Обсуждение: JDBC + PostgreSQL + LargeObjects
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?
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 > >
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 correctly exported. 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 > > > > > > >
oh, i did "View source" and netscape crashed =) (don't have IEplore, linux box only) On Tue, 19 Feb 2002 06:49:06 +1100 Justin Clift <justin@postgresql.org> wrote: > Hi Paulo, > > From the browser window where you're getting the icon for "not an > image", do a "View Source" of the .html page. > > The way in which web pages work, there's probably an error buried in the > source code, and the browser isn't showing it to you. > > Doesn't always work, but commonly this is the case. > > Hope that's helpful. > > :-) > > Regards and best wishes, > > Justin Clift > > > 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 itwith an 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 > > > > > > > > > > > > > > > > > > > > > ---------------------------(end of broadcast)--------------------------- > > TIP 6: Have you searched our list archives? > > > > http://archives.postgresql.org > > -- > "My grandfather once told me that there are two kinds of people: those > who work and those who take the credit. He told me to try to be in the > first group; there was less competition there." > - Indira Gandhi >
Hi Paulo, From the browser window where you're getting the icon for "not an image", do a "View Source" of the .html page. The way in which web pages work, there's probably an error buried in the source code, and the browser isn't showing it to you. Doesn't always work, but commonly this is the case. Hope that's helpful. :-) Regards and best wishes, Justin Clift 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 > > > > > > > > > > > > > > ---------------------------(end of broadcast)--------------------------- > TIP 6: Have you searched our list archives? > > http://archives.postgresql.org -- "My grandfather once told me that there are two kinds of people: those who work and those who take the credit. He told me to try to be in the first group; there was less competition there." - Indira Gandhi
Ok folks, now it works! thank you all! (i'm using a servlet to avoid the white spaces)
Now i have another problem, when the servlet is writing the bytes to the outputstream, the cpu load increases to 100%,
iguess the problem is in the for() block, should i look for another way of doing this? or use perl? or what?
check it out:
import javax.servlet.*;
import java.io.*;
import javax.servlet.http.*;
import java.sql.*;
import org.postgresql.largeobject.*;
public class show_coctel extends HttpServlet
{
public void doGet(HttpServletRequest request , HttpServletResponse response) throws ServletException, IOException
{
ServletOutputStream out = response.getOutputStream();
response.setContentType("image/jpeg");
try
{
Class.forName("org.postgresql.Driver");
}
catch(ClassNotFoundException cnfex)
{
cnfex.printStackTrace();
}
try
{
Connection mycon;
mycon= DriverManager.getConnection("jdbc:postgresql://localhost:5432/database", "username" , "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 cocteles 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++)
{
out.write(buf[i]);
}
// Close the object
obj.close();
}
rs.close();
}
ps.close();
mycon.close();
}
catch(SQLException sqex)
{
out.println(sqex.toString());
}
}
}
I would just change this:
...
int i=0;
for(i=0; i<obj.size() ; i++)
{
out.write(buf[i]);
}
...
to this:
...
out.write(buf);
out.flush();
out.close();
...
Writing it out 1 byte at a time would be way too inefficient and is
probably why your CPU pegs.
Cheers,
Marc
Paulo Delgado wrote:
> Ok folks, now it works! thank you all! (i'm using a servlet to avoid the white spaces)
> Now i have another problem, when the servlet is writing the bytes to the outputstream, the cpu load increases to
100%,i guess the problem is in the for() block, should i look for another way of doing this? or use perl? or what?
>
> check it out:
>
> import javax.servlet.*;
> import java.io.*;
> import javax.servlet.http.*;
> import java.sql.*;
> import org.postgresql.largeobject.*;
>
> public class show_coctel extends HttpServlet
> {
> public void doGet(HttpServletRequest request , HttpServletResponse response) throws ServletException, IOException
> {
> ServletOutputStream out = response.getOutputStream();
> response.setContentType("image/jpeg");
> try
> {
> Class.forName("org.postgresql.Driver");
> }
> catch(ClassNotFoundException cnfex)
> {
> cnfex.printStackTrace();
> }
> try
> {
> Connection mycon;
> mycon= DriverManager.getConnection("jdbc:postgresql://localhost:5432/database", "username" , "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 cocteles 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++)
> {
> out.write(buf[i]);
> }
> // Close the object
> obj.close();
> }
> rs.close();
> }
> ps.close();
> mycon.close();
> }
> catch(SQLException sqex)
> {
> out.println(sqex.toString());
> }
> }
> }
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
> (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
>
>
--
01010101010101010101010101010101010101010101010101
Marc P. Lavergne [wk:650-576-7978 hm:407-648-6996]
Senior Software Developer
Global Knowledge Management
Worldwide Support Technologies
Openwave Systems Inc.
