a file in your Jar, How do I access it in code?

[Rooks Forgenal]

I am running a Jar and the very first thing it needs to do is import (if I may use that term?) this script file as a 'File' in code. The problem is the script file is located INSIDE the Jar. Thus, a direct path (absolute) will not work. I think is has something to do with:

this.getClass().getResource("ScriptFile").getFile()

The problem is, it returns a URL. I am missing the connect. How do I use the URL to import the file into a File variable in the code from my Jar?

[Sebastian Janisch]

i think it should look like this..

if your jar has the following structure
/folder1/file.txt

then you should be able to access it like this:

 

InputStream is = this.getClass().getResourceAsStream("/folder1/file.txt");
BufferedReader buf = new BufferedReader(new InputStreamReader(is)));

String s = "";
StringBuilder sb = new StringBuilder();
while((s = buf.readLine()) != null) {
    sb.append(s);
}

   

[Rooks Forgenal]

I need the file that is within the Jar to be brought in as a 'File' and not a string. Like this:

File file = new File(give me the file inside the Jar called XYZ);

Wait... your string is named 's' right? Could I do this?

File file = new File(s);

[Sebastian Janisch]

try this... i am not sure whether or not this is working

File f = new File(this.getClas().getResourceAsStream().getFile());

getFile() returns the fully qualified path + file as a string

[Rob Spoor]

A resouce is not necessarily a file. It only is a file if it's not in a JAR / ZIP file.

If you really need it to be a file, the only safe way is create a temporary file, and copy the resource's contents to it. Check out File.createTempFile.

[Rooks Forgenal]

Ok, I have this code below. I believe it is of sound reasoning but it does not work. Basically, I still do not have access to the file "test_method.rb" inside the jar. Would someone read the code below and point out my error in thinking? Thank you in advance.

try {
      String tmpDir = new java.io.File(".").getCanonicalPath();
      bw = new BufferedWriter(new FileWriter(tmpDir + "\\test_method.rb"));

      InputStream is = this.getClass().getResourceAsStream("test_method.rb");
      BufferedReader br = new BufferedReader(new InputStreamReader(is));
      while (br.ready()) {
        bw.write(br.readLine());
      }

      file = new File(tmpDir + "\\test_method.rb");
      jTextPane1.setText(file.getAbsolutePath());
      if (file.isFile()) {
        JRuby = new Stream_Listeners(file);
      } else {
        jTextPane1.setText("Not a valid file");
      }
    } catch (Exception ex) {
      jTextPane1.setText(jTextPane1.getText() + "\n" + ex.toString());
    }

Brightmatter

[Rob Spoor]

http://faq.javaranch.com/java/AvailableDoesntDoWhatYouThinkItDoes

In short, change the copying code:

bw = new BufferedWriter(new FileWriter(tmpDir + "\\test_method.rb"));   
  
InputStream is = this.getClass().getResourceAsStream("test_method.rb");   
BufferedReader br = new BufferedReader(new InputStreamReader(is));   
String line;
while ((line = br.readLine()) != null) {
    bw.write(line);
    bw.newLine();
}

Note that I have used bw.newLine() - br.readLine() strips off the line separators (line breaks) so you'll need to readd them.

Also, the call to getCanonicalPath is not really necessary. It will still point to the same folder, which is the current one. Also, the following is a better way of constructing a File in a specific folder:

file = new File(tmpDir, "test_method.rb");

Also, move this statement to before you create your BufferedWriter, then use it there as well:

file = new File(tmpDir, "test_method.rb");
bw = new BufferedWriter(new FileWriter(file));

Finally, keep in mind that BufferedReader and BufferedWriter are for text files. If test_method.rb is a binary file, use BufferedInputStream and BufferedOutputStream instead.

[Ernest Friedman-Hill]

There are several problems, all fixable. First, you're not closing the BufferedWriter, so likely it contains incomplete output (or no output.) Close it after writing to it.

Second, you're reading by lines, and then writing the lines into the new file without newlines between them. That will affect your Ruby syntax!

