pythonselenium如何控制浏览器_Selenium WebDriver原理（二）：Selenium是如何操纵浏览器的？...

前言

上一篇文章《selenium webdriver 是怎么运行的》用了一个简单的例子——搭出租车，形象地讲解selenium webdriver 是如何运行的，而这一篇文章可以理解为深入了解selenium是如何和浏览器驱动进行交互，也可以认为是乙醇老师写的《selenium是如何启动浏览器的》文章的2.0版本。

环境准备：

python 3.0以上

selenium 3.0以上

浏览器 Chrome

浏览器驱动 ChromeDriver

接口测试工具

小编的环境：

python 3.6.4

selenium 3.13

浏览器：Chrome 68

浏览器驱动： ChromeDriver 2.38

接口测试工具：python requests

首先，我们运行下述代码块

#encoding:utf8

from selenium import webdriver

import logging

logging.basicConfig(level=logging.DEBUG)

dr = webdriver.Chrome()

dr.implicitly_wait(10)

#打开深圳-逸遥博客园首页

dr.get('https://www.cnblogs.com/snailrunning')

#定位深圳-逸遥第一篇博文标题

el = dr.find_element_by_css_selector('.postTitle a')

#点击第一篇博文标题

el.click()

运行结果：

DEBUG:selenium.webdriver.remote.remote_connection:

POST http://127.0.0.1:4102/session

{"capabilities": {"firstMatch": [{}], "alwaysMatch": {"browserName": "chrome", "platformName": "any", "goog:chromeOptions": {"extensions": [], "args": []}}},

"desiredCapabilities": {"browserName": "chrome", "version": "", "platform": "ANY", "goog:chromeOptions": {"extensions": [], "args": []}}}

DEBUG:selenium.webdriver.remote.remote_connection:

b'{"sessionId":"7cbbff953318267ef0089dc66f127051",

"status":0,

"value":{"acceptInsecureCerts":false,"acceptSslCerts":false,"applicationCacheEnabled":false,"browserConnectionEnabled":false,"browserName":"chrome","chrome":{"chromedriverVersion":"2.38.552522 (437e6fbedfa8762dec75e2c5b3ddb86763dc9dcb)","userDataDir":"C:\\\\Users\\\\lenovo\\\\AppData\\\\Local\\\\Temp\\\\scoped_dir13812_4179"},"cssSelectorsEnabled":true,"databaseEnabled":false,"handlesAlerts":true,"hasTouchScreen":false,"javascriptEnabled":true,"locationContextEnabled":true,"mobileEmulationEnabled":false,"nativeEvents":true,"networkConnectionEnabled":false,"pageLoadStrategy":"normal","platform":"Windows NT","rotatable":false,"setWindowRect":true,"takesHeapSnapshot":true,"takesScreenshot":true,"unexpectedAlertBehaviour":"","version":"68.0.3440.106","webStorageEnabled":true}}'

DEBUG:selenium.webdriver.remote.remote_connection:Finished Request

DEBUG:selenium.webdriver.remote.remote_connection:

POST

http://127.0.0.1:4102/session/7cbbff953318267ef0089dc66f127051/timeouts/implicit_wait

{"ms": 10000.0, "sessionId": "7cbbff953318267ef0089dc66f127051"}

DEBUG:selenium.webdriver.remote.remote_connection:

b'{"sessionId":"7cbbff953318267ef0089dc66f127051","status":0,"value":null}'

DEBUG:selenium.webdriver.remote.remote_connection:Finished Request

DEBUG:selenium.webdriver.remote.remote_connection:

POST http://127.0.0.1:4102/session/7cbbff953318267ef0089dc66f127051/url

{"url": "https://www.cnblogs.com/snailrunning", "sessionId": "7cbbff953318267ef0089dc66f127051"}

DEBUG:selenium.webdriver.remote.remote_connection:

b'{"sessionId":"7cbbff953318267ef0089dc66f127051","status":0,"value":null}'

DEBUG:selenium.webdriver.remote.remote_connection:Finished Request

DEBUG:selenium.webdriver.remote.remote_connection:

POST

http://127.0.0.1:4102/session/7cbbff953318267ef0089dc66f127051/element

{"using": "css selector", "value": ".postTitle a", "sessionId": "7cbbff953318267ef0089dc66f127051"}

DEBUG:selenium.webdriver.remote.remote_connection:

b'{"sessionId":"7cbbff953318267ef0089dc66f127051","status":0,"value":{"ELEMENT":"0.3612689441010788-1"}}'

DEBUG:selenium.webdriver.remote.remote_connection:Finished Request

DEBUG:selenium.webdriver.remote.remote_connection:

POST http://127.0.0.1:4102/session/7cbbff953318267ef0089dc66f127051/element/0.3612689441010788-1/click

{"id": "0.3612689441010788-1", "sessionId": "7cbbff953318267ef0089dc66f127051"}

DEBUG:selenium.webdriver.remote.remote_connection:

b'{"sessionId":"7cbbff953318267ef0089dc66f127051","status":0,"value":null}'

