Re: JDBC + PostgreSQL + LargeObjects

Paulo,

Can you provide a test case that doesn't involve jsps?  One that just
writes a file out to the filesystem and shows that the file is being
corrupted.

thanks,
--Barry


Paulo Delgado wrote:
> Oh, i don't get an error message, instead, i see on the browser, the icon for a "not an image".
> I tried to wget it, and the newly downloaded file does not match the size of the original image, and i cannot open it
withan image viewer. 
> I used the same SQL sentence using the console (the terminal), and using lo_export, and the exported image is
correctlyexported. 
>
> On Mon, 18 Feb 2002 09:44:43 -0800
> Barry Lind <barry@xythos.com> wrote:
>
>
>>Paulo,
>>
>>If you could mention what error you are getting and what version of the
>>code you are using that would be helpful.
>>
>>--Barry
>>
>>
>>Paulo Delgado wrote:
>>
>>>I'm writing a JSP which instead of generating HTML code, it sends an
>>>image to the browser. The image is retrieved from the database, where it
>>>is stored as a BLOB (an OID). I read the docs online, this is the URL:
>>>
>>>http://developer.postgresql.org/docs/postgres/jdbc-binary-data.html
>>>
>>>And this is the code (still not working)
>>>
>>>
>>>  <%@ page import="java.io.*" %>
>>>  <%@ page import="java.sql.*" %>
>>>  <%@ page import="org.postgresql.largeobject.*" %>
>>>
>>>  <%
>>>  response.setContentType("image/jpeg");
>>>  out.close();
>>>  ServletOutputStream sos = response.getOutputStream();
>>>  try
>>>  {
>>>    Class.forName("org.postgresql.Driver");
>>>  }
>>>  catch(ClassNotFoundException cnfex)
>>>  {
>>>    cnfex.printStackTrace();
>>>  }
>>>  try
>>>  {
>>>    Connection mycon;
>>>    mycon=
>>>DriverManager.getConnection("jdbc:postgresql://localhost:5432/database",
>>>"userid" , "password");
>>>    mycon.setAutoCommit(false);
>>>
>>>    // Get the Large Object Manager to perform operations with
>>>    LargeObjectManager lobj =
>>>((org.postgresql.Connection)mycon).getLargeObjectAPI();
>>>
>>>   PreparedStatement ps = mycon.prepareStatement("SELECT pic FROM
>>>mytable WHERE month='"+request.getParameter("m")+"' AND
>>>year="+request.getParameter("y"));
>>>    ResultSet rs = ps.executeQuery();
>>>    if (rs != null) {
>>>      while(rs.next()) {
>>>        //open the large object for reading
>>>        int oid = rs.getInt(1);
>>>        LargeObject obj = lobj.open(oid , LargeObjectManager.READ);
>>>
>>>        //read the data
>>>        byte buf[] = new byte[obj.size()];
>>>        obj.read(buf, 0, obj.size());
>>>
>>>        //do something with the data read here
>>>        response.setContentLength(obj.size());
>>>        int i=0;
>>>        for(i=0; i<obj.size() ; i++)
>>>        {
>>>          sos.write(buf[i]);
>>>        }
>>>        // Close the object
>>>        obj.close();
>>>      }
>>>      rs.close();
>>>    }
>>>    ps.close();
>>>    mycon.close();
>>>
>>>
>>>    }
>>>    catch(SQLException sqex)
>>>    {
>>>    out.println(sqex.toString());
>>>    }
>>>    %>
>>>
>>>
>>>the table is created like this:
>>>
>>>CREATE TABLE mytable(
>>> pic  oid,
>>> month  int2  NOT NULL,
>>> year  int2  NOT NULL,
>>> PRIMARY KEY (month, year)
>>>);
>>>
>>>I've searched all over the docs, asked all over IRC, and still does not
>>>work. any ideas?
>>>
>>>
>>>
>>>---------------------------(end of broadcast)---------------------------
>>>TIP 4: Don't 'kill -9' the postmaster
>>>
>>>
>>>
>>
>>
>
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