java 中调用oracle中返回游标类型的存储过程

public String getreducestate(String reduceid) {
String temp = "";
StringBuffer buffer = new StringBuffer();
Session session = getSession();
ResultSet rs = null;
try { 
      Connection conn = session.connection(); 
      CallableStatement call = null; 
      call = conn.prepareCall("{call PK_TASK_QUERY.PRO_TASK_PERCENT_QRUERY(?,?)}"); 
      call.setString(1, reduceid); //传入参数
      call.registerOutParameter(2, oracle.jdbc.OracleTypes.CURSOR);//返回参数
      call.execute();
      rs = (ResultSet) call.getObject(2);
      while (rs.next()) {
      buffer.append(rs.getString(1) + ","); // 子任务id
      buffer.append(rs.getDouble(2) + ","); // 累加的百分比
      buffer.append(rs.getDate(3) + "#"); // 时间
   }
    call.close();
} catch (Exception ce) {
  ce.printStackTrace();
}
temp = buffer.toString();
return temp;
}