Java Applet在浏览器中不起作用-使用图像文件

Question

I have a java applet which demonstrates some filters. I have a predefined path for an example image and the user is able to choose an own picture.

I can't use new File because I am working in the browser and hav no access to the users storage. So I use a byte array to store my image data which was cropped and resized by using the library Thumbnailator:

public byte[] resize(String filepath) throws IOException{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();

        this.setBackground(Color.RED);
//      System.out.println("public File resize(String filepath)...");

        Thumbnails.of((new URL(filepath)))
        .size(256, 256)
        .outputQuality(1.0f)
        .outputFormat("jpg")
        .toOutputStream(outStream);

        byte[] bosArray = null; 
        bosArray = outStream.toByteArray();

        return bosArray;
    }

that is the call of resize() in my init():

try {
            if (ONLINE){
                String fname = FILENAME;
                if(getCodeBase()!=null)
                    fname = getCodeBase() + FILENAME;

                input = resize(fname);
            } 
            else {
                inputF = resize(new File(FILENAME));
            }

        } catch (IOException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

and FILENAME is defined as a field:

private static final String FILENAME = "mountains.png";

in another class ImagePanel I transfer the byte array into a BufferedImage:

public class ImagePanel extends JScrollPane {

private BufferedImage img;
private int width;
private int height;
private int[] histo;
private int[] normHisto; // normalized histogram
private int histogramHeight = 256;
private double variance;
private double expectation;

private int maxValueInHisto = 0;

/**
 * draw the image by using the stored BufferedImage
 */
public void paint(Graphics g) {
    g.drawImage(img, 0, 0, null);
}

.....

public ImagePanel(byte[] input) {

        try {
            //convert byte array back to BufferedImage
            InputStream in = new ByteArrayInputStream(input);
            img = ImageIO.read(in);

        } catch (IOException e) {
        }

        updateValues();
        this.setSize(width, height);
    } 

And everything works in the applet viewer of Eclipse but in the browser.. nothing happens. It loads the applet and show nothing even no error message.

If I comment everything out and leave only the init of the applet and setting a background color -> it works. So that means that my html code should be fine

<applet width="1000" height="1000" code="filterpackage.mainView.class" archive="Thumbnailator-0.3.10-all.jar"/>  

I tested it offline with Xampp and online in Chrome, Safari, Firefox but nothing happens, no error but no panel, no GUI.. nothing.

Do you know what is wrong? Or do you have a tip what I could try?

It would be great if someone can help me I spent so much time until now and I don't find the solution :(

Answer 1

if you run your applet from a local HDD the code like

getCodeBase() + FILENAME

definitely returns a local applet file path like a (in windows case)

file: C:/.../...

So file: protocol is not the http: protocol so that may cause the problem with your net image to download according to the said path... Moreover, you say you have unsigned applet...

As a simple way, you should place the applet to the Tomcat webapp folder and run it in this manner

http://localhost:8080/myappletpackage/applet.html

etc

If you have some additional question details do comment

Report that helps

Good luck