How to programmatically access web page in java

The super simple way to do this is using HtmlUnit here:

http://htmlunit.sourceforge.net/

and what you want to do can be as simple as:

@Test
public void homePage() throws Exception {
    final WebClient webClient = new WebClient();
    final HtmlPage page = webClient.getPage("http://htmlunit.sourceforge.net");
    assertEquals("HtmlUnit - Welcome to HtmlUnit", page.getTitleText());
}

Try HtmlUnit

HtmlUnit is a "GUI-Less browser for Java programs". It models HTML documents and provides an API that allows you to invoke pages, fill out forms, click links, etc... just like you do in your "normal" browser.

Example code for submiting form:

@Test
public void submittingForm() throws Exception {
    final WebClient webClient = new WebClient();

    // Get the first page
    final HtmlPage page1 = webClient.getPage("http://some_url");

    // Get the form that we are dealing with and within that form, 
    // find the submit button and the field that we want to change.
    final HtmlForm form = page1.getFormByName("myform");

    final HtmlSubmitInput button = form.getInputByName("submitbutton");
    final HtmlTextInput textField = form.getInputByName("userid");

    // Change the value of the text field
    textField.setValueAttribute("root");

    // Now submit the form by clicking the button and get back the second page.
    final HtmlPage page2 = button.click();

    webClient.closeAllWindows();
}

For more details check: http://htmlunit.sourceforge.net/gettingStarted.html

Take a look at the apache HttpClient project, or if you need to run Javascript on the page, try HttpUnit.