File as Attachment in J2ME client

[lokesh jain]

hi all,
I have made a java web service. Which takes SQL query, Username and password of Database to connect to and the file name which i want to give to the created text file as parameters and it returns a text file. Now, I want to receive the same file ( stored at server side) on J2ME client side. If i make a normal Java web service client then I can get the file using DataHandler. However, I am not able to get the file as attachment using the DataHandler at J2ME client side. It said it does not recognize DataHandler, however I tried and the server side code returns the datahandler as byte[]. I tried to take the advantage and in J2ME client took the result as byte[]. But no use It is giving me Uncaught exception java/lang/NullPointerException. Can you please look into it. I am attaching the files, Server side code and the client side code and the files made as stub.
The client side code is here

  
package DataBaseConnection;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.*;

/**
 * @author Lokesh_Jain
 */
public class DataBaseMidlet extends MIDlet implements Runnable, CommandListener{

    private Form form;
    private Display display;
    private Command result,exit;
    private Alert alert;
    private TextField textf,textf2,textf3,textf4;
    String DataQuery = "";
    String UsrNam ="";
    String Pswrd = "";
    String FilNam = "";
    DBconService_Stub dbss;
    
    public DataBaseMidlet()
    {
        display = Display.getDisplay(this);
        result = new Command("Ok", Command.OK, 1);
        exit = new Command("Exit", Command.SCREEN, 1);
        textf = new TextField("Enter Query   :", "", 100, TextField.ANY);
//       textf.getString()
//        System.out.println("value of textf >>> "+ textf.getString());
        textf2 = new TextField("Enter UserName   :", "", 20, TextField.ANY);
        textf3 = new TextField("Enter Password   :", "", 20, TextField.ANY | TextField.PASSWORD);
        textf4 = new TextField("Enter File Name :  ", "", 30, TextField.ANY);
        form = new Form("Connecting to Database");
        form.append(textf);
        form.append(textf2);
        form.append(textf3);
        form.append(textf4);
        form.addCommand(result);
        form.addCommand(exit);
        form.setCommandListener(this);
    }

    public void DataBaseResult()
    {
          System.out.println("inside Database Result");
        DataQuery = textf.getString();
        UsrNam = textf2.getString();
        Pswrd = textf3.getString();
        FilNam = textf4.getString();
        new Thread(this).start();
      
//        String st = null;
////        String st1 = textf.getString();
//        System.out.println("value of SQL Query >>> "+SQLquery);
//        System.out.println("value of Username  >>> "+Uname);
//        System.out.println("value of Password >>> "+Pass);
//        
//        st = FinalResult(SQLquery,Uname,Pass);
//        
//        return st;
    }
    public void run(){
        byte[] st1 = null;
        try{
             dbss = new DBconService_Stub();
            System.out.println("Values passed to Stub  >> "+DataQuery+
                    ">>>>     "+UsrNam+" >>>>>>   "+Pswrd+ ">>>>>>    "+FilNam);
//         st1
           String str         =    dbss.DB(DataQuery, UsrNam, Pswrd,FilNam).toString();
         System.out.println("value of STr >>   "+str);  
         System.out.println("value of ST1 >>   "+st1);
         String st2 = st1.toString();
         System.out.print("Value of ST2 >> "+st2);
         form.append(st2);
         display.setCurrent(form);
//            st1 = dbss.DB(Sq, Un, Pa);
            
        }catch(Exception ex){
            Alert serviceAlert = new Alert("Service Problem", "Try it later", null, AlertType.ERROR);
            serviceAlert.setTimeout(Alert.FOREVER);
            display.setCurrent(alert, form);
            System.out.print("Inside Catch  "+ex);
        }
//        return st1;
    }

    public void startApp() {
        
//        String str = DataBaseResult();
        display.setCurrent(form);
    }

    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }

    public void commandAction(Command cmd, Displayable disply) {
        //throw new UnsupportedOperationException("Not supported yet.");
        String label = cmd.getLabel();
try{
        if(label.equals("Exit"))
        {
            destroyApp(false);
            notifyDestroyed();
        }else if(label.equals("Ok"))
        {
            DataBaseResult();
        }
    }catch(Exception ex)
    {
        System.out.print("inside the CommantAction Exception  "+ex);
    }
    }
}
  

