how to get the path of server's folder inside Java program (J2EE + JSTL)

Question

I wanted to read contents of Excel files in my web-based project (J2EE-JSP+Servlets) which are located inside the web server's folder.

I have made a java file, which i will call through a JSP page using JSTL library, but I need to get the path of the Excel sheet in the Java file, so I can read the contents.

How can I get the path to the current Java file and so the Excel file?

Also, I will be reading the contents of the Excel file through POI library. I was able to do this in J2SE development, but is it possible here?

POIFSFileSystem fs = null;
    try {
        fs = new POIFSFileSystem(new FileInputStream("**some path here of sheet**"));
    } catch (FileNotFoundException ex) {
        ex.printStackTrace();
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    HSSFWorkbook wb = null;
    try {
        wb = new HSSFWorkbook(fs);
    } catch (IOException ex) {
        ex.printStackTrace();
    }
    HSSFSheet sheet = wb.getSheetAt(0);
    HSSFRow row;
    HSSFCell cell1,cell2,cell3; 

    int rows; // No of rows, stores the no. of rows for an excel sheet
    int cols; // No of columns, stores the no. of columns for an excel sheet

    rows = sheet.getPhysicalNumberOfRows();
    cols = 5;

    for(int r = 0; r < rows; r++) {
        row = sheet.getRow(r);

        if(row != null) {
            cell1 = row.getCell(1);
            cell2 = row.getCell(2);
            cell3 = row.getCell(4);

            //System.out.println(cell1.getStringCellValue()+" "+cell2.getStringCellValue()+" "+cell3.getStringCellValue());                
        }
    }
}

Answer 1

You can ask servlet context to translate relative to real path:

context.getRealPath("/");

If you java class is servlet, you can probably do something like

getServletConfig().getServletContext();

otherwise, jsp page is a servlet, so you can pass it from there.

Finally, you can pick it up once when you start your app:

public class AppStartup implements ServletContextListener {

    public void contextDestroyed(ServletContextEvent event) {
    }

    public void contextInitialized(ServletContextEvent event) {
        ServletContext context = event.getServletContext();
        // remember it in some static class for future use
    }
}

Having said all this, it's probably better to make a servlet that has his servlet context, resolve path, and call your class with resolved path to a file, then finally forward request to a jsp page to display results.