Question

I’m trying to save a Java project in Eclipse as a jar file.

As I’m working with an Access database and I should export everything, I decided to include the database file in the same folder as Main.class and SingletonConnection.class (which is the class that manages the connection with the database).

So the code is:

private SingletonConnection()throws ConnessioneException{

    idConnection = "root";
    passConnection = "";

    String slash="\\";
    String path=this.getClass().getResource("").getPath().replaceFirst("^.*:", "").replaceFirst("!.*$", "").replace("/", slash.concat("\\"));

    System.out.println("path è "+path);

    driverConnection = "sun.jdbc.odbc.JdbcOdbcDriver";
    stringConnection = "jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ=C:"+path+"eventi.mdb";


    try {
        Class.forName(driverConnection);
        conn = DriverManager.getConnection(stringConnection,idConnection,passConnection);
    } catch (Exception e) {
        e.printStackTrace();
        throw new ConnessioneException();
    }
}

public static Connection getInstance()throws ConnessioneException{
    if(conn==null)
        new SingletonConnection();

    return conn; 
}

In Eclipse everything is ok. The project works and no exceptions, but when I try to export the project as a Runnable Jar File or a Jar File it always returns ConnessioneException =null so the connection to the db fails.

Exception is given in the method getInstance, line “new SingletonConnection()”

I need to run that program on other PCs, so I need to solve that. I cannot continue using Eclipse.

Answer 1

SOLVED : maybe it can be useful for someone:

 ***   import org.apache.commons.io.IOUtils; !!  (package: commons-io-2.1.jar)

    idConnection = "root";
    passConnection = "";

    String slash="\\";
    String path=null;

    String temp=System.getProperty("java.io.tmpdir");
    if ( !(temp.endsWith("/") || temp.endsWith("\\")) )
           temp = temp + System.getProperty("file.separator");
    File tempDir = new File(temp);
    File temporaryFile = new File(tempDir, "templateCopy.mdw");
    InputStream templateStream = getClass().getResourceAsStream("eventi.mdw");
    try {
        IOUtils.copy(templateStream, new FileOutputStream(temporaryFile));

    } catch (FileNotFoundException e1) {
        e1.printStackTrace();
        //Dialog d1=new Dialog("filenotfound");
    } catch (IOException e1) {
        e1.printStackTrace();
        //Dialog d2=new Dialog("io");
    }catch (Exception e1){
        //Dialog d3=new Dialog("general");
    }

    path = temporaryFile.getAbsolutePath();

    driverConnection = "sun.jdbc.odbc.JdbcOdbcDriver";
    stringConnection = "jdbc:odbc:driver={Microsoft Access Driver (*.mdb)};DBQ="+path;


    try {
        Class.forName(driverConnection);
        conn = DriverManager.getConnection(stringConnection,idConnection,passConnection);
    } catch (Exception e) {
        e.printStackTrace();
        throw new ConnessioneException(e.getStackTrace());
    }