Third, this is a lot of work:

String tmpDir = new java.io.File(".").getCanonicalPath();
bw = new BufferedWriter(new FileWriter(tmpDir + "\\test_method.rb"));

when this does exactly the same thing:

bw = new BufferedWriter(new FileWriter("test_method.rb"));

Fourth, you might consider not using Readers and Writers, but rather Streams. It would save you dealing with the newline problem. Just take the inputstream from the URL, and open a FileOutputStream, allocate a byte[] for a buffer, and loop:

byte[] buffer = new byte[1024];
int c;
while ((c = in.read(buffer) != -1)
    out.write(buffer, 0, c);
out.close();
in.close();

[ Edit: Rob beat me to it ]

[Rob Spoor]

Ernest Friedman-Hill wrote:[ Edit: Rob beat me to it ]

I tend to do that a lot. Just ask Campbell

[Rooks Forgenal]

OH!! It works! It really works! I even used a temporary file as suggested above. I don't know why but it is not very temporary (i.e. it does not delete on exit as advertised).

I can't believe how much help I get from this one forum and none of the others. It is really night and day difference.

try {
      file = File.createTempFile("tempfile", ".txt");
      BufferedWriter bw = new BufferedWriter(new FileWriter(file));

      //I found this in the available methods... Looks cool but not deleting when GUI is closed.  I assume I am using it wrong.
      file.deleteOnExit();

      InputStream is = this.getClass().getResourceAsStream("test_method.rb");
      BufferedReader br = new BufferedReader(new InputStreamReader(is));
      String line;
      while ((line = br.readLine()) != null) {
        bw.write(line);
        bw.newLine();
      }
      bw.close();
      br.close();

      jTextPane1.setText(file.getAbsolutePath());
      if (file.isFile()) {
        JRuby = new Stream_Listeners(file);
      } else {
        jTextPane1.setText("Not a valid file");
      }
    } catch (Exception ex) {
      jTextPane1.setText(jTextPane1.getText() + "\n" + ex.toString());
    }

[Rob Spoor]

jake benn wrote:I don't know why but it is not very temporary (i.e. it does not delete on exit as advertised).

Usually a file deletion does not work because the file is still in use. It's not caused bw because you close that. Well, unless you get an IOException during copying. That's why a try-finally block is usually better:

try {
    file = File.createTempFile("tempfile", ".txt");

    //I found this in the available methods... Looks cool but not deleting when GUI is closed.  I assume I am using it wrong.
    file.deleteOnExit();

    BufferedWriter bw = new BufferedWriter(new FileWriter(file));
    try
    {
        InputStream is = this.getClass().getResourceAsStream("test_method.rb");
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        try
        {
            String line;
            while ((line = br.readLine()) != null) {
                bw.write(line);
                bw.newLine();
            }
        }
        finally
        {
            br.close();
        }
    }
    finally
    {
        bw.close();
    }

    jTextPane1.setText(file.getAbsolutePath());
    if (file.isFile()) {
        JRuby = new Stream_Listeners(file);
    } else {
        jTextPane1.setText("Not a valid file");
    }
} catch (Exception ex) {
    jTextPane1.setText(jTextPane1.getText() + "\n" + ex.toString());
}

Now I see that you're creating something called Stream_Listeners around the temporary file. Is that perhaps keeping a stream, reader or writer open?

[Rooks Forgenal]

Try - Finally... I have never heard of that... I feel like I have learned 15 new things today. Awesome! Thanks guys... or maybe gals?

[Rooks Forgenal]

Rob Prime wrote:
Now I see that you're creating something called Stream_Listeners around the temporary file. Is that perhaps keeping a stream, reader or writer open?

You are exactly right. Right on the nose my friend. That is just plain spooky that you knew that. I am going to step away now before you get my credit card numbers.

[Rob Spoor]

Too late. You won't mind that new laptop I bought with it, do you?

But seriously, it was just logical. file is a local variable. That means that any streams opened using it must be opened by this method, or a method / constructor called by this method. Since you close all streams opened in this method, and the JTextPane.setText methods don't open streams, there was just one possibility.

jake benn wrote:Try - Finally... I have never heard of that...

Try reading this for a second.

[Campbell Ritchie]

Rob Prime wrote:

Ernest Friedman-Hill wrote:[ Edit: Rob beat me to it ]

I tend to do that a lot. Just ask Campbell

Yes, it's true.