Open "byte array document" from a Java applet

Question

I've a signed applet that retrieves a PDF document from a web service, then stores it on a temp folder, and opens it on Adobe Reader. I would like to avoid storing the file locally, but I really don't know how to achieve it (I'm a newbie with Java applets).

If it were a web application (i.e. a simple servlet), I could just write the PDF content over the ServletResponse; then the browser would store it on its temporary folder, and open it with Adobe Reader (or whatever application is associated with the MIME type).

Is there a similar way to do this... on a Java applet?

This is my code so far:

public class MyListener implements ActionListener {
    public void actionPerformed(ActionEvent event) {
        // Retrieve the document contents
        byte[] content = webService.getPdfDocument(...);

        // Write to file
        File f = new File("my-document-filename.pdf");
        FileOutputStream fos = new FileOutputStream(f);
        fos.write(content);
        fos.close();

        // Open the file
        Desktop.getDesktop().open(new File("my-document-filename.pdf"));
    }
}

Any alternative to Desktop.open(File), allowing me to pass a byte[] instead of a File?

One way or another, the temp file will need to be created. I'm not sure what's wrong with Desktop.open. It's a perfectly valid way of doing things. — Aleks G
– Aleks G, Commented Jul 23, 2012 at 9:50
+1. I don't think you can avoid the temporary file, but maybe there is a way to have it managed by the browser (so that it gets cleaned up when done). — Thilo
– Thilo, Commented Jul 23, 2012 at 9:51
It's ok to create the temp file, as long as it's managed by the browser, just like it would be with the ServletResponse example. What I'd like to avoid is creating several PDF files "somewhere" in the user's local drive (i.e. C:/temp/a-document.pdf, C:/temp/another-one.pdf, etc) — AJPerez
– AJPerez, Commented Jul 23, 2012 at 10:40

dacwe · Accepted Answer · 2012-07-23 11:22:10Z

2

Adobe reader can handle URL:s, so it could be a way forward to create a temporary (?) URL for the document.
Otherwise you can create a temporary file use File.createTempFile, from the API:
Creates a new empty file in the specified directory, using the given prefix and suffix strings to generate its name. If this method returns successfully then it is guaranteed that:
1. The file denoted by the returned abstract pathname did not exist before this method was invoked, and
2. Neither this method nor any of its variants will return the same abstract pathname again in the current invocation of the virtual machine.
This method provides only part of a temporary-file facility. To arrange for a file created by this method to be deleted automatically, use the deleteOnExit() method.
So in your case, instead of creating a new file yourself you can use this method:
```
File f = File.createTempFile("tmp", ".pdf");
f.deleteOnExit(); // deletes the file on exit
...
```

edited Jul 23, 2012 at 11:22

answered Jul 23, 2012 at 10:53

dacwe

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3 Comments

AJPerez Over a year ago

Not exactly what I was looking for... but it might solve the problem. I'll give it a try. Thanks!

dacwe Over a year ago

Updated answer with another option. But the temporary file is not that bad.

AJPerez Over a year ago

The second option is not applicable in my case: I can't store the file server-side, so I can't open it with a URL. Anyway, your first option was already good enough :)

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