DEBUG:selenium.webdriver.remote.remote_connection:Finished Request

从上述代码运行结果，我们可以得出以下结论

对于每个Selenium命令，都会创建一个HTTP请求并将其发送到浏览器驱动程序

每一个命令的执行结果都会返回给自动化代码

ChromeDirver创建session时打开了浏览器

Selenium代码和浏览器驱动的交互都根据ChromeDriver创建的sessionId

文章到这里，很多测试的同学看了会头晕，没关系，我们现在先根据上述返回的结果来拆解一下请求的接口和返回，以及我们通过接口工具来模拟Selenium自动化代码来操纵浏览器

1、启动浏览器接口

请求方式：post

请求url : http://127.0.0.1:4102/session

请求body: {"capabilities": {"firstMatch": [{}], "alwaysMatch": {"browserName": "chrome", "platformName": "any", "goog:chromeOptions": {"extensions": [], "args": []}}},

"desiredCapabilities": {"browserName": "chrome", "version": "", "platform": "ANY", "goog:chromeOptions": {"extensions": [], "args": []}}}

返回body : b'{"sessionId":"7cbbff953318267ef0089dc66f127051",

"status":0,

"value":{"acceptInsecureCerts":false,"acceptSslCerts":false,"applicationCacheEnabled":false,"browserConnectionEnabled":false,"browserName":"chrome","chrome":{"chromedriverVersion":"2.38.552522 (437e6fbedfa8762dec75e2c5b3ddb86763dc9dcb)","userDataDir":"C:\\\\Users\\\\lenovo\\\\AppData\\\\Local\\\\Temp\\\\scoped_dir13812_4179"},"cssSelectorsEnabled":true,"databaseEnabled":false,"handlesAlerts":true,"hasTouchScreen":false,"javascriptEnabled":true,"locationContextEnabled":true,"mobileEmulationEnabled":false,"nativeEvents":true,"networkConnectionEnabled":false,"pageLoadStrategy":"normal","platform":"Windows NT","rotatable":false,"setWindowRect":true,"takesHeapSnapshot":true,"takesScreenshot":true,"unexpectedAlertBehaviour":"","version":"68.0.3440.106","webStorageEnabled":true}}'

1.1 开启ChomeDriver

Starting ChromeDriver 2.38.552522 开启ChromeDriver 版本号2.38.552522

(437e6fbedfa8762dec75e2c5b3ddb86763dc9dcb) on port 9515 监听的端口是9515

Only local connections are allowed. ；只允许本地链接

1.2 构造请求

请求方式：POST

请求地址：http://localhost:9515/session

请求body ：{"capabilities": {"firstMatch": [{}], "alwaysMatch": {"browserName": "chrome", "platformName": "any", "goog:chromeOptions": {"extensions": [], "args": []}}},

"desiredCapabilities": {"browserName": "chrome", "version": "", "platform": "ANY", "goog:chromeOptions": {"extensions": [], "args": []}}}

1.3 使用python requests 向 ChromeDriver发送请求

#encoding:utf8

import requests

session_url = 'http://localhost:9515/session'

session_pars = {"capabilities": {"firstMatch": [{}], \

"alwaysMatch": {"browserName": "chrome",\

"platformName": "any", \

"goog:chromeOptions": {"extensions": [], "args": []}}}, \

"desiredCapabilities": {"browserName": "chrome", \

"version": "", "platform": "ANY", "goog:chromeOptions": {"extensions": [], "args": []}}}

r_session = requests.post(session_url,json=session_pars)

print(r_session.json())

此时Chrome浏览器被打开

1.4 查看返回结果

{

"sessionId": "b2801b5dc58b15e76d0d3295b04d295c",

"status": 0,

"value": {

"acceptInsecureCerts": false,

"acceptSslCerts": false,

"applicationCacheEnabled": false,

"browserConnectionEnabled": false,

"browserName": "chrome",

"chrome": {

"chromedriverVersion": "2.38.552522 (437e6fbedfa8762dec75e2c5b3ddb86763dc9dcb)",

"userDataDir": "C:\\Users\\lenovo\\AppData\\Local\\Temp\\scoped_dir1792_5142"

},

"cssSelectorsEnabled": true,

"databaseEnabled": false,

"handlesAlerts": true,

"hasTouchScreen": false,

"javascriptEnabled": true,

"locationContextEnabled": true,

"mobileEmulationEnabled": false,

"nativeEvents": true,

"networkConnectionEnabled": false,

"pageLoadStrategy": "normal",

"platform": "Windows NT",

"rotatable": false,

"setWindowRect": true,

"takesHeapSnapshot": true,

"takesScreenshot": true,

"unexpectedAlertBehaviour": "",

"version": "68.0.3440.106",

"webStorageEnabled": true

}

}

2、打开深圳-逸遥的博客园

2.1 构造请求

请求方式：POST

请求地址：http://localhost:9515/session/:sessionId/url

注意：上述地址中的 ":sessionId"

要用启动浏览器的请求返回结果中的sessionId的值

例如：我刚刚发送请求，启动浏览器，返回结果中"sessionId": "b2801b5dc58b15e76d0d3295b04d295c"

