代码中有两处出错.

对于 Firefox:你需要设置

profile.setPreference("browser.download.dir", "C:\Users\Admin\Desktop\ScreenShot\");

不要

profile.setPreference("browser.download.dir", "C:\Users\Admin\Desktop\ScreenShot\pic.jpeg");

其次，您正在设置首选项browser.download.folderlist，它是browser.download.folderList(folderList 中的大写字母).

secondly, you are setting preference browser.download.folderlist, it is browser.download.folderList (L caps in folderList).

一旦你做到了这两点，你就可以使用你的 Robot 类来执行所需的操作.

Once you have achieved this both, you can use then your Robot class to perform desired operations.

对于 Chromedriver 试试:

String downloadFilepath = "/path/to/download";
HashMap<String, Object> chromePrefs = new HashMap<String, Object>();
chromePrefs.put("profile.default_content_settings.popups", 0);
chromePrefs.put("download.default_directory", downloadFilepath);
ChromeOptions options = new ChromeOptions();
options.setExperimentalOption("prefs", chromePrefs);
DesiredCapabilities cap = DesiredCapabilities.chrome();
cap.setCapability(CapabilityType.ACCEPT_SSL_CERTS, true);
cap.setCapability(ChromeOptions.CAPABILITY, options);
WebDriver driver = new ChromeDriver(cap);

希望这会有所帮助.:)

Hope this helps. :)