A image file will be sent to a servlet POST method.
I need to Read the request input stream and store it as image in server .
I thought of using BufferedImage and ImageIO classes .
But im Afraid of DoS attack .
Any suggestions would be helpful .
Thanks
Related
First, this is my first time building both of webservice and android client at the same time, so please kindly help me. My goal is to be able to upload a file from android apps and download it from the webservice.
This is what i did for upload (working, but im not sure this is a best way) :
Convert the image to base64 String in android apps
Send that converted string (form image) to the webservice.
Decode that string with base64_decode function in the webservice.
Save the image from the decoded string, using file_put_contents.
Input the decoded string to the BLOB field in my database.
What make me confuse is, if i already saved the image file (step 4), do i still need to save it to the BLOB column (step 5)?
Now, i got confuse with the download part. This is what im planning to do :
Get the image file from step 4 in upload using file_get_contents (return string)
Send the result (string) to my android apps
Get the string and convert it to the image (how?)
Is it all i need to download?
Do i need to use base64_decode or base64_encode in download? When do i use it?
Sorry if my question sounds silly, i still dont get the logic.
Thanks a lot for your time, all help is appreciated.
What make me confuse is, if i already saved the image file (step 4), do i still need to save it to the BLOB column (step 5)?
No you don't. You can store in DB just a reference to that file, like filename or full path.
Now, i got confuse with the download part. This is what im planning to do :
Get the image file from step 4 in upload using file_get_contents (return string)
and base64_encode it
Get the string and convert it to the image (how?)
You need to base64 decode it, because you encode it before sending it from the server. (step 1)
I would like to know if is possible get the image via POST method with a HTTP server implemented in Java (With a simple input file form). I already implemented the Java server but I can only get text files via POST method it's because that the my application only copies the file content to another empty file creating the same file with the same characteristics. This does not work with image file or other files, this can only work with text file.
Anyone know how to implement it with images?
Some coordinates would be of great help!
Thanks in advance!
As far as i know you should create something like it:
Server-side: If you use a servlet that receive data in post you have to get the outputStream from the response. Once you have it it is done because you write the data image on the stream.
For example let's suppose your image is a file stored in the server you could do:
response.setContentLength((int) fileSize);
byte b[] = new byte[1024];
while ( fOutStream.read(b) != -1)
response.getOutputStream().write(b);
fOutStream.close() ;
Where the fOutStream is the source stream (your image).
I have a simple TCP serversocket that will GET a byte array. This GET comes from when entering a website on this server that contains an img src link to a gif image, the requests looks like this:
GET /myHome.htm HTTP/1.1
GET /house.gif HTTP/1.1
Now the byte array is done like this:
byte[] fileByte = Files.readAllBytes(filePath);
To print the website which contains this image I do this:
out.writeBytes(new String(fileByte));
out:
DataOutputStream out= new DataOutputStream(socketClient.getOutputStream());
Now to make the image display I think I have to use something else then
out.writeBytes()
but I do not know for sure. Anybody knows how to make the image display? Right now the image just dont show at all.
First, make sure your GIF file is not corrupted. (Happened to me before, too).
If that is the case, try this code for sending the GIF file:
byte[] fileByte = Files.readAllBytes(filePath);
writer.writeBytes("HTTP/1.1 200 OK\r\n");
writer.writeBytes("Content-Type: image/gif\r\n");
writer.writeBytes("Content-Length: "+fileByte.length+"\r\n");
writer.writeBytes("\r\n");
writer.write(fileByte, 0, fileByte.length);
And then try to navigate to "house.gif" directly instead of "myHome.htm". Let me know in the comments what this does.
Previous answer attempts:
I think I may have misunderstood your question. Let me try with a different answer:
You are not sure how to figure out on the server when to return the HTML file myHome.htm and when to return house.gif?
I think for this you need to simply parse out the requested URL. Just check whether it contains "house.gif" or not. Then, depending on this, you either return the HTML file as you described above, or you send the .gif file, making sure that you use
writer.write(fileByte, 0, fileByte.length);
to send the binary data and that you set a reply header of
Content-Type: image/gif
In both cases (for the HTML file and the GIF file), though, you should prepend the data you are sending with correct HTTP response headers. Don't take the page-title the wrong way, but this site might help: http://net.tutsplus.com/tutorials/other/http-headers-for-dummies/
And just to make sure: Your server will be receiving TWO independent requests. The first one will ask for the HTML file, the second one will ask for the GIF file. So you send either one or the other. So, there's no "special way" to send the GIF instead of the HTML file. You use the same clientSocket. But it's a different connection.
