import java.sql.*;

class DbmsOutput {

	public DbmsOutput(Connection conn) throws SQLException {
		enable_stmt = conn.prepareCall("begin dbms_output.enable(:1); end;");
		disable_stmt = conn.prepareCall("begin dbms_output.disable; end;");

		show_stmt = conn
				.prepareCall("declare "
						+ "    l_line varchar2(4000); " //set the buffer size to max
						+ "    l_done number; "
						+ "    l_buffer long; "
						+ "begin "
						+ "  loop "
						+ "    exit when length(l_buffer)+255 > :maxbytes OR l_done = 1; "
						+ "    dbms_output.get_line( l_line, l_done ); "
						+ "    l_buffer := l_buffer || l_line || chr(10); "
						+ "  end loop; " + " :done := l_done; "
						+ " :buffer := l_buffer; " + "end;");
	}

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

public class TestOracle {

	/**
	 * @param args
	 */
	public static void main(String args[]) throws SQLException {
		DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());

		Connection conn = DriverManager.getConnection(
				"jdbc:oracle:thin:@localhost:1521:orcl", "username", "password");
		conn.setAutoCommit(false);

		Statement stmt = conn.createStatement();

		DbmsOutput dbmsOutput = new DbmsOutput(conn);
		dbmsOutput.enable(1000000);

		stmt.execute("begin p1.test_output(400);p1.test_output(400);p1.test_output(400);  end;");
		stmt.close();

		dbmsOutput.show();
		dbmsOutput.close();

		conn.close();
	}

}

CREATE OR REPLACE
PACKAGE BODY P1
AS
PROCEDURE test_output(
  times   IN NUMBER
  )
AS
  str varchar2(4000);
BEGIN
  for x in 1..times loop
    str := str || ' hello' || x;    
  end loop;
  dbms_output.put_line('result:' || str);  
END test_output;
END P1;