How to use database file within jar archive

Question

Hi. I'm quite new in Java programming, and I'm wondering if what I did makes sense or not.
In my applet I'm using a MS Access Database file, which is contained in the same Jar Archive like the Applet class file. I tried and tried to use this Database file directly but it wouldn't work. Than I read in some other forum that it is not possible to use the database file directly within the archive. First question: Is that true?
Than I desided to extract the DB file in the init() method of my applet to the default temporary foulder. When the program is closed I use the destroy() method to delete it again. Everything works well now. But is this the typical way this is done?
Thanks for help!

Answer 1

Hi,
here is the code which extracts the database file out of the jar archive (the same archive in which the class file is):
//get the user temporary folder
File TempFolder = new File(System.getProperty("java.io.tmpdir"));
//create (empty) db file
efile = new File(TempFolder, "steelSections.mdb");
// if database file is not yet extracted
if (!efile.exists()) {
//get an input stream for the database file
InputStream in = new BufferedInputStream(this.getClass().getClassLoader().getResourceAsStream(
"FaST/db/steelSections.mdb"));
//create an output stream for the db file on the file system
OutputStream out = new BufferedOutputStream(new FileOutputStream(efile));
//-Buffer to copy the data
byte[] buffer = new byte[2048]; //buffer to copy the binary
for (;;) {
int nBytes = in.read(buffer); //read data
if (nBytes <= 0)
break; //no more data to read
out.write(buffer, 0, nBytes); //write data
out.flush(); //close out and in streams
out.close();
in.close();
If you have the db file in an other jar archive file you need a referenze to the entry in the other jar archive. I'm not sure how to get this, but I'm sure you fill find a solution by searching in this forum...
Good luck!