Relative path in JLabel HTML

StackOverflow https://stackoverflow.com/questions/1593742

Question

I am trying to make JLabel show an html which is referencing an image using a relative path. But I cannot make JLabel locate the image. It works fine when I am using absolute path.

I have tried running the program from the command line or from eclipse and add dialog to show me where is the current working directory but for avail. I have therefor came to the conclusion that the image is not searched in the current directory - which brings me to the point. where is the image looked for?

here is a test code that show what I am doing:

import javax.swing.*;

public class HTMLLabel extends JFrame {
    public HTMLLabel() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JOptionPane.showMessageDialog( this, 
                System.getProperty("user.dir"));

         String html = "<html>\n" +
        "   <body>\n" +
        "       <div style=\"text-align: center;\">\n" + 
        "           <img src=\"file://s.png\">\n"+
        "       </div>\n"+
        "   </body>\n"+
        "</html>";

         JLabel label = new JLabel(html);
         add(label);

         pack();
         setVisible(true);
    } 

    public static void main(String[] args) {
         new HTMLLabel();
    }
}
Was it helpful?

Solution

Use this function to prepare the html text for the JLabel to display images relative to the package of a class.

public static String prepareHtmlToJLabelText(Class relativeClass, String html) {
    Pattern p = Pattern.compile("src=['\"](.*?)['\"]");
    Matcher m = p.matcher(html);
    while (m.find()) {
        html = html.replace(m.group(), "src='" + relativeClass.getResource(m.group(1)) + "'");
    }
    return html;
}

The function replace the content of the "src" attribute to make it relative to the provider class.

Example:

jLabel.setText(prepareHtmlToJLabelText(this.getClass(), "<html><div style='text-align: center;'><img src='imageA.png'></div>Bla bla bla...<div style='text-align: center;'><img src='imageB.png'></div>"));

Anyway for a real html support use JEditorPane.

OTHER TIPS

I see two variants:

I don't know why but for me this works

"                       <img src=\"file:s.png\">\n"+

assuming that s.png is in current working directory.

Another variant that seems more appropriate for me is:

URL url = HTMLLabel.class.getResource( "/s.png" );
  String html = "<html>\n" +
    "       <body>\n" +
    "               <div style=\"text-align: center;\">\n" + 
    "                       <img src=\""+url+"\">\n"+
    "               </div>\n"+
    "       </body>\n"+
    "</html>";

Why are you even doing it like this? Just use this JLabel(Icon image) constructor

JLabel label = new JLabel(createImageIcon("s.png","description"));

protected ImageIcon createImageIcon(String path, String description) {
  java.net.URL imgURL = getClass().getResource(path);
  if (imgURL != null) {
    return new ImageIcon(imgURL, description);
  } else {
    System.err.println("Couldn't find file: " + path);
    return null;
  }
}

Or if you insist on the html variant.

btw The file protocol uses 3 slashes (file://s.png is invalid) and file:///s.png would mean C:\s.png. If the image resides in the starting directory you could use.

String path = System.getProperty("user.dir");
String html =
  "<html>\n" +
     "<body>\n" +
        "<div style=\"text-align: center;\">\n" +
          "<img src=\"file:///"+path+"/s.png\">\n"+
        "</div>\n"+
     "</body>\n"+
  "</html>";

But I make no guarantees about the 2nd solution.

i just replaced your 

<img src=\"file://s.png\">\n"
//with
<img src=\"file:///s.png\">\n"+

and that solved the problem

NOTE: i placed the s.png file in the src/java folder

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