Re: Loading Images into GWT via MySQL
I'd like to thank the contributors for this discussion, particularly Darren,
who provided a nice solution to a problem I had making transient images on
the server side and displaying them on the client side.
On Mon, Mar 16, 2009 at 12:40 AM, alex.d alex.dukhov...@googlemail.comwrote:
Does the img.setUrl(data:image/jpg;base64,...-trick work reliable in
all major browsers?
On 13 Mrz., 15:07, Darren siegel.dar...@gmail.com wrote:
The one case that hasn't been mentioned is when one dynamically
creates transient images on the server.
We transform various XML data sources into SVG and then transcode into
JPG (using Batik) on the fly, then base 64 encode the JPG into a
string and send it across via GWT-RPC.
Then on the client, once you have the image data from the RPC callback
(as a String):
String base64EncodedImage = ... ;
Image img = new Image();
img.setUrl(data:image/jpg;base64, + base64EncodedImage);
On Mar 13, 5:08 am, stone stones...@gmail.com wrote:
use a servlet url for downloading img.
for example: myapp/dbimage/123456
and the servlet mapping is /dbimage/*
On Mar 13, 9:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an
image of
some type, otherwise the client's browser will try to download the
picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor
greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard
HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know
that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's
response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this
buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096.
That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know
how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com
wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement
an
HttpServlet, that retrieves the data from the database and
returns it
with
the appropriate Content-Type in response to a GET http request.
Then,
you
simply place an image in your GWT code, with its source being
the path
to
the servlet (defined in your web.xml), passing along any
parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit
lost on
the
best way to do it.
I already have my image in the database. How do I retrieve
it? I read
somewhere that it can just be stored as a String. Is this
correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage
FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the
best way to
send an image over from the server to the client and how
should it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
Re: Loading Images into GWT via MySQL
Does the img.setUrl(data:image/jpg;base64,...-trick work reliable in
all major browsers?
On 13 Mrz., 15:07, Darren siegel.dar...@gmail.com wrote:
The one case that hasn't been mentioned is when one dynamically
creates transient images on the server.
We transform various XML data sources into SVG and then transcode into
JPG (using Batik) on the fly, then base 64 encode the JPG into a
string and send it across via GWT-RPC.
Then on the client, once you have the image data from the RPC callback
(as a String):
String base64EncodedImage = ... ;
Image img = new Image();
img.setUrl(data:image/jpg;base64, + base64EncodedImage);
On Mar 13, 5:08 am, stone stones...@gmail.com wrote:
use a servlet url for downloading img.
for example: myapp/dbimage/123456
and the servlet mapping is /dbimage/*
On Mar 13, 9:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image
of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor
greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns
it
with
the appropriate Content-Type in response to a GET http request.
Then,
you
simply place an image in your GWT code, with its source being the
path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I
read
somewhere that it can just be stored as a String. Is this
correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best
way to
send an image over from the server to the client and how should
it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
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Re: Loading Images into GWT via MySQL
Hi,
I will give you my honestly opinion. It seems that you are new on the
subject and I can say that I have a lot of experience on that.
First of all, don't store images on the database :)
It is true that we can do it, but depending of what you are going to
do, the site of your database will be 90% images and 10% data.
The images are always served by httpservers, even if you retrieve it
from the database. So if you store the images in the file system of
your httpserver, there is no need for network usage in case your
database is hosted in a different server.
So, use the database just to store the path of your images. Then in
GWT, retrieve the object or list of objects that contains the path for
your images. Again in GWT, Create an Image object and set the src
property.
That is all you need to do to display the image.
What do you think?
Regards,
José Vicente
On Mar 13, 2:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it
with
the appropriate Content-Type in response to a GET http request. Then,
you
simply place an image in your GWT code, with its source being the path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I read
somewhere that it can just be stored as a String. Is this correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way to
send an image over from the server to the client and how should it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Google Web Toolkit group.
