Remove boilerplate from db code

Question

It seems that every time I want to perform a db query, I have to write the following:

Connection conn = null;
Statement stmt = null;
ResultSet rset = null;

         


        

Answer 1

Make a helper method?

public class DBHelper
{
    public static Object run(string sql, List params, ResultHandler rhandler)
    {
        Connection conn = null;
        Statement stmt = null;
        ResultSet rset = null;

        try {
            conn = dataSource.getConnection();
            stmt = conn.prepareStatement(sql);
            int i = 0;
            for(Object p in params)
            {
                stmt.setObject(++i, p);
            }
            rset = stmt.executeQuery();
            return rhandler.handle(rset);
        } finally {
                try { rset.close(); } catch(Exception e) { }
                try { stmt.close(); } catch(Exception e) { }
                try { conn.close(); } catch(Exception e) { }
        }
    }
}

public interface ResultHandler
{
    public Object handle(ResultSet)
}

public class Test
{
    public static void main(String[] args)
    {
        String s = (String)DBHelper.run("select * from mytable where col = ?",
                Arrays.asList({"foo"}), 
                new ResultHandler
                {
                    public Object handle(ResultSet r)
                    {
                        r.first();
                        return r.getString("col2");
                    }
                }();
    }
}