How to store url path?

Image is stored in physical directory like this String file = "C:/xampp/htdocs/jobqueen/" + username + createTimeStampStr() + ".PNG"; this physical directory is working fine 

but I want store in url path like this String file = "http://www.queen.com/website/screenshots/" + username + createTimeStampStr() + ".PNG"; 

this my program 
public class Image{ 
.............................. 

public static void writeImage(BufferedImage img, String fileLocation, 
String extension) { 
try { 
BufferedImage bi = img; 
File outputfile = new File(fileLocation); 
ImageIO.write(bi, extension, outputfile); 
} catch (IOException e) { 
e.printStackTrace(); 
} 
} 
public static String createTimeStampStr() throws Exception { 
................... 
} 
public void randomImage(String uname) throws Exception { 
..................... 

Robot robot = new Robot(); 
BufferedImage bi = robot.createScreenCapture(new Rectangle(1000,900)); 

String file = "http://www.queen.com/website/screenshots/" + username + createTimeStampStr() + ".PNG"; 
writeImage( bi, file, "PNG"); 
} 
} 


when I run this program i am getting this error 



java.io.FileNotFoundException: http:\www.queen.com\website\screenshots\amit1220120625_110414.PNG (The filename, directory name, or volume label syntax is incorrect) 
at java.io.RandomAccessFile.open(Native Method) 
at java.io.RandomAccessFile.<init>(RandomAccessFile.java:212) 
at javax.imageio.stream.FileImageOutputStream.<init>(FileImageOutputStream.java:53) 
at com.sun.imageio.spi.FileImageOutputStreamSpi.createOutputStreamInstance(FileImageOutputStreamSpi.java:37) 
at javax.imageio.ImageIO.createImageOutputStream(ImageIO.java:393) 
at javax.imageio.ImageIO.write(ImageIO.java:1514) 
at Image.writeImage(Image.java:29) 
at Image.randomImage(Image.java:71) 
at Image.run(Image.java:120) 
at java.lang.Thread.run(Thread.java:619) 
java.lang.NullPointerException 
at javax.imageio.ImageIO.write(ImageIO.java:1523) 
at Image.writeImage(Image.java:29) 
at Image.randomImage(Image.java:71) 
at Image.run(Image.java:120) 
at java.lang.Thread.run(Thread.java:619) 


plz need help