Invoke PDF, Server returned HTTP response code: 400 - http

Question

English is not my native language; please excuse typing errors.
Hope I improved the question.
I start a Script over Selenium, automated testing, WebDriver.
I perform a Link on HTML-Page
This link creates a new Browser Tab
This BrowserTab display a PDF/A Standard Document
I want to parse the PDF an verify its content
After HttpURLConnection I got Hypertext Transfer Protocol (HTTP) response status code: 400
and parsing the InputStream can not be done.
Over localhost it can be done.
Also I can hit link "curent URL" without any problems.
Selenium v2.45.0
Tested on IE 9 and Firefox 39.0.
How can I examine the problem?
I read about HTTP response code: 400
But didn't find solution for my problem
Could it be a redirect-problem?
Thank you
Here is my code:
public class httperrorStack {
public static void main ( String[] args )
{
// Selnium WebDriver
WebDriver driver = null;
//driver = new FirefoxDriver();
// Test with Browser IE 9 same Problem withFirefox 39.0
System.setProperty("webdriver.ie.driver","C:\\dir\\IEDriverServer.exe");
driver = new InternetExplorerDriver();
String baseUrl = "http://##.###.###.##:#####/wps/portal"; //ATU2
// launch direct to Base URL
driver.get(baseUrl);
// launch to Documentlink: opens PDF/A-Document in a new Browser Tab
driver.findElement(By.xpath("//a[#title='document_link']")).click();
//Get all the window handles in a set
Set <String> handles =driver.getWindowHandles();
Iterator<String> it = handles.iterator();
//iterate through windows
while (it.hasNext()){
String parent = it.next();
String newwin = it.next();
driver.switchTo().window(newwin);
URL url = null;
try {
// The CurrentURL of the documentlink
// url = "http://##.###.###.###:#####/wps/myportal/dirname/dirname/dir-name/!dir/p/b1/about50characters/In"
url = new URL(driver.getCurrentUrl());
} catch (MalformedURLException e1) {
e1.printStackTrace();
}
// verify connection
HttpURLConnection connection = null;
HttpURLConnection httpConn = (HttpURLConnection)connection;
try {
httpConn = (HttpURLConnection)url.openConnection();
} catch (IOException e1) {
e1.printStackTrace();
}
InputStream is = null;
// Response Code = 400
try {
if (httpConn.getResponseCode() >= 400) {
is = httpConn.getErrorStream();
// httpConn.getResponseCode() = 400
//httpConn.getErrorStream() = "sun.net.www.protocol.http.HttpURLConnection$HttpInputStream#1d082e88"
} else {
is = httpConn.getInputStream();
}
} catch (IOException e1) {
e1.printStackTrace();
}
try{
connection = (HttpURLConnection)url.openConnection();
InputStream is2;
if (connection.getResponseCode() >= 400) {
is2 = connection.getErrorStream();
//connection.getErrorStream() = "sun.net.www.protocol.http.HttpURLConnection$HttpInputStream#60704c"
} else {
is2 = connection.getInputStream();
}
}
catch (Exception e){
e.printStackTrace();
}
BufferedInputStream fileToParse = null;
try {
fileToParse = new BufferedInputStream(
url.openStream());
} catch (IOException e) {
e.printStackTrace();
// output of StackTrace
/*java.io.IOException: Server returned HTTP response code: 400 for URL: http://##.###.###.##:#####/wps/redirect
at sun.net.www.protocol.http.HttpURLConnection.getInputStream0(Unknown Source)
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(Unknown Source)
at java.net.URL.openStream(Unknown Source)
at mypackage.httperrorStack.main(httperrorStack.java:134)*/
}
// Close Window
driver.close();
driver.switchTo().window(parent);
driver.quit();
// exit the program explicitly
System.exit(0);
}
}
}