You have to be more specific about it...

i need to make an image smaller and return it to the httpresponse, i want the image to be small so that it would fit a mobile phone so the image will come from the internet and minimize it to send to the fone

There is javax.imageio as part of Java that you can use. However not always suficient for the task. You may want to consider Java Advance Imaging or even better Java Advanced Imaging Image I/O. Please take the note that this sugestions are good as far image resizing is done on the server. You would not be able to implement it on mobile device derictly!
There could be solution if you use Advanced Graphics and User Interface (AGUI) Optional Package for Java Platform, Micro Edition (JSR-209) or one of the custom libraries for 2D & 3D from companies like Nokia or Sony Ericsson but I did not try them yet.