = utils.load_json(data.strip())except ValueError:if 199 < statuscode < 300:status = ErrorCode.SUCCESSelse:status = ErrorCode.UNKNOWN_ERRORreturn {'status': status, 'value': data.strip()}# Some drivers incorrectly return a response# with no 'value' field when they should return null.if 'value' not in data:data['value'] = Nonereturn dataelse:data = {'status': 0, 'value': data}return datafinally:LOGGER.debug("Finished Request")response.close()

1、退出会话，关闭浏览器，关闭chromedriver

driver.quit()，这个退出

driver.close()，关闭当前的窗口