HtmlUnit 的使用

HtmlUnit是Java一个开发工具包，利用它写的Java代码可以模仿人点击link，提交表单的功能.主要是用来测试. 
    可以到这里http://htmlunit.sourceforge.net/了解详细信息. 
    模仿一个特定的浏览器 

    通常您会希望将模拟特定浏览器.这样做是通过传递  com.gargoylesoftware.htmlunit.BrowserVersion到的WebClient构造。常数提供了一些常见的浏览器，但您可以创建自己的特定版本的执行一个BrowserVersion 。 
   

public void homePage_Firefox() throws Exception {
    final WebClient webClient = new WebClient(BrowserVersion.FIREFOX_2);
    final HtmlPage page = webClient.getPage("http://htmlunit.sourceforge.net");
    assertEquals("HtmlUnit - Welcome to HtmlUnit", page.getTitleText());
}

找到特定元素 
    一旦你得到了一个参考的HtmlPage ，您可以搜索特定HtmlElement之一的'get'方法，或使用的XPath 。下面是一个例子，找到一个'线'的ID ，搜到了锚的名字： 
get 方法 
  

public void getElements() throws Exception {
final WebClient webClient = new WebClient();
final HtmlPage page = webClient.getPage("http://htmlunit.sourceforge.net");
final HtmlDivision div = page.getHtmlElementById("some_div_id");
final HtmlAnchor anchor = page.getAnchorByName("anchor_name");

Xpath 

public void xpath() throws Exception {
    final WebClient webClient = new WebClient();
    final HtmlPage page = webClient.getPage("http://htmlunit.sourceforge.net");

    //get list of all divs
    final List<?> divs = page.getByXPath("//div");

    //get div which has a 'name' attribute of 'John'
    final HtmlDivision div = (HtmlDivision) page.getByXPath("//div[@name='John']").get(0);
}

使用代理服务器 
最后WebClient构造让您可以指定代理服务器信息，在这些情况下，你需要通过一个连接。 

public void homePage_proxy() throws Exception {
    final WebClient webClient = new WebClient(BrowserVersion.FIREFOX_2, "http://myproxyserver", myProxyPort);

    //set proxy username and password
    final DefaultCredentialsProvider credentialsProvider = (DefaultCredentialsProvider) webClient.getCredentialsProvider();
    credentialsProvider.addProxyCredentials("username", "password");

    final HtmlPage page = webClient.getPage("http://htmlunit.sourceforge.net");
    assertEquals("HtmlUnit - Welcome to HtmlUnit", page.getTitleText());
}

指定此BrowserVersion将改变发送到服务器的用户代理header，这行影响一Javascript的一些行为 。 
提交表单 
我们经常需要改变表单元素的值，并且提交到服务器： 

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();
}