问题
I'm having this weird problem with HtmlUnit in Java. I am using it to download some data from a website, the process is something like this:
1 - Login
2 - For each element (cars)
----- 3 Search for car
----- 4 Download zip file from a link
The code:
Creation of the webclient:
webClient = new WebClient(BrowserVersion.FIREFOX_3_6);
webClient.setJavaScriptEnabled(true);
webClient.setThrowExceptionOnScriptError(false);
DefaultCredentialsProvider provider = new DefaultCredentialsProvider();
provider.addCredentials(USERNAME, PASSWORD);
webClient.setCredentialsProvider(provider);
webClient.setRefreshHandler(new ImmediateRefreshHandler());
Login:
public void login() throws IOException
{
page = (HtmlPage) webClient.getPage(URL);
HtmlForm form = page.getFormByName("formLogin");
String user = USERNAME;
String password = PASSWORD;
// Enter login and password
form.getInputByName("LoginSteps$UserName").setValueAttribute(user);
form.getInputByName("LoginSteps$Password").setValueAttribute(password);
// Click Login Button
page = (HtmlPage) form.getInputByName("LoginSteps$LoginButton").click();
webClient.waitForBackgroundJavaScript(3000);
// Click on Campa area
HtmlAnchor link = (HtmlAnchor) page.getElementById("ctl00_linkCampaNoiH");
page = (HtmlPage) link.click();
webClient.waitForBackgroundJavaScript(3000);
System.out.println(page.asText());
}
Search for car in website:
private void searchCar(String _regNumber) throws IOException
{
// Open search window
page = page.getElementById("search_gridCampaNoi").click();
webClient.waitForBackgroundJavaScript(3000);
// Write plate number
HtmlInput element = (HtmlInput) page.getElementById("jqg1");
element.setValueAttribute(_regNumber);
webClient.waitForBackgroundJavaScript(3000);
// Click on search
HtmlAnchor anchor = (HtmlAnchor) page.getByXPath("//*[@id=\"fbox_gridCampaNoi_search\"]").get(0);
page = anchor.click();
webClient.waitForBackgroundJavaScript(3000);
System.out.println(page.asText());
}
Download pdf:
try
{
InputStream is = _link.click().getWebResponse().getContentAsStream();
File path = new File(new File(DOWNLOAD_PATH), _regNumber);
if (!path.exists())
{
path.mkdir();
}
writeToFile(is, new File(path, _regNumber + "_pdfs.zip"));
}
catch (Exception e)
{
e.printStackTrace();
}
}
The problem:
The first car works okay, pdf is downloaded, but as soon as I search for a new car, when I get to this line:
page = page.getElementById("search_gridCampaNoi").click();
I get this exception:
Exception in thread "main" java.lang.ClassCastException: com.gargoylesoftware.htmlunit.UnexpectedPage cannot be cast to com.gargoylesoftware.htmlunit.html.HtmlPage
After debugging, I've realized that the moment I make this call:
InputStream is = _link.click().getWebResponse().getContentAsStream();
the return type of page.getElementById("search_gridCampaNoi").click() changes from HtmlPage to WebResponse, so instead of receiving a new page, I'm receiving again the file that I already downloaded.
A couple of screenshots of the debugger showing this situation:
First call, return type OK:
Second call, return type changed and I no longer receive a HtmlPage:
Thanks in advance!
回答1:
Just in case someone encounters the same problem, I found a workaround.Changing the line:
InputStream is = _link.click().getWebResponse().getContentAsStream();
to
InputStream is = _link.openLinkInNewWindow().getWebResponse().getContentAsStream();
seems to do the trick. Im having problems now when doing several iterations, sometimes it works, sometimes it doesn't but at least I have something now.
来源:https://stackoverflow.com/questions/8049947/htmlunit-cant-retrieve-page-after-downloading-a-file