下面是我在Java文件中捕获源代码的java代码

private static void getHTMLSourceFromURL(String url,String fileName) {

    WebDriver driver = new FirefoxDriver();
    driver.get(url);

    try {
        Thread.sleep(5000);   //the page gets loaded completely

        List<String> pageSource = new ArrayList<String>(Arrays.asList(driver.getPageSource().split("\n")));

        writeTextToFile(pageSource,originalFile);

    } catch (InterruptedException e) {
        e.printStackTrace();
    }

    System.out.println("quitting webdriver");
    driver.quit();
}

/**
 * creates file with fileName and writes the content
 * 
 * @param content
 * @param fileName
 */
private static void writeTextToFile(List<String> content,String fileName) {
    PrintWriter pw = null;
    String outputFolder = ".";
    File output = null;
    try {
        File dir = new File(outputFolder + '/' + "HTML Sources");
        if (!dir.exists()) {
            boolean success = dir.mkdirs();
            if (success == false) {
                try {
                    throw new Exception(dir + " could not be created");
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

        output = new File(dir + "/" + fileName);
        if (!output.exists()) {
            try {
                output.createNewFile();
            } catch (IOException ioe) {
                ioe.printStackTrace();
            }
        }
        pw = new PrintWriter(new FileWriter(output,true));
        for (String line : content) {
            pw.print(line);
            pw.print("\n");
        }
    } catch (IOException ioe) {
        ioe.printStackTrace();
    } finally {
        pw.close();
    }

}

有人可以为此解释为什么会发生这种情况吗？ WebDriver如何呈现页面？浏览器如何显示源代码？