How to retrieve blob image from mysql database in jsp - mysql

Question

while (rsimg.next())
{
Blob photo = rsimg.getBlob("thumbnails");
}
after that what I have to do to show the image in browser.

Answer 1

Try this code in your servlet file , because it will easier to use and identify errors rather than jsp
import java.sql.*;
import java.io.*;
public class RetrieveImage {
public static void main(String[] args) {
try{
Class.forName("YOUR DRIVER NAME");
Connection con=DriverManager.getConnection(
"URL","USERNAME","PASSWORD");
PreparedStatement ps=con.prepareStatement("select * from TBL_NAME");
ResultSet rs=ps.executeQuery();
if(rs.next()){//now on 1st row
Blob b=rs.getBlob(2); //2 means 2nd column data
byte barr[]=b.getBytes(1,(int)b.length()); //1 means first image
FileOutputStream fout=new FileOutputStream("d:\\IMG_NAME.jpg");
fout.write(barr);
fout.close();
}//end of if
System.out.println("ok");
con.close();
}catch (Exception e) {e.printStackTrace(); }
}
}
Now you can load the image from path given in the above .
Hope this helps !!

Answer 2

In order to show image on web, you will have to use 'img' tag and populate it's 'src' attribute with relative path of your image.
Now the problem is, 'img' tag cannot take binary data as 'src' i.e your client cannot access files from database directly. So what you can do is, create a Servlet that loads the file from database and then streams the file via HttpServletResponse.
Your Servlet will looks something like this:
public class DispalyImage extends HttpServlet {
private static final int DEFAULT_BUFFER_SIZE = 10240; // 10KB.
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
// Code to access database and get blob image.
// String id = HttpServletRequest.getParameter("id");
// select from table where id='id'
Blob photo = rsimg.getBlob("thumbnails");
response.reset();
response.setBufferSize(DEFAULT_BUFFER_SIZE);
response.setContentType("image/jpeg");
response.setHeader("Content-Length", String.valueOf(photo.length()));
// Prepare streams.
BufferedInputStream input = null;
BufferedOutputStream output = null;
try {
// Open streams.
input = new BufferedInputStream(new FileInputStream(file), DEFAULT_BUFFER_SIZE);
output = new BufferedOutputStream(response.getOutputStream(), DEFAULT_BUFFER_SIZE);
// Write file contents to response.
byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
int length;
while ((length = input.read(buffer)) > 0) {
output.write(buffer, 0, length);
}
} finally {
output.close();
input.close();
}
}
}
Now the problem is, how would your Servlet know which image to stream? Just provide your key as parameter to Servlet. The key would be used to load your image
Assuming you will provide key as 'id', you will display image as
<img src="DisplayImage?id=imageId"></img>
You can retrieve id using HttpServletRequest.getParameter("id") method in your DisplayImage Servlet and load image from database using the id.
Refer FileServlet by BalusC, which has nice example and explanation on how files can ve served from database.