The server side code is ::

  
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

package trc;

import java.io.*;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.jws.WebMethod;
import javax.jws.WebParam;
import javax.jws.WebService;
import javax.xml.bind.annotation.XmlMimeType;

/**
 *
 * @author Chetan_Saini
 */
@WebService()
public class DBcon {

    /**
     * Web service operation
     */
    @WebMethod(operationName = "DB")
    public 
            @XmlMimeType( "application/octet-stream" )
            DataHandler DB(@WebParam(name = "Query")
    String Query, @WebParam(name = "UserName")
    String UserName, @WebParam(name = "Password")
    String Password, @WebParam(name = "FileName")
    String FileName){
        DataHandler dh = null;
        File file = null;
        Writer writer = null;
        Connection conn = null;
        Statement stmt = null;
            ResultSet rs = null;
            ResultSetMetaData rsmd = null;
            String spaces = "          ";
            
        try{
//            String chemin = "D://LuckyDB.accdb";
            System.out.println("inside TrY");
             FileName = FileName.trim();
              System.out.println("after filename");
         /*    UserName = UserName.trim();
              System.out.println("after username");
             Password = Password.trim();
              System.out.println("after password");  */
             Query = Query.trim();
            String DriverName = "sun.jdbc.odbc.JdbcOdbcDriver";
            String DBUrl = "jdbc:odbc:LuckyDB";
            Class.forName(DriverName);
            System.out.println("before connection");
            conn = DriverManager.getConnection(DBUrl, UserName, Password);
            System.out.println("---connection object value is ---"+conn);
            stmt = conn.createStatement();
            System.out.print("The Query  ::    "+Query);
            rs = stmt.executeQuery(Query);
            rsmd = rs.getMetaData();
            System.out.println("Value of RSMD > "+rsmd);
            int iTemp = 0;
            String column = "";
            String row = "";
           
            System.out.print("The Filename   ::    "+FileName);
            file = new File("D:/"+FileName+".txt");
            writer = new BufferedWriter(new FileWriter(file));

            for(iTemp=1; iTemp<= rsmd.getColumnCount(); iTemp++)
            {
                column = rsmd.getColumnLabel(iTemp);
                column = column.toUpperCase();
                writer.write(column+spaces);
            }
            while(rs.next()){

                for(iTemp=1; iTemp<= rsmd.getColumnCount(); iTemp++){
                    row = rs.getString(iTemp);
                    writer.write(row+spaces);
                }
//				System.out.println("---Roll number---"+rs.getString("RollNo"));
////                System.out.println("Value of RS > "+rs.getString(2));
//				System.out.println("---Student name---"+rs.getString("StudentName"));
//                System.out.println("---Student Class---"+rs.getString("StudentClass"));
                
			}
            writer.close();
           file = new File("D:/"+FileName+".txt");
           dh = new DataHandler(new FileDataSource(file));
           conn.close();

        }catch(Exception ex){
            System.out.println("inside exception  "+ex);
        }
        //TODO write your implementation code here:
        return dh;
    }

}

  

Thanks in advance
Lokesh

[Aleksandar Babic]

If I understood you correctly, you want to download text file from server with your j2me client, and it should be response from java webservice.
Maybe this link would be helpful
http://www.java-samples.com/showtutorial.php?tutorialid=15
You can modify it to make proper ws request

[lokesh jain]

hi, you are right, we can do like that. However, I need to get the file as attachment to client side, not getting the Byte Array. Is this possible that, we get the text file and store it in RMS and then read it from RMS itself??

regards
Lokesh

[Aleksandar Babic]

You can store anything in RMS including objects (check Floggy framework)
I'm not sure you can get anything except byte array but you can deserialize it to something useful

Are you trying to send mail with attachment?
For reading attachment you may need some j2me mail api.