Load image from a filepath via BufferedImage

To read an .jpg file from non-relative path you could use this:

BufferedImage img = null;

try 
{
    img = ImageIO.read(new File("C:/ImageTest/pic2.jpg")); // eventually C:\\ImageTest\\pic2.jpg
} 
catch (IOException e) 
{
    e.printStackTrace();
}

I do not have any Java environment at the moment, so hope it works and is written correctly.

getResource & getResourceAsStream do not work with file paths, but paths relative the code base. If the code base is C: then a relative path that would locate the resource is /ImageTest/pic2.jpg.

..difference between load file by FileInputStream and getResourceAsStream?

One major difference is that the getResource.. will work with a resource inside a Jar, which is no longer a File. Therefore FileInputStream cannot be used to access such a resource.