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 with an image viewer.
> I used the same SQL sentence using the console (the terminal), and using lo_export, and the exported image is correctly exported.
>
> On Mon, 18 Feb 2002 09:44:43 -0800
> Barry Lind <barry(at)xythos(dot)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
>>>
>>>
>>>
>>
>>
>
> ---------------------------(end of broadcast)---------------------------
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>
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