To post to this group, send email to Google-Web-Toolkit@googlegroups.com
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Re: Loading Images into GWT via MySQL
use a servlet url for downloading img.
for example: myapp/dbimage/123456
and the servlet mapping is /dbimage/*
On Mar 13, 9:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it
with
the appropriate Content-Type in response to a GET http request. Then,
you
simply place an image in your GWT code, with its source being the path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I read
somewhere that it can just be stored as a String. Is this correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way to
send an image over from the server to the client and how should it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Google Web Toolkit group.
To post to this group, send email to Google-Web-Toolkit@googlegroups.com
To unsubscribe from this group, send email to
google-web-toolkit+unsubscr...@googlegroups.com
For more options, visit this group at
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Re: Loading Images into GWT via MySQL
I stored images in the filesystem.
At the client code, I use image1.setURL( /servlet/...) as 'stone'
describes above.
An HttpServlet receive it and sends the image (resized in my case).
It performs well.
On Mar 13, 10:08 am, stone stones...@gmail.com wrote:
use a servlet url for downloading img.
for example: myapp/dbimage/123456
and the servlet mapping is /dbimage/*
On Mar 13, 9:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it
with
the appropriate Content-Type in response to a GET http request. Then,
you
simply place an image in your GWT code, with its source being the path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I
read
somewhere that it can just be stored as a String. Is this correct?
So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way
to
send an image over from the server to the client and how should it
be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Google Web Toolkit group.
To post to this group, send email to Google-Web-Toolkit@googlegroups.com
To unsubscribe from this group, send email to
google-web-toolkit+unsubscr...@googlegroups.com
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-~--~~~~--~~--~--~---
Re: Loading Images into GWT via MySQL
+1 to Ze's comment
My reply assumed you had a reason why you *must* store images in DB.
If you don't Ze is right that it is a very inefficient way to store
and serve images.
On Mar 13, 9:04 am, Zé Vicente josevicentec...@gmail.com wrote:
Hi,
I will give you my honestly opinion. It seems that you are new on the
subject and I can say that I have a lot of experience on that.
First of all, don't store images on the database :)
It is true that we can do it, but depending of what you are going to
do, the site of your database will be 90% images and 10% data.
The images are always served by httpservers, even if you retrieve it
from the database. So if you store the images in the file system of
your httpserver, there is no need for network usage in case your
database is hosted in a different server.
So, use the database just to store the path of your images. Then in
GWT, retrieve the object or list of objects that contains the path for
your images. Again in GWT, Create an Image object and set the src
property.
That is all you need to do to display the image.
What do you think?
Regards,
José Vicente
On Mar 13, 2:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it
with
the appropriate Content-Type in response to a GET http request. Then,
you
simply place an image in your GWT code, with its source being the path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I
read
somewhere that it can just be stored as a String. Is this correct?
So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way
to
send an image over from the server to the client and how should it
be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Google Web Toolkit group.
To post
Re: Loading Images into GWT via MySQL
Ok, Thanks for all your replies.
So which folder should I store the images in? Here is my current
folder structure:
-bin
-src
-temp
-tomcat
-WWW
On Mar 13, 10:47 am, gregor greg.power...@googlemail.com wrote:
+1 to Ze's comment
My reply assumed you had a reason why you *must* store images in DB.
If you don't Ze is right that it is a very inefficient way to store
and serve images.
On Mar 13, 9:04 am, Zé Vicente josevicentec...@gmail.com wrote:
Hi,
I will give you my honestly opinion. It seems that you are new on the
subject and I can say that I have a lot of experience on that.
First of all, don't store images on the database :)
It is true that we can do it, but depending of what you are going to
do, the site of your database will be 90% images and 10% data.
The images are always served by httpservers, even if you retrieve it
from the database. So if you store the images in the file system of
your httpserver, there is no need for network usage in case your
database is hosted in a different server.
So, use the database just to store the path of your images. Then in
GWT, retrieve the object or list of objects that contains the path for
your images. Again in GWT, Create an Image object and set the src
property.
That is all you need to do to display the image.
What do you think?
Regards,
José Vicente
On Mar 13, 2:52 am, Itamar Ravid itamar.ira...@gmail.com wrote:
Don't forget however to set the content type on the response to an image
of
some type, otherwise the client's browser will try to download the picture
rather than display it.
