WebDriver错误：UnsupportedClassVersionError：org / openqa / selenium / firefox / FirefoxDriver

Question

当我点击Selenium WebDriver中的按钮时，我得到以下错误，使用Firefox 43和Selenium 2.47.1：

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/openqa/selenium/firefox/FirefoxDriver : Unsupported major.minor version 51.0 
    at java.lang.ClassLoader.defineClass1(Native Method) 
    at java.lang.ClassLoader.defineClassCond(Unknown Source) 
    at java.lang.ClassLoader.defineClass(Unknown Source) 
    at java.security.SecureClassLoader.defineClass(Unknown Source) 
    at java.net.URLClassLoader.defineClass(Unknown Source) 
    at java.net.URLClassLoader.access$000(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) 
    at testDay1.main(testDay1.java:8)