然后我构造导航到"深圳-逸遥的博客园"的请求地址

请求地址：http://localhost:9515/session/b2801b5dc58b15e76d0d3295b04d295c/url

请求body ：{"url": "https://www.cnblogs.com/snailrunning", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

2.2 使用python requests 向 ChromeDriver发送请求

#encoding:utf8

import requests

url = 'http://localhost:9515/session/b2801b5dc58b15e76d0d3295b04d295c/url'

pars = {"url": "https://www.cnblogs.com/snailrunning", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

r = requests.post(url,json=pars)

print(r.json())

浏览器打开”深圳-逸遥“的博客园

2.3 查看请求返回结果

{'sessionId': 'b2801b5dc58b15e76d0d3295b04d295c', 'status': 0, 'value': None}

3、定位”深圳-逸遥“第一篇博文的标题

3.1 构造请求

请求方式：POST

请求地址：http://localhost:9515/session/:sessionId/element

注意：上述地址中的 ":sessionId"

要用启动浏览器的请求返回结果中的sessionId的值

例如：我刚刚发送请求，启动浏览器，返回结果中"sessionId": "b2801b5dc58b15e76d0d3295b04d295c"

然后我构造查找页面元素的请求地址

请求地址：http://localhost:9515/session/b2801b5dc58b15e76d0d3295b04d295c/element

请求body ：{"using": "css selector", "value": ".postTitle a", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

3.2 使用python requests 向 ChromeDriver发送请求

#encoding:utf8

import requests

url = 'http://localhost:9515/session/b2801b5dc58b15e76d0d3295b04d295c/element'

pars = {"using": "css selector", "value": ".postTitle a", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

r = requests.post(url,json=pars)

print(r.json())

3.3 查看请求返回的结果

{'sessionId': 'b2801b5dc58b15e76d0d3295b04d295c', 'status': 0, 'value': {'ELEMENT': '0.11402119390850629-1'}}

返回结果中的{'ELEMENT': '0.11402119390850629-1'}

官方文档称为：找到的元素的WebElement JSON对象，表示页面上的DOM元素，同时服务器分配给ELEMENT的值是不透明的(随机的) 这个ELEMENT的值会在针对该元素发出的所有后续命令中使用。

### 4、点击”深圳-逸遥“博客第一篇博文的标题

4.1 构造请求

```

请求方式：POST

请求地址：http://localhost:9515/session/:sessionId/element/:id/click

注意：上述地址中的 ":sessionId"

要用启动浏览器的请求返回结果中的sessionId的值

:id 要用元素定位请求后返回ELEMENT的值

例如：我刚刚发送请求，启动浏览器，返回结果中"sessionId": "b2801b5dc58b15e76d0d3295b04d295c"

元素定位,返回ELEMENT的值"0.11402119390850629-1"

请求body ：{"id": "0.11402119390850629-1", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

4.2 使用python requests 向 ChromeDriver发送请求

encoding:utf8

import requests

url = 'http://localhost:9515/session/b2801b5dc58b15e76d0d3295b04d295c/element/0.11402119390850629-1/click'

pars ={"id": "0.5930642995574296-1", "sessionId": "b2801b5dc58b15e76d0d3295b04d295c"}

r = requests.post(url,json=pars)

print(r.json())

#### 浏览器导航到“深圳-逸遥”首页的第一篇博文

![image](https://wx2.sinaimg.cn/mw690/6e01037bgy1fucuuhddl9j20jk0o9abt.jpg)

4.3 查看请求返回的结果

{'sessionId': 'b2801b5dc58b15e76d0d3295b04d295c', 'status': 0, 'value': None}

#### 文章末尾再炒一下旧饭

- 对于每个Selenium命令，都会创建一个HTTP请求并将其发送到浏览器驱动程序

- 每一个命令的执行结果都会返回给自动化代码

- 响应状态代码 status 等于0 ，即表示命令执行成功

- ChromeDirver创建session时打开了浏览器

- Selenium代码和浏览器驱动的交互都根据ChromeDriver创建的sessionId

#### 附带上述操作相关的接口文档——[selenium webdriver JsonWireProtocol](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol)

[WebDriver JsonWireProtocol 基本术语和概念 ](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#basic-terms-and-concepts)

[请求响应说明](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#messages)

[启动浏览器，创建sessionId](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#session-1)

[导航指定url](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#post-sessionsessionidurl)

[元素定位](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#sessionsessionidelement)

[元素点击操作](https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#sessionsessionidelementidclick)

#### 参考文章

[乙醇 - selenium是如何启动浏览器的](https://www.cnblogs.com/nbkhic/p/9249330.html)

#### 推荐阅读

[乙醇 - selenium是如何启动浏览器的](https://www.cnblogs.com/nbkhic/p/9249330.html)

[深圳-逸遥 - Selenium WebDriver原理(一)：Selenium WebDriver 是怎么工作的？](https://www.cnblogs.com/snailrunning/p/9413446.html)

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原文链接：https://blog.csdn.net/weixin_33462540/article/details/113499283