1. 没有找到类的异常(NoClassDefFoundError)
  异常如下:
Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/base/Function
at com.yy.baidu.testBaidu.main(testBaidu.java:12)
Caused by: java.lang.ClassNotFoundException: com.google.common.base.Function
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 1 more
  解决办法:
  此问题通常的包引入的少了,少Selenium包,如下图,除了要引入selenium-java-2.52.0.jar包以外,还需要引入libs目录下的包。
  package
  2. 没有找到Firefox的路径
  异常如下:
Exception in thread "main" org.openqa.selenium.WebDriverException: Cannot find firefox binary in PATH. Make sure firefox is installed. OS appears to be: WIN8_1
Build info: version: '2.52.0', revision: '4c2593c', time: '2016-02-11 19:03:33'
System info: host: 'DESKTOP-VFHU33A', ip: '192.168.3.115', os.name: 'Windows 8.1', os.arch: 'amd64', os.version: '6.3', java.version: '1.7.0_79'
Driver info: driver.version: FirefoxDriver
at org.openqa.selenium.firefox.internal.Executable.<init>(Executable.java:74)
at org.openqa.selenium.firefox.FirefoxBinary.<init>(FirefoxBinary.java:60)
at org.openqa.selenium.firefox.FirefoxBinary.<init>(FirefoxBinary.java:56)
at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:120)
at com.yy.baidu.testBaidu.main(testBaidu.java:12)
  解决办法:
  方法1. 重装Firefox,这个问题简单的办法是重新按照Firefox,稳稳的
  方法2. 用System.setPropert方法设置webdriver.firefox.bin的值,如:
public class testBaidu {
public static void main(String[] args){
System.setProperty("webdriver.firefox.bin","D:\Mozilla Firefox\firefox.exe");
System.out.println("srart selenium ");
WebDriver driver = new FirefoxDriver();
driver.get("http://www.baidu.com");
WebElement txtbox = driver.findElement(By.id("kw"));
txtbox.sendKeys("selenium java");
WebElement btn = driver.findElement(By.id("su"));
btn.click();
System.out.println("end selenium");
}
}
  方法3. 用FirefoxBinary类和public FirefoxDriver(FirefoxBinary binary, FirefoxProfile profile)这个构造方法,直接上代码:
public class testBaidu {
public static void main(String[] args){
File pathToFirefoxBinary = new File("D:\Mozilla Firefox\firefox.exe");
FirefoxBinary firefoxbin = new FirefoxBinary(pathToFirefoxBinary);
WebDriver driver = new FirefoxDriver(firefoxbin,null);//这里使用这个构造方法。
System.out.println("srart selenium ");
WebDriver driver = new FirefoxDriver();
driver.get("http://www.baidu.com");
WebElement txtbox = driver.findElement(By.id("kw"));
txtbox.sendKeys("selenium java");
WebElement btn = driver.findElement(By.id("su"));
btn.click();
System.out.println("end selenium");
}
}
  注:有人可能会不知道webdriver.firefox.bin,可以看一下源码,其中
  org.openqa.selenium.firefox.internal.Executable.locateFirefoxBinaryFromSystemProperty()
  方法第一句
  String binaryName = System.getProperty(FirefoxDriver.SystemProperty.BROWSER_BINARY);
  说明默认的时候取的是这个值,重新设置一下。
  后附上查看Selenium源码的方法
  1. 右键selenium引入的jar包“selenium-java-2.52.0.jar”选择Properties

  2. 点击External location -> External File... -> 找到“selenium-java-2.52.0-srcs.jar”

  设置好了之后,可以查看Selenium的源码了。