public void login(){

         WebDriver driver = new ChromeDriver();

         driver.get("http://IP:Port/client/login.html");

         driver.findElement(By.id("username")).sendKeys("admin");

         driver.findElement(By.id("pwd")).sendKeys("111111");

         driver.findElement(By.className("btn btn-primary")).click();

     }

Starting ChromeDriver (v2.9.248315) on port 8850

Starting ChromeDriver (v2.9.248315) on port 26269

Exception in thread "main" org.openqa.selenium.IllegalLocatorException: Compound class names are not supported. Consider searching for one class name and filtering the results.

Build info: version: '2.23.1', revision: '17143', time: '2012-06-08 18:59:28'

System info: os.name: 'Windows 7', os.arch: 'x86', os.version: '6.1', java.version: '1.7.0_60'

Driver info: driver.version: unknown

    at org.openqa.selenium.By.className(By.java:)

    at omstest.find.main(find.java:52)