André L. S. Softwares Development, Technologies and Curiosities

Retrieving an Oracle cursor in Java

Many people come here looking for one way to retrieve cursors of Oracle procedures in Java. To them, I’ve here are a tutorial showing how to do this.

To retrieve the cursor you should declare him how a REF CURSOR in Package spec.

  --Creating the REF CURSOR type
  type g_cursor is ref cursor;

In both, spec and body, you need declare an out REF CURSOR variable in procedure signature, how cited above.

  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor);

The cursor must be opened in procedure’s body to return, this way:

open o_cursor for
          select car_id, company, model, color, hp, price
          from tbl_car
          where car_id = i_id;

The complete Package:

create or replace package PAC_CURSOR is
  --Creating REF CURSOR type
  type g_cursor is ref cursor;

  --Procedure that return the cursor
  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor); -- Our cursor

end PAC_CURSOR;
/

create or replace package body PAC_CURSOR is
  procedure PRO_RETURN_CARS(
    i_id     in     tbl_car.car_id%type,
    o_cursor in out g_cursor) is

       begin
        --Opening the cursor to return matched rows
        open o_cursor for
          select car_id, company, model, color, hp, price
          from tbl_car
          where car_id = i_id;

  end PRO_RETURN_CARS;

end PAC_CURSOR;

We have Oracle side ready, now we need create Java call

How the cursors are being returned by a procedure, we’ll used a java.sql.CallableStatement instance.

CallableStatement cs = conn.prepareCall("{call PAC_CURSOR.PRO_RETURN_CARS(?,?)}");

The registerOutParameter will obtain oracle.jdbc.OracleTypes.CURSOR type and return a java.sql.ResultSet instance. We can iterate the ResultSet like a common Iterator.
Each row column returned by SELECT will be represented how a map, using correspondent getter. For example, we will call getString(<column name>) method when value of column is a varchar, getDate(<column name>) when is a date and etc.

The complete code will be like this:

//Calling Oracle procedure
CallableStatement cs = conn.prepareCall("{call PAC_CURSOR.PRO_RETURN_CARS(?,?)}");

//Defining type of return
cs.registerOutParameter("o_cursor", OracleTypes.CURSOR);
cs.setLong("i_id", id);

cs.execute();//Running the call

//Retrieving the cursor as ResultSet
ResultSet rs = (ResultSet)cs.getObject("o_cursor");

//Iterating the returned rows
while(rs.next()){
	//Getting column values
	System.out.println("ID: " + rs.getLong("car_id"));
	System.out.println("Manufacturer: " + rs.getString("company"));
	System.out.println("Model: " + rs.getString("model"));
	System.out.println("Color: " + rs.getString("color"));
	System.out.println("HP: " + rs.getString("hp"));
	System.out.println("Price: " + rs.getFloat("price"));
}

In the end you will get any value returned in a SELECT clause.

See ya!