JSOUP

Jsoup is a java html parser. It is a java library that is used to parse HTML document. Jsoup provides api to extract and manipulate data from URL or HTML file. It uses DOM, CSS and Jquery-like methods for extracting and manipulating file.

Document document = Jsoup.parse(html);</br>
Element sampleDiv = document.getElementById("sampleDiv");</br>
Elements links = sampleDiv.getElementsByTag("a")</br>
System.out.println("Relative Link: " + link.attr("href"));</br>
System.out.println("Absolute Link: " + link.attr("abs:href"));</br>
System.out.println("Absolute Link: " + link.absUrl("href"));</br></br>

Where
document − document object represents the HTML DOM.
Jsoup − main class to parse the given HTML String.
html − HTML String.
sampleDiv − Element object represent the html node element identified by id "sampleDiv".
links − Elements object represents the multiple node elements identified by tag "a".
link.attr − provides the value of href present in anchor tag. It may be relative or absolute.
link.attr − provides the absolute url after resolving against the document's base URI.
link.absUrl − provides the absolute url after resolving against the document's base URI.

Unirest(Ajax/dynamic)

1. Use a headless browser
   

• e.g. HtmlUnit For java
  
• musch slower
  
• easier to detect
  

2. Reverse engineering and calling the undocumented API directly
   

• use the browser's developer tools
  
• very fast
  
• mostly returns already structured data(XML or JSON)
  

Selenium webdriver (geckoDriver) - Headless Mode

How to build this project

1. Download the project and import into Intellij

2. Set the build path which must have the following libraries

• selenium-server-standalone
• geckodriver

Source code

       System.setProperty("webdriver.gecko.driver","c:\\geckodriver.exe");
       FirefoxBinary firefoxBinary = new FirefoxBinary();
       firefoxBinary.addCommandLineOptions("--headless");
       FirefoxOptions firefoxOptions = new FirefoxOptions();
       firefoxOptions.setBinary(firefoxBinary);
       FirefoxDriver driver = new FirefoxDriver(firefoxOptions);
       driver.manage().timeouts().implicitlyWait(45, TimeUnit.SECONDS);
       driver.get(url);
       // parse html
       String html = driver.getPageSource();
       Document doc = Jsoup.parse(html);

For Maven User

       <dependency>
           <groupId>com.mashape.unirest</groupId>
           <artifactId>unirest-java</artifactId>
           <version>1.4.9</version>
       </dependency>
       <dependency>
           <!-- jsoup HTML parser library @ https://jsoup.org/ -->
           <groupId>org.jsoup</groupId>
           <artifactId>jsoup</artifactId>
           <version>1.9.1</version>
       </dependency>
       <dependency>
           <groupId>com.fasterxml.jackson.core</groupId>
           <artifactId>jackson-databind</artifactId>
           <version>2.7.4</version>
       </dependency>

Data Loading Dynamically

Scroll Down:

import org.openqa.selenium.JavascriptExecutor;
WebDriver driver = new FirefoxDriver();
JavascriptExecutor jse = (JavascriptExecutor)driver;
jse.executeScript("scroll(0, 250)"); //y value '250' can be altered

Scroll up:

JavascriptExecutor jse = (JavascriptExecutor)driver;
jse.executeScript("scroll(250, 0)"); //x value '250' can be altered

Scroll bottom of the Page:

JavascriptExecutor jse = (JavascriptExecutor)driver;
jse.executeScript("window.scrollTo(0,Math.max(document.documentElement.scrollHeight,document.body.scrollHeight,document.documentElement.clientHeight));");

(or)

Actions actions = new Actions(driver);
actions.keyDown(Keys.CONTROL).sendKeys(Keys.END).perform();

Full scroll to bottom in slow motion:

for (int second = 0;; second++) {
        if(second >=60){
            break;
        }
            ((JavascriptExecutor) driver).executeScript("window.scrollBy(0,400)", ""); //y value '400' can be altered
            Thread.sleep(3000);
}

(or)

JavascriptExecutor jse = (JavascriptExecutor)driver;
for (int second = 0;; second++) {
        if(second >=60){
            break;
        }
            jse.executeScript("window.scrollBy(0,800)", ""); //y value '800' can be altered
            Thread.sleep(3000);
}

Scroll automatically to your WebElement:

Point hoverItem =driver.findElement(By.xpath("Value")).getLocation();
((JavascriptExecutor)driver).executeScript("return window.title;");    
Thread.sleep(6000);
((JavascriptExecutor)driver).executeScript("window.scrollBy(0,"+(hoverItem.getY())+");"); 
// Adjust your page view by making changes right over here (hoverItem.getY()-400)

(or)

((JavascriptExecutor)driver).executeScript("arguments[0].scrollIntoView();", driver.findElement(By.xpath("Value')]")));
(or)
WebElement element = driver.findElement(By.xpath("Value"));
Coordinates coordinate = ((Locatable)element).getCoordinates(); 
coordinate.onPage(); 
coordinate.inViewPort();