How to download a file from a website ?

@BeforeMethod
        private void openBrowser()

{
        try

{
        FirefoxProfile fxProfile = new FirefoxProfile();
        fxProfile.setPreference("browser.download.folderList",2);
        fxProfile.setPreference("browser.download.manager.showWhenStarting",false);
        fxProfile.setPreference("browser.download.dir","/home/chinna/Desktop/Locust/pdf"); // ADD YOUR DOWNLOAD PATH
        fxProfile.setPreference("browser.helperApps.neverAsk.saveToDisk","application/pdf");
        fxProfile.setPreference("browser.download.manager.showWhenStarting", false);
        fxProfile.setPreference("browser.download.manager.focusWhenStarting", false);
        fxProfile.setPreference("browser.helperApps.alwaysAsk.force", false);
        fxProfile.setPreference("browser.download.manager.alertOnEXEOpen", false);
        fxProfile.setPreference("browser.download.manager.closeWhenDone", false);
        fxProfile.setPreference("browser.download.manager.showAlertOnComplete", false);
        fxProfile.setPreference("browser.download.manager.useWindow", false);
        fxProfile.setPreference("browser.download.manager.showWhenStarting",false);
        fxProfile.setPreference("services.sync.prefs.sync.browser.download.manager.showWhenStarting", false);
        fxProfile.setPreference( "pdfjs.disabled", true );
        driver = new FirefoxDriver(fxProfile);
        driver.manage().timeouts().implicitlyWait(15,TimeUnit.SECONDS);
        driver.manage().window().maximize();
        driver.get("http://seleniumsubbu.blogspot.in/");
        Thread.sleep(2000);
        waitForTitleToPresent("Selenium 2+ Experiance | TechLearn");
        }catch(Throwable t)

{
        System.err.println("There is an issue in launching the application ,please check "+t); 
        }        

}
        private void waitForTitleToPresent(String locator)

{
        WebDriverWait wait=new WebDriverWait(driver,15);
        wait.until(ExpectedConditions.titleIs(locator));
        }
@Test
        public void PDFDOWNLOAD() throws InterruptedException

{
        Thread.sleep(1000);
        driver.switchTo().frame(driver.findElement(By.className("pdf")));
        driver.findElement(By.id("download")).click();
        Thread.sleep(5000);        

}