On Fri, Mar 13, 2009 at 2:28 AM, gregor
greg.power...@googlemail.comwrote:
I think Itamar is right, Jack, you should use a standard HttpServlet
for this, not GWT-RPC, because this sends the image over to the
browser as byte steam, and I don't think RPC can do that.
First, I take it these are not images used in your UI (like icons
etc), 'cos those should go in an ImageBundle. I assume you know that
these images are downloaded as user selections etc.
1) Consult your MySQL docs/forum to find out how to obtain an
InputStream for the image via JDBC. You want to pass an InputStream
back to your image download HttpServlet. You don't want to read out
the image bytes yet.
2) You write the HttpServlet something like this example (there are
lots of others around):
http://snippets.dzone.com/posts/show/4629
Notice that the key is a looping read of the InputStream (which you
got from MySQL) that writes straight into the HttpServlet's response
OutputStream. Notice also it uses a buffer byte[] array. This is so
that your web server does not get it's memory clogged up with big
image byte arrays - the image bytes just get shunted from the DB
straight out to the browser via this buffer. Therefore set this buffer
small. Apache tend to use 2048 bytes. I think Oracle prefer 4096. That
sort of size for the buffer. Take care to set the response content
type so the browser knows what it's dealing with.
3) In your client you can set the Image widget's URL to your image
download HttpServlet adding a parameter for the image id.
regards
gregor
On Mar 12, 8:54 pm, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns
it
with
the appropriate Content-Type in response to a GET http request.
Then,
you
simply place an image in your GWT code, with its source being the
path
to
the servlet (defined in your web.xml), passing along any parameters
required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on
the
best way to do it.
I already have my image in the database. How do I retrieve it? I
read
somewhere that it can just be stored as a String. Is this
correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best
way to
send an
Re: Loading Images into GWT via MySQL
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it with
the appropriate Content-Type in response to a GET http request. Then, you
simply place an image in your GWT code, with its source being the path to
the servlet (defined in your web.xml), passing along any parameters required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on the
best way to do it.
I already have my image in the database. How do I retrieve it? I read
somewhere that it can just be stored as a String. Is this correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way to
send an image over from the server to the client and how should it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
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Re: Loading Images into GWT via MySQL
Hi,
I'm not too sure how to implement a HTTPServlet. Does anyone know how
to use images using RPC?
Im really stuck on this.
On Mar 12, 8:43 pm, Itamar Ravid itamar.ira...@gmail.com wrote:
The best way, IMO, is to not use GWT-RPC, but rather implement an
HttpServlet, that retrieves the data from the database and returns it with
the appropriate Content-Type in response to a GET http request. Then, you
simply place an image in your GWT code, with its source being the path to
the servlet (defined in your web.xml), passing along any parameters required
- such as the ID of the image in the database.
On Thu, Mar 12, 2009 at 12:59 PM, fatjack1...@googlemail.com
fatjack1...@googlemail.com wrote:
Hi,
I am new to loading images into GWT from MySQL and am abit lost on the
best way to do it.
I already have my image in the database. How do I retrieve it? I read
somewhere that it can just be stored as a String. Is this correct? So
my code on the server side would look like:
//Open database connection
dc.openConnection();
resultSet = dc.statement.executeQuery(SELECT CategoryImage FROM
itemcategory_table WHERE ItemType = 'Test');
while(resultSet.next()) {
String test = resultSet.getString(1);
}
dc.closeConnection();
Or have I got this completely wrong?
Next, I need to send this over to the client. What is the best way to
send an image over from the server to the client and how should it be
stored?
Any help on how to use images would be much appreciated!
Regards,
Jack
--~--~-~--~~~---~--~~
You received this message because you are subscribed to the Google Groups
Google Web Toolkit group.
To post to this group, send email to Google-Web-Toolkit@googlegroups.com
To unsubscribe from this group, send email to
google-web-toolkit+unsubscr...@googlegroups.com
For more options, visit this group at
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