loadjava -v -r user_name/pass@sid -r jxl.jar

create or replace and compile java source named createReport as

import jxl.Workbook;
import jxl.write.Label;
import jxl.write.WritableSheet;
import jxl.write.WritableWorkbook;
import java.io.File;

public class createReport {
  private static String filePath;
  private static String fileName;

//for excel writing  
  private static WritableSheet sheet;
  private static Label label;
  private static WritableWorkbook workbook;  
  
  
  private static String runReportByRows() {
    try{
      int fileIndex = 0;
      workbook = Workbook.createWorkbook(new File(filePath+fileName+"_"+fileIndex+".xls"));
      sheet = workbook.createSheet("Sheet"+fileIndex, 0);

      label = new Label(1, 1 ,"TEST");
      sheet.addCell(label);

      workbook.write();
      workbook.close();
      return "OK";
    } catch (Exception e){
      return "Error: "+ e.toString();
    } 
  }
  
  public static String createReport(String filePath1,String fileName1){
    filePath = filePath1;
    fileName = fileName1;

    String selectStatement = "";
    try {
      String returnedString = runReportByRows();  
      return returnedString;
    } catch (Exception e) {
      return "Error: "+ e.toString();
    }
  }
}
/

create or replace function Func_createReport(filePath String, fileName String) return varchar2
is language java name
'createReport.createReport(java.lang.String,java.lang.String) return java.lang.String';
/

BEGIN
  DBMS_JAVA.GRANT_PERMISSION ( 'user_name', 'java.io.FilePermission','C:\temp\', 'read,write' );
  COMMIT;
END;
/

declare
  str varchar2(1000);
begin
  str := odb.func_createReport('c:/temp/','test');
  dbms_output.put_line(str);
end;

workbook.write();