Java and xhtml

Hello, How can I get in java the value of an input build with apache.ecs.xhtml? I searched an hour or so on google and haven't found anything related to that. E.g: input hidden_input = new input(); input.setID(prefix + name); ... and at a certain moment its value changes (with javascript). Then I need its value in java. Maybe there is a way to get it using xwiki api somehow... I would be very thankful for an answer. Thank you very much. Evelina