selenium不能启动firefox浏览器，怎么办？

 1 java.lang.IllegalStateException: The path to the driver executable must be set by the webdriver.gecko.driver system property; for more information, see https://github.com/mozilla/geckodriver. The latest version can be downloaded from https://github.com/mozilla/geckodriver/releases
 2     at com.google.common.base.Preconditions.checkState(Preconditions.java:754)
 3     at org.openqa.selenium.remote.service.DriverService.findExecutable(DriverService.java:124)
 4     at org.openqa.selenium.firefox.GeckoDriverService.access$100(GeckoDriverService.java:41)
 5     at org.openqa.selenium.firefox.GeckoDriverService$Builder.findDefaultExecutable(GeckoDriverService.java:141)
 6     at org.openqa.selenium.remote.service.DriverService$Builder.build(DriverService.java:339)
 7     at org.openqa.selenium.firefox.FirefoxDriver.toExecutor(FirefoxDriver.java:158)
 8     at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:120)
 9     at org.openqa.selenium.firefox.FirefoxDriver.<init>(FirefoxDriver.java:98)
…………

      @Test
      public void setUp() throws Exception {
          
        try {

            driver = new FirefoxDriver();
            driver.get("https://www.baidu.com/");
            System.out.print(driver.getTitle());
            driver.quit();
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
      }

 1       @Test
 2       public void setUp() throws Exception {
 3           
 4         try {
 5             System.setProperty("webdriver.firefox.marionette",
 6                     "C:\\Program Files (x86)\\Mozilla Firefox\\geckodriver.exe");
 7             driver = new FirefoxDriver();
 8             driver.get("https://www.baidu.com/");
 9             System.out.print(driver.getTitle());
10             driver.quit();
11         } catch (Exception e) {
12             // TODO Auto-generated catch block
13             e.printStackTrace();
14         }
15       }