How do you get values from all columns using ResultSet.getBinaryStream() in jdbc?

Harish Vangavolu picture Harish Vangavolu · Jul 24, 2014 · Viewed 62.9k times · Source

How do I to write an entire table to a flat file (text file) using jdbc? So far I've attempted the following:

Statement statement = connection.createStatement();
   ResultSet result = statement.executeQuery("SELECT * FROM tablename");
   BufferedInputStream buffer;
   FileOutputStream out = new FileOutputStream("flatfile.txt");
   while(result.next() )
   {
      buffer =  new BufferedInputStream(result.getBinaryStream("????") );
      byte[] buf = new byte[4 * 1024]; //4K buffer
      int len;
      while( (len = buffer.read(buf, 0, buf.length) ) != -1 )
      {
          out.write(buf, 0, len );
      }
   }
   out.close();

"????" is just my placeholder. I am stuck on what to pass in as an argument.

Answer

Adarsh picture Adarsh · Jul 25, 2014

You can get all the column names and the entire data from your table using the code below. writeToFile method will contain the logic to writing to file (if that was not obvious enough :) )

    ResultSetMetaData metadata = rs.getMetaData();
    int columnCount = metadata.getColumnCount();    
    for (int i = 1; i <= columnCount; i++) {
        writeToFile(metadata.getColumnName(i) + ", ");      
    }
    System.out.println();
    while (rs.next()) {
        String row = "";
        for (int i = 1; i <= columnCount; i++) {
            row += rs.getString(i) + ", ";          
        }
        System.out.println();
        writeToFile(row);

    }