问题
I\'m using python-selenium and Chrome 59 and trying to automate a simple download sequence. When I launch the browser normally, the download works, but when I do so in headless mode, the download doesn\'t work.
# Headless implementation
from selenium import webdriver
chromeOptions = webdriver.ChromeOptions()
chromeOptions.add_argument(\"headless\")
driver = webdriver.Chrome(chrome_options=chromeOptions)
driver.get(\'https://www.mockaroo.com/\')
driver.find_element_by_id(\'download\').click()
# ^^^ Download doesn\'t start
# Normal Mode
from selenium import webdriver
driver = webdriver.Chrome()
driver.get(\'https://www.mockaroo.com/\')
driver.find_element_by_id(\'download\').click()
# ^^^ Download works normally
I\'ve even tried adding a default path:
prefs = {\"download.default_directory\" : \"/Users/Chetan/Desktop/\"}
chromeOptions.add_argument(\"headless\")
chromeOptions.add_experimental_option(\"prefs\",prefs)
Adding a default path works in the normal implementation, but the same problem persists in the headless version.
How do I get the download to start in headless mode?
回答1:
Yes, it's a "feature", for security. As mentioned before here is the bug discussion: https://bugs.chromium.org/p/chromium/issues/detail?id=696481
Support was added in chrome version 62.0.3196.0 or above to enable downloading.
Here is a python implementation. I had to add the command to the chromedriver commands. I will try to submit a PR so it is included in the library in the future.
def enable_download_in_headless_chrome(self, driver, download_dir):
# add missing support for chrome "send_command" to selenium webdriver
driver.command_executor._commands["send_command"] = ("POST", '/session/$sessionId/chromium/send_command')
params = {'cmd': 'Page.setDownloadBehavior', 'params': {'behavior': 'allow', 'downloadPath': download_dir}}
command_result = driver.execute("send_command", params)
For reference here is a little repo to demonstrate how to use this: https://github.com/shawnbutton/PythonHeadlessChrome
回答2:
This is a feature of Chrome to prevent from software to download files to your computer. There is a workaround though. Read more about it here.
What you need to do is enable it via DevTools, Something like that:
async function setDownload () {
const client = await CDP({tab: 'ws://localhost:9222/devtools/browser'});
const info = await client.send('Browser.setDownloadBehavior', {behavior : "allow", downloadPath: "/tmp/"});
await client.close();
}
This is the solution some one gave in the mentioned topic. Here is his comment.
回答3:
Here's a working example for Python based on Shawn Button's answer. I've tested this with Chromium 68.0.3440.75 & chromedriver 2.38
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
chrome_options = Options()
chrome_options.add_experimental_option("prefs", {
"download.default_directory": "/path/to/download/dir",
"download.prompt_for_download": False,
})
chrome_options.add_argument("--headless")
driver = webdriver.Chrome(chrome_options=chrome_options)
driver.command_executor._commands["send_command"] = ("POST", '/session/$sessionId/chromium/send_command')
params = {'cmd': 'Page.setDownloadBehavior', 'params': {'behavior': 'allow', 'downloadPath': "/path/to/download/dir"}}
command_result = driver.execute("send_command", params)
driver.get('http://download-page.url/')
driver.find_element_by_css_selector("#download_link").click()
回答4:
Maybe the website that you handle returns different HTML pages for browsers, means the XPath or Id that you want maybe differently in headless browser. Try to download pageSource in headless browser and open it as HTML page to see the Id or XPath that you want. You can see this as c# example How to hide FirefoxDriver (using Selenium) without findElement function error in PhantomDriver? .
