Image is not displayed from Oracle table using servlet

[subir adhikari]

After a long trial ,I finally successfully able to upload an image to an oracle database. At least my code says so. However to check whether the image has been successfully I wrote a servlet. After running the servlet I get a black screen in my browser and nothing else. The servlet code is:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class DisplayImage extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException  {
    // TODO Auto-generated method stub
     try {
         Class.forName("oracle.jdbc.driver.OracleDriver");  
         String url = "jdbc:oracle:thin:@localhost:1521:XE";
         Connection con = DriverManager.getConnection(url,"system","root");
            PreparedStatement ps = con.prepareStatement("select image from insertimage");
            ResultSet rs = ps.executeQuery();
            rs.next();
            Blob  b = rs.getBlob("image");
            response.setContentType("image/jpeg");
            response.setContentLength( (int) b.length());
            InputStream is = b.getBinaryStream();
            OutputStream os = response.getOutputStream();
            byte buf[] = new byte[(int) b.length()];
            is.read(buf);
            os.write(buf);
            os.close();
        }
        catch(Exception ex) {
             System.out.println(ex.getMessage());
        }
    } 

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
    } 
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        processRequest(request, response);
}

  }

By the way, as I am totally new to this, I took extensive help from this link.http://www.srikanthtechnologies.com/blog/java/fileupload.aspx.
EDIT : I get the black screen if only viewed from FF , but if viewed from internal web browser of Eclipse it shows me a single word upload . Very strange behavior!! Please help!!

[Rob Spoor]

InputStream.read(byte[]) is not guaranteed to read everything in one call. No matter what InputStream you use, you should always use a loop until you're actually done. You can find an example in https://www.coderanch.com/how-to/java/AvailableDoesntDoWhatYouThinkItDoes.

[subir adhikari]

So I changed the code a little bit and wrote:

byte[] buffer = new byte[(int) b.length()];
	            while(is.read(buffer)!=-1)
	            {
	            is.read(buffer);
	            os.write(buffer);
	            }
	            
	            os.close();

But it did not change the result.

[Rob Spoor]

You're still not doing it right. You are now reading data twice in each loop iteration. The data read by the first one will be discarded and overwritten by the data read by the second one. Also, you write all contents of the byte[], even if less was read. Didn't you check the link I posted? It shows you exactly how you can do this.