Is your goal to show the image in an img tag in the web browser? I have user uploadable images on my gwt website and to present the images to users i use an http servlet. I have an img tag rendered in the client that references the image from the servlet. Since my images are saved in the DB, the image servlet processes the users request, finds the image that they are requesting and renders the file to the output stream. Pretty much all you need to do is configure the content type on the response.
On Apr 15, 9:48 am, Ahmet <[email protected]> wrote: > Hi everyone, > > My application has an upload file feature and allow users to upload > image files to the server using an httpServlet. That part works fine, > the file gets uploaded and placed in the WEB-INF folder (I don't want > public access), required url and other info is filled into the > database using Hibernate. > > The problem is when I want to retrieve the image on the client side. > My user pojo knows the url of its image, but I can't instantiate an > Image object and send it over an RPC call since it is not > serializable. I decided to transform the image file, a jpg, into a > byte[] on the server side and then transfer the byte[] over the RPC > call, however, I it doesn't work. > > I get no errors on the server side, the RPC call returns, but my > client reports a failure: > > SEVERE: Exception while dispatching incoming RPC call > java.lang.RuntimeException: java.lang.ClassCastException: [B cannot be > cast to [Ljava.lang.Object; > > My service code: > public byte[] getImageByUrl(String url) { > > ByteArrayOutputStream baos = new ByteArrayOutputStream(); > try{ > File file = new File(url); > ObjectOutputStream oos = new ObjectOutputStream(baos); > oos.writeObject(file); > }catch(Exception ioe){ > ioe.getMessage(); > } > return baos.toByteArray(); > > } > > My client code: > service.getImageByUrl(url, new AsyncCallback<byte[]>() { > @Override > public void onFailure(Throwable arg0) > { > log("getImageByUrl failed"); > log(arg0.getMessage()); > } > @Override > public void onSuccess(byte[] arg0) { > //reconstruct file > } > > } > > I send a byte[] and recieve a byte[], I checked the contents of the > array from the server side, it is not null and gets returned, however > the client side can not accept it... Why can this be ? > > I have done some research and it seems like using an httpServlet is > better than using an RPC call when making a binary data transfer, > therefore I am inclined to using the httpServlet for downloading the > image, however what I ultimately achive is not having to save the file > on my client side to access its content. Is it possible to transfer > the Image object over the httpServlet to dynamically use it as it is > recieved on the client side ? > > I am not sure about using data://url s as they are not supported by > all browsers, but seems as the simplest solution. > > Thank you for your opinions.. > > Regards, > Ahmet > > -- > You received this message because you are subscribed to the Google Groups > "Google Web Toolkit" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group > athttp://groups.google.com/group/google-web-toolkit?hl=en. -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
