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I am trying to open an image file that is packaged in a .jar file using the default image viewer of the computer on which i run my program.

I have found numerous answers about how to access files that are packaged in a jar using InputStream but how can i open those files using that InputStream?

InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");

I can convert this into an Image, ImageIcon or a BufferedImage but how to i further open the image in the default image viewer?

My class name is 'Test' and the image i am trying to access is C:\Users\Pranav\Documents\NetBeansProjects\Test\src\test\DSC_6283.jpg

Any help would be appreciated.

Pranav
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2 Answers2

9

Pure java:

public static void main(String... args) throws IOException {
    InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");
    Path path = Files.createTempFile("DSC_6283", ".jpg");
    try (FileOutputStream out = new FileOutputStream(path.toFile())) {
        byte[] buffer = new byte[1024]; 
        int len; 
        while ((len = imageStream.read(buffer)) != -1) { 
            out.write(buffer, 0, len); 
        }
    } catch (Exception e) {
        // TODO: handle exception
    }
    Desktop.getDesktop().open(path.toFile());
}

Edit: 

        byte[] buffer = new byte[1024]; //allocate an array of bytes to use as a buffer. 1024 bytes in this case
        int len; //a variable to record the number of bytes actually read from the stream each loop
        while ((len = imageStream.read(buffer)) != -1) { //InputStream.read(byte[]) reads bytes from the stream and places them into the buffer. It returns the number of bytes placed into the buffer, or -1 if there is nothing more to read. We store that result in len, and evaluate if we should stop looping (ie if the return is -1)
            out.write(buffer, 0, len); //write to the output file, from the buffer, starting at position 0, through the number of bytes read

Note, this is boilerplate. I stole this version from Easy way to write contents of a Java InputStream to an OutputStream

Community
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Andreas
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  • Thanks a lot!:) Works perfectly! Could you please explain how these lines work- `byte[] buffer = new byte[1024];` `int len;` `while ((len = imageStream.read(buffer)) != -1) {` `out.write(buffer, 0, len);` `}` – Pranav Sep 06 '14 at 02:17
  • @Pranav added comments – Andreas Sep 08 '14 at 16:02
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  1. Save the image locally (ex. c:\my_image.jpg), which is not in the .jar file
  2. Use Runtime.getRuntime().exec("cmd your_command_here_to_open_image"); here is a link for cmd command on windows: http://www.sevenforums.com/software/180378-where-windows-photo-viewer-default-location.html
russu
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