displaying image from database

[Ranga Medagoda]

import java.sql.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class displayserv extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String connectionURL = "jdbc:postgresql://localhost/ranga";
        PrintWriter out = response.getWriter();
        //response.setContentType("text");
        //response.setContentType("image/gif");
        java.sql.Connection con = null;
        Statement st1;
        try {
            Class.forName("org.postgresql.Driver").newInstance();
            con = DriverManager.getConnection(connectionURL, "postgres", "xxxx");
            st1 = con.createStatement();
            PreparedStatement ps = con.prepareStatement("SELECT img FROM tester.image WHERE id=?");
            ps.setString(1, "aa");
            ResultSet rs = ps.executeQuery();

            String imgLen = "";
            while (rs.next()) {
                imgLen = rs.getString(1);
                System.out.println(imgLen.length());
                int len = imgLen.length();
                byte[] rb = new byte[len];
                InputStream readImg = rs.getBinaryStream(1);
                int index = readImg.read(rb, 0, len);
                out.println("index----------------" + index);
                response.reset();
                response.setContentType("image/gif");
                response.getOutputStream().write(rb, 0, len);
                response.getOutputStream().flush();

            }
            rs.close();

            ps.close();
        } catch (Exception e) {
        //out.println(e);
        }
    }
}

have written this code for displaying a image stored in the database but when i run the code it says
The image “http://localhost:8080/WebApplication8/displayserv” cannot be displayed, because it contains errors.

I would be pleased if someone could help ,,,

[Ulf Dittmer]

It looks like you're trying to return several images in a single HTTP response; that doesn't work: 1 response = 1 image.

Delete the call to response.getWriter(); you can only call getWriter() or getOutputStream, not both.

You should also make sure that index == len; although that's likely to be the case, it's by no means guaranteed. You may have to call readImg.read in a loop to get all the bytes.

[Ranga Medagoda]

import java.sql.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class displayserv extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String connectionURL = "jdbc:postgresql://localhost/ranga";


        response.setContentType("image/gif");
        java.sql.Connection con = null;
        //Statement st1;
        try {
            Class.forName("org.postgresql.Driver").newInstance();
            con = DriverManager.getConnection(connectionURL, "postgres", "spiderman");
            //st1 = con.createStatement();
            PreparedStatement ps = con.prepareStatement("SELECT img FROM tester.image WHERE id=?");
            response.setContentType("text");
            ps.setString(1, "aa");
            ResultSet rs = ps.executeQuery();

            String imgLen = "";
            int read = 0;
            while (rs.next()) {

                imgLen = rs.getString(1);
                int len = imgLen.length();
                byte[] rb = new byte[len];
                InputStream readImg = rs.getBinaryStream(1);

                response.setContentType("image/gif");
                OutputStream os = response.getOutputStream();

                while ((read = readImg.read(rb)) != -1) {
                    os.write(rb, 0, len);
                }
                os.flush();
                os.close();
            }
            rs.close();

            ps.close();
        } catch (Exception e) {

        }
    }
}

Thank you very much for your kind help,,, I changed the code according to your comment but still getting the same error
Is there any problem with content type,, I have a saved image (a gif) in the database (database is psql and data type used there is bytea) there is only one image for that id 'aa'

Thanks again for your help,,,

[Ulf Dittmer]

For starters, drop the habit of putting QUOTE tags around your posts; as their name implies, they're for quoting something, not for new content.

Your code is confusing. You're retrieving a single attribute from the DB which you first treat as a string, and then as binary data. But it can only be one, not both - which one is it?

Make sure exactly as many bytes are streamed as there are in the image.

You can also use an HTTP monitor to look at what gets sent down the wire.

Lastly, " } catch (Exception e) { }" is a REALLY bad idea; how will you if there are problems?

[Ranga Medagoda]

import java.sql.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class displayserv extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String connectionURL = "jdbc:postgresql://localhost/ranga";
        java.sql.Connection con = null;
        response.setContentType("image/gif");

        try {
            Class.forName("org.postgresql.Driver").newInstance();
            con = DriverManager.getConnection(connectionURL, "postgres", "XXXXX");
            PreparedStatement ps = con.prepareStatement("SELECT img FROM tester.image WHERE id='aa'");
            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                byte[] rb = new byte[3000];
                int read = 0;
                InputStream readImg = rs.getBinaryStream(1);
                OutputStream os = response.getOutputStream();

                while ((read = readImg.read(rb)) != -1) {
                    os.write(rb,0,read);
                    
                }
                    os.flush();
                    os.close();
            }
            rs.close();
            ps.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Thank you for your help again and sorry for the mistake done in quoting. I considered your comments and changed the code but still having the same problem. I think problem is with the second while loop which writes the data to the output stream but i need some help to rectify that...
Thanks for the help,

[Ulf Dittmer]

Ulf Dittmer wrote:Make sure exactly as many bytes are streamed as there are in the image.

You can also use an HTTP monitor to look at what gets sent down the wire.

[Ranga Medagoda]

Found the error,, no problem with the reading bytes, problem was with the image inserted to the database. I used LargeObject data type instead of byteal this time, it worked.

[Niket Saini]

Hey can you please help me i have same problem you solved please give me correct code

[Bear Bibeault]

Welcome to the Ranch.

Niket Saini wrote:please give me correct code

That's not how things work around here. You write the code, and get help with it here.