Retrieve Blob img from MySql and Display using servlet and jsp

[Some Aditya Mandal]

Table :-

create table imagedb (usd varchar(255) , image blob , primary key (usd), foreign key (usd) references logindb(user) on update cascade on delete cascade)

Using JSP i am able to upload the file into the blob. But icant retrieve or display;

The HTML Tag :

<table style="margin: 0px; margin-top: 15px;">
<tr>
<td id="photo">
<img src="displayimage" />
</td>

</tr>

The Servlet

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		Connection conn = null;
		 Statement stmt = null;
		 
		 try { 
         conn =   (Connection) DriverManager.getConnection(DB_URL, USER, PASS);
         stmt = (Statement) conn.createStatement();
         // constructs SQL statement
        
		Class.forName("com.mysql.jdbc.Driver");
	     Scanner s = new Scanner(System.in);

	     HttpSession session=request.getSession(false);
	     
	     String username = (String)session.getAttribute("theName");
	     
	     ResultSet rs1;
	     rs1 = stmt.executeQuery("select image from imagedb where usd='" + username + "' ;");
	     
	     if (rs1.next()) {
	      java.sql.Blob imagelink = rs1.getBlob("image");
	      String m = rs1.getString("image");
	     
	      System.out.println(imagelink.toString());
	      System.out.println(m);
	      
	      response.setHeader("expires", "0"); 
	      response.setContentType("image/jpg");
	      java.sql.Blob img = rs1.getBlob("image");
	      byte[] imgData = img.getBytes(1,(int)img.length());
	      response.setContentType("image/jpg");

          OutputStream o = response.getOutputStream();

          o.write(imgData);
          
          o.flush();
          o.close();
	    
	      System.out.println(o.toString());
	      System.out.println(imgData.toString());
	     }
	        } catch (SQLException ex) {
	            String message = "ERROR: " + ex.getMessage();
	            ex.printStackTrace();
	        } finally {
	            if (conn != null) {
	                // closes the database connection
	                try {
	                    conn.close();
	                } catch (SQLException ex) {
	                    ex.printStackTrace();
	                }
	            }
	      
	      return; 
	     }

I am not getting the image. Help.

[Ulf Dittmer]

Welcome to the Ranch.

What does "I am not getting the image" mean, exactly? What is or is not happening as you execute this code? What are the values of the involved variables? Note that using System.out.println with images, streams and arrays isn't likely to produce anything useful. Also note that ResultSet.getString doesn't work with blobs. Lastly, note that the code is wide open to SQL injection attacks; you need to use PreparedStatement.

[Dave Tolls]

And there's no point getting the blob twice:

java.sql.Blob imagelink = rs1.getBlob("image");  
...
java.sql.Blob img = rs1.getBlob("image"); 

[Bear Bibeault]

You can also enter the URL for the image servlet directly into the address bar, and if all is well, you will see the image. That diagnoses whether the problem is in the servlet, or the HTML.

Your image reference in the HTML is suspect: it should be server-relative starting with the context path. Page-relative URLs are fragile and problematic in Java web apps.