--
"Anyone who slaps a 'this page is best viewed with
Browser X' label on a Web page appears to be
yearning for the bad old days, before the Web,
when you had very little chance of reading a
document written on another computer, another word
processor, or another network."
-Tim Berners-Lee (Technology Review, July 1996)
01010101010101010101010101010101010101010101010101
Thank you very much! now it works perfectly! w00t!
On Mon, 18 Feb 2002 15:37:59 -0500
Marc Lavergne <mlavergne-pub@richlava.com> wrote:
> I would just change this:
>
> ...
> int i=0;
> for(i=0; i<obj.size() ; i++)
> {
> out.write(buf[i]);
> }
> ...
>
> to this:
>
> ...
> out.write(buf);
> out.flush();
> out.close();
> ...
>
> Writing it out 1 byte at a time would be way too inefficient and is
> probably why your CPU pegs.
>
> Cheers,
>
> Marc
>
>
> Paulo Delgado wrote:
>
> > Ok folks, now it works! thank you all! (i'm using a servlet to avoid the white spaces)
> > Now i have another problem, when the servlet is writing the bytes to the outputstream, the cpu load increases to
100%,i guess the problem is in the for() block, should i look for another way of doing this? or use perl? or what?
> >
> > check it out:
> >
> > import javax.servlet.*;
> > import java.io.*;
> > import javax.servlet.http.*;
> > import java.sql.*;
> > import org.postgresql.largeobject.*;
> >
> > public class show_coctel extends HttpServlet
> > {
> > public void doGet(HttpServletRequest request , HttpServletResponse response) throws ServletException,
IOException
> > {
> > ServletOutputStream out = response.getOutputStream();
> > response.setContentType("image/jpeg");
> > try
> > {
> > Class.forName("org.postgresql.Driver");
> > }
> > catch(ClassNotFoundException cnfex)
> > {
> > cnfex.printStackTrace();
> > }
> > try
> > {
> > Connection mycon;
> > mycon= DriverManager.getConnection("jdbc:postgresql://localhost:5432/database", "username" , "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 cocteles 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++)
> > {
> > out.write(buf[i]);
> > }
> > // Close the object
> > obj.close();
> > }
> > rs.close();
> > }
> > ps.close();
> > mycon.close();
> > }
> > catch(SQLException sqex)
> > {
> > out.println(sqex.toString());
> > }
> > }
> > }
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 2: you can get off all lists at once with the unregister command
> > (send "unregister YourEmailAddressHere" to majordomo@postgresql.org)
> >
> >
>
>
> --
> 01010101010101010101010101010101010101010101010101
>
> Marc P. Lavergne [wk:650-576-7978 hm:407-648-6996]
> Senior Software Developer
> Global Knowledge Management
> Worldwide Support Technologies
> Openwave Systems Inc.
>
> --
>
> "Anyone who slaps a 'this page is best viewed with
> Browser X' label on a Web page appears to be
> yearning for the bad old days, before the Web,
> when you had very little chance of reading a
> document written on another computer, another word
> processor, or another network."
> -Tim Berners-Lee (Technology Review, July 1996)
>
> 01010101010101010101010101010101010101010101010101
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 2: you can get off all lists at once with the unregister command
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>
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 >>> >>> >>> >> >> > > ---------------------------(end of broadcast)--------------------------- > TIP 6: Have you searched our list archives? > > http://archives.postgresql.org > >
Your problem is very simple. You cannot allow ANYTHING other than the image to go out via the JSP. In your example given, You have a whole lot of whitespace going out. I suggest you put, guarding each newline, <%-- at the end of the line and --%> at the beginning of the next - or just merge the tags, e.g.: <%@ page import="java.io.*" %><%@ page import="java.sql.*" %><%@ page import="org.postgresql.largeobject.*" %><% // rest of code... %><%-- DO NOT END WITH A NEWLINE!!! --%> Note that you can also combine multiple import statements into one with code such as: import="java.io.*,java.sql.*,org.postgresql.largeobject.*". Cheers, Doug At 01:27 PM 2/18/2002, you 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@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 > > > > > > > > > > > > > >---------------------------(end of broadcast)--------------------------- >TIP 6: Have you searched our list archives? > >http://archives.postgresql.org