BLOB(image) -> ByteArrayOutputStream -> display on screen

[Stefan Renemeister]

Hi all,

I'm fairly new to java, and as an exercise created a database (mysql), containing a table "photo_tbl" in which resides a couple pictures as BLOBs.
I created a java class, shown below that manages to read these images out of my database into a ByteArrayOutputStream.

My big question to u: How can I get the ByteArrayOutputStream to display as the original photo? (and not some freaky binary output )

public class databaseConnection {
    private int photo;

    public void loadDriver() {
            try {
            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("Driver loaded");
            }
            catch (Exception ex) {
           System.out.println("not Connected, com.mysql.jdbc.Driver class not found");
            }
    }

    public void connect() throws IOException {
        Connection conn = null;

    try {
        conn = DriverManager.getConnection("jdbc:mysql://www.cre8-iv.nl:1025/photo_dbs","scoobie","doobiedoo");
        System.out.println("Connected");

        Statement stmt = null;
        ResultSet rs = null;
        stmt =  (Statement) conn.createStatement();
        rs =    (ResultSet) stmt.executeQuery("SELECT id, photo FROM photo_tbl");

        while (rs.next()) {
            int i = rs.getInt("id");
            Blob ph = rs.getBlob("photo");

        System.out.println(i);
        System.out.println(ph);

        InputStream in = ph.getBinaryStream();
        ByteArrayOutputStream out = new ByteArrayOutputStream();

        int length = (int) ph.length();
        int bufferSize = 1024;
        
        byte[] buffer = new byte[bufferSize];

        while ((length = in.read(buffer)) != -1) {
            System.out.println("writing " + length + " bytes");
            out.write(buffer, 0, length);
        }

        in.close();
        }
                }

    catch (SQLException ex) {
    // handle any errors
    System.out.println("SQLException: " + ex.getMessage());
    System.out.println("SQLState: " + ex.getSQLState());
    System.out.println("VendorError: " + ex.getErrorCode());
    }
}
}    

[ujjwal soni]

Hi,

You can do something like this ::

<%@ page import="java.io.*"%>
<%
       // Place a gif file in your web app's root folder for test.
       File f = new File(application.getRealPath("/temp.gif"));
       FileInputStream fis = new FileInputStream(f);
       byte[] imgData = new byte [(int)f.length()];
       fis.read(imgData);
       //response.reset();
       response.setContentType("image/gif");
       //out.clear();
       OutputStream o = response.getOutputStream();
       o.write(imgData);
       o.flush(); 
       o.close();
%>

[Stefan Renemeister]

ujjwal soni wrote:Hi,

You can do something like this ::

<%@ page import="java.io.*"%>
<%
       // Place a gif file in your web app's root folder for test.
       File f = new File(application.getRealPath("/temp.gif"));
       FileInputStream fis = new FileInputStream(f);
       byte[] imgData = new byte [(int)f.length()];
       fis.read(imgData);
       //response.reset();
       response.setContentType("image/gif");
       //out.clear();
       OutputStream o = response.getOutputStream();
       o.write(imgData);
       o.flush(); 
       o.close();
%>

Hi ujjwal soni,
thank you for your reply. Perhaps I don't understand you properly, or I am lacking knowledge here, but it seems that you want me to put a file on disk first?
In my current situation I have an application that delivers an ByteArrayOutputStream, containing the bytes of an image. How can I show that on a web page?
If I need to transform that to a file on disk, that's ok with me, but how?

Once again, thank you for your help.

[ujjwal soni]

Hi Stefan

Try below code

OutputStream outputStream = new FileOutputStream ("c:/ujjwal/a.jpg");  // path where you want to save the file
byteArrayOutputStream.writeTo(outputStream); //this byteArrayOutputStream is an original object which has image contents

Then, you can refer that image on jsp or html page like :

<img />

[Stefan Renemeister]

ujjwal soni wrote:Hi Stefan

Try below code

OutputStream outputStream = new FileOutputStream ("c:/ujjwal/a.jpg");  // path where you want to save the file
byteArrayOutputStream.writeTo(outputStream); //this byteArrayOutputStream is an original object which has image contents

Then, you can refer that image on jsp or html page like :

<img />

Hi ujjwal,

allright, but where in my code do I need to add this? in the while I guess? If I do so, netbeans throws me a:
"Error non-static method writeTo(java.io.OutputStream) cannot be referenced from a static context"
What is this about?

And my second question would be: am I doing this in the proper way now? It seems like an awful long way just to show a picture from a database.

[Stefan Renemeister]

Hi Ujjwal,

I think I get it now, it works now, this is what it finally is:

  public class databaseConnection {
    private int photo;

    public void loadDriver() {
            try {
            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("Driver loaded");
            }
            catch (Exception ex) {
           System.out.println("not Connected, com.mysql.jdbc.Driver class not found");
            }
    }

    public void connect() throws IOException {
        Connection conn = null;

    try {
        conn = DriverManager.getConnection("jdbc:mysql://www.cre8-iv.nl:1025/photo_dbs","scooby","doobiedoo");
        System.out.println("Connected");

        Statement stmt = null;
        ResultSet rs = null;
        stmt =  (Statement) conn.createStatement();
        rs =    (ResultSet) stmt.executeQuery("SELECT id, photo FROM photo_tbl where id = 1");

        while (rs.next()) {
            int i = rs.getInt("id");
            Blob ph = rs.getBlob("photo");

        System.out.println(i);
        System.out.println(ph);

        InputStream in = ph.getBinaryStream();
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        OutputStream outputStream = new FileOutputStream ("/Desktop/a.jpg");

        int length = (int) ph.length();
        int bufferSize = 1024;

        byte[] buffer = new byte[bufferSize];

        while ((length = in.read(buffer)) != -1) {
            System.out.println("writing " + length + " bytes");
            out.write(buffer, 0, length);   
        }
        out.writeTo(outputStream); 
        in.close();
        }
                }

    catch (SQLException ex) {
    // handle any errors
    System.out.println("SQLException: " + ex.getMessage());
    System.out.println("SQLState: " + ex.getSQLState());
    System.out.println("VendorError: " + ex.getErrorCode());
    }
}
}  

Thanks a lot, you were of great help!
Only question that remains is: am I doing this proper? It seems so inefficient, having one output stream filling the other?

[Jeanne Boyarsky]

Stefan Renemeister wrote: It seems so inefficient, having one output stream filling the other?

Your code looks fine. The having one stream fill another is necessary. It disconnects the image from the database's blob/output stream and puts it in one that is more usable - the file.