Previous answer(s):
I think you might be missing the mime-type of your returned data. Try adding the following HTTP header to your reply:
Content-Type: image/gif
Actually... Are you sending a correct HTTP reply at all (including headers, specifically Content-Length)? If not, shoot me a comment and I'll post the code that you need for this.
If, for some reason, you cannot set the content-type header to let the browser know that you are sending it an image, you might be able to load the binary data on the client with an XMLHttpRequest into a JavaScript function rather than specifying it as the source Url of an img tag. Then you can use JavaScript to encode the binary data into a dataURI (http://en.wikipedia.org/wiki/Data_URI_scheme) with the correct mime type and set that as the source of the image.
Actually, I just noticed something in your code:
new String(fileByte)
might interpret the fileBytes as unicode characters rather than binary. Then, when you write this to the writer, it might screw it up as probably not all data in the image are valid unicode. Try replacing the line with this:
writer.write(fileByte, 0, fileByte.length);
Maybe this is all you need to do to fix it???
I am working with Dropbox API using JAVA SDK. I try to get the thumbnail for each image in my dropbox account via API. Honestly, after I read the class and they just provided the description which is not useful enough for the beginner. I begin my code like this
public void getThumbnails() throws DropboxException{
DropboxInputStream dis = api.getThumbnailStream("/Koala.jpg", ThumbSize.ICON_256x256, ThumbFormat.JPEG);
}
What I don't understand is:
I should return something to client side in order to show the thumbnail I got from DropboxAPI but I don't know what I should return. Maybe DropboxInputStream?
How do I get the thumbnail from API? I try to find the example or guide for a day but I can't find any guide...
please someone guide me how to get the thumbnail via dropbox API
DropboxInputStream is just a FilterInputStream so after you get the input stream like you wrote you can just iterate the input stream and read it.
Then it's only a question of the way you need to present it.
Is it a Swing application you are writing? how do you need to show that image?
You should be able to read the Image with ImageIO.read
Image image = ImageIO.read(dis);
http://docs.oracle.com/javase/6/docs/api/javax/imageio/ImageIO.html
I'm currently writing some MATLAB code to interact with my company's internal reports database. So far I can access the HTML abstract page using code which looks like this:
import com.mathworks.mde.desk.*;
wb=com.mathworks.mde.webbrowser.WebBrowser.createBrowser;
wb.setCurrentLocation(ReportURL(8:end));
pause(1);
s={};
while isempty(s)
s=char(wb.getHtmlText);
pause(.1);
end
desk=MLDesktop.getInstance;
desk.removeClient(wb);
I can extract out various bits of information from the HTML text which ends up in the variable s, however the PDF of the report is accessed via what I believe is a JavaScript command (onClick="gotoFulltext('','[Report Number]')").
Any ideas as to how I execute this JavaScript command and get the contents of the PDF file into a MATLAB variable?
(MATLAB sits on top of Java, so I believe a Java solution would work...)
I think you should take a look at the JavaScript that is being called and see what the final request to the webserver looks like.
You can do this quite easily in Firefox using the FireBug plugin.
https://addons.mozilla.org/en-US/firefox/addon/1843
Once you have found the real server request then you can just request this URL or post to this URL instead of trying to run the JavaScript.
Once you have gotten the correct URL (a la the answer from pjp), your next problem is to "get the contents of the PDF file into a MATLAB variable". Whether or not this is possible may depend on what you mean by "contents"...
If you want to get the raw data in the PDF file, I don't think there is a way currently to do this in MATLAB. The URLREAD function was the first thing I thought of to read content from a URL into a string, but it has this note in the documentation:
s = urlread('url') reads the content
at a URL into the string s. If the
server returns binary data, s will
be unreadable.
Indeed, if you try to read a PDF as in the following example, s contains some text intermingled with mostly garbage:
s = urlread('http://samplepdf.com/sample.pdf');
If you want to get the text from the PDF file, you have some options. First, you can use URLWRITE to save the contents of the URL to a file:
urlwrite('http://samplepdf.com/sample.pdf','temp.pdf');
Then you should be able to use one of two submissions on The MathWorks File Exchange to extract the text from the PDF:
Extract text from a PDF document by Dimitri Shvorob
PDF Reader by Tom Gaudette
If you simply want to view the PDF, you can just open it in Adobe Acrobat with the OPEN function:
open('temp.pdf');
wb=com.mathworks.mde.webbrowser.WebBrowser.createBrowser;
wb.executeScript('javascript:alert(''Some code from a link'')');
desk=com.mathworks.mde.desk.MLDesktop.getInstance;
desk.removeClient(wb);