回答5:
Usually it's redundant seeing the same thing just written in another language, but because this issue drove me crazy, I hope I'm saving someone else from the pain... so here's the C# version of Shawn Button's answer (tested with headless chrome=71.0.3578.98, chromedriver=2.45.615279, platform=Linux 4.9.125-linuxkit x86_64)):
var enableDownloadCommandParameters = new Dictionary<string, object>
{
{ "behavior", "allow" },
{ "downloadPath", downloadDirectoryPath }
};
var result = ((OpenQA.Selenium.Chrome.ChromeDriver)driver).ExecuteChromeCommandWithResult("Page.setDownloadBehavior", enableDownloadCommandParameters);
回答6:
A full working example for JavaScript with selenium-cucumber-js / selenium-webdriver:
const chromedriver = require('chromedriver');
const selenium = require('selenium-webdriver');
const command = require('selenium-webdriver/lib/command');
const chrome = require('selenium-webdriver/chrome');
module.exports = function() {
const chromeOptions = new chrome.Options()
.addArguments('--no-sandbox', '--headless', '--start-maximized', '--ignore-certificate-errors')
.setUserPreferences({
'profile.default_content_settings.popups': 0, // disable download file dialog
'download.default_directory': '/tmp/downloads', // default file download location
"download.prompt_for_download": false,
'download.directory_upgrade': true,
'safebrowsing.enabled': false,
'plugins.always_open_pdf_externally': true,
'plugins.plugins_disabled': ["Chrome PDF Viewer"]
})
.windowSize({width: 1600, height: 1200});
const driver = new selenium.Builder()
.withCapabilities({
browserName: 'chrome',
javascriptEnabled: true,
acceptSslCerts: true,
path: chromedriver.path
})
.setChromeOptions(chromeOptions)
.build();
driver.manage().window().maximize();
driver.getSession()
.then(session => {
const cmd = new command.Command("SEND_COMMAND")
.setParameter("cmd", "Page.setDownloadBehavior")
.setParameter("params", {'behavior': 'allow', 'downloadPath': '/tmp/downloads'});
driver.getExecutor().defineCommand("SEND_COMMAND", "POST", `/session/${session.getId()}/chromium/send_command`);
return driver.execute(cmd);
});
return driver;
};
The key part is:
driver.getSession()
.then(session => {
const cmd = new command.Command("SEND_COMMAND")
.setParameter("cmd", "Page.setDownloadBehavior")
.setParameter("params", {'behavior': 'allow', 'downloadPath': '/tmp/downloads'});
driver.getExecutor().defineCommand("SEND_COMMAND", "POST", `/session/${session.getId()}/chromium/send_command`);
return driver.execute(cmd);
});
Tested with:
- Chrome 67.0.3396.99
- Chromedriver 2.36.540469
- selenium-cucumber-js 1.5.12
- selenium-webdriver 3.0.0
回答7:
Following is the equivalent in Java, selenium, chromedriver and chrome v 71.x. The code in is the key to allow saving of downloads Additional jars: com.fasterxml.jackson.core, com.fasterxml.jackson.annotation, com.fasterxml.jackson.databind
System.setProperty("webdriver.chrome.driver","C:\libraries\chromedriver.exe");
String downloadFilepath = "C:\\Download";
HashMap<String, Object> chromePreferences = new HashMap<String, Object>();
chromePreferences.put("profile.default_content_settings.popups", 0);
chromePreferences.put("download.prompt_for_download", "false");
chromePreferences.put("download.default_directory", downloadFilepath);
ChromeOptions chromeOptions = new ChromeOptions();
chromeOptions.setBinary("C:\\pathto\\Chrome SxS\\Application\\chrome.exe");
//ChromeOptions options = new ChromeOptions();
//chromeOptions.setExperimentalOption("prefs", chromePreferences);
chromeOptions.addArguments("start-maximized");
chromeOptions.addArguments("disable-infobars");
//HEADLESS CHROME
**chromeOptions.addArguments("headless");**
chromeOptions.setExperimentalOption("prefs", chromePreferences);
DesiredCapabilities cap = DesiredCapabilities.chrome();
cap.setCapability(CapabilityType.ACCEPT_SSL_CERTS, true);
cap.setCapability(ChromeOptions.CAPABILITY, chromeOptions);
**ChromeDriverService driverService = ChromeDriverService.createDefaultService();
ChromeDriver driver = new ChromeDriver(driverService, chromeOptions);
Map<String, Object> commandParams = new HashMap<>();
commandParams.put("cmd", "Page.setDownloadBehavior");
Map<String, String> params = new HashMap<>();
params.put("behavior", "allow");
params.put("downloadPath", downloadFilepath);
commandParams.put("params", params);
ObjectMapper objectMapper = new ObjectMapper();
HttpClient httpClient = HttpClientBuilder.create().build();
String command = objectMapper.writeValueAsString(commandParams);
String u = driverService.getUrl().toString() + "/session/" + driver.getSessionId() + "/chromium/send_command";
HttpPost request = new HttpPost(u);
request.addHeader("content-type", "application/json");
request.setEntity(new StringEntity(command));**
try {
httpClient.execute(request);
} catch (IOException e2) {
// TODO Auto-generated catch block
e2.printStackTrace();
}**
//Continue using the driver for automation
driver.manage().window().maximize();
回答8:
I solved this problem by using the workaround shared by @Shawn Button and using the full path for the 'downloadPath' parameter. Using a relative path did not work and give me the error.
Versions:
Chrome Version 75.0.3770.100 (Official Build) (32-bit)
ChromeDriver 75.0.3770.90
来源：https://stackoverflow.com/questions/45631715/downloading-with-chrome-headless-and-selenium