HttpURLConnection and headers.

I want to send an XML document to a HttpServlet and get a new one back. I plan to send it using the POST method however, in order to enclose the document in the request I need to set the Entity-Headers.. I can't really se how I would do this with HttpURLConnection. Can I modify the headers that HttpURLConnection produce at all?
Of course, I could just use a regular URLConnection and pass all headers manually but it would be nice to avoid that.

Well, thats not the problem...
I need to send the whole document in the Request in order to get a response object with the other document. But if I do something like this:
HttpURLConnection conn = (HttpURLConnection)url.openConnection("foo");
conn.setContentType("text/plain");
conn.setDoOutput(true);
PrintWriter out = new PrintWriter( dataConn.getOutputStream() );
out.write("blah");
out.close();
then I can't call setDoInput() and open an inputstream and read the response. I get and exception saying the connection is already open. This leads me to the conclusion that when I call the SetDoInput it opens a new Connection which is not possible since it is already open.
When Is the request actually sent and how do I modify indivdual headers in the request?

Similar Messages

Problem with HttpURLConnection and HttpSession.

Hi,
Problem with HttpURLConnection and HttpSession.
I created a HttpSession object in my main class and then called a URL via HttpURLConnection.
I tried to access the same session object from the servlet called by the URL . but the main session
is not returned a new seperate session is created.let me know how can we continue the same session in
the called URL also which is created in main class.
Thanks
Prasad

You are not supported to create a HttpSession by java client. Only J2EE web container can create it.

Change table size and headers in type def cluster

Is is possible to change a table size and headers that is inside a type def cluster?
I have a vi that loads test parameters from a csv file. The original program used an AC load so there was a column for power factor. I now have to convert this same program to be used with a DC load, so there is no power factor column.
I have modified to vi to adjust the "test table" dynamically based on the input file. But the "test table" in the cluster does not update it's size or column headers.
The "test table" in the cluster is used through out the main program to set the values for each test step and display the current step by highlighting the row.
Attachments:
Load Test Parms.JPG ‏199 KB
Table Cluster.JPG ‏122 KB

Nevermind, I figured it out...
I was doing it wrong from the start, in an effort to save time writing the original program I simply copied the "test table" to by type def cluster. This worked but was not really as universal as I thought it would be, as the table was now engraved in stone since the cluster is a type def.
I should not have done that, but rather used an array in the cluster and only used the table in the top level VI where it's displayed on the screen.

HttpURLConnection and URLConnection

hi,
what's the difference between HttpURLConnection and URLConnection ?
When should I use the first and when the second one ?
thanks

The Javadoc shows the relationship. Cast a URLConnection to an HttpURLConnection when the URL protocol is HTTP.

Suddenly my past emails won't load. Missing body and headers, just blank. How can I fix this?

I have email listings, and even double clicking then that opens a new tab is blank. It is affecting emails from April 19 and earlier to all I have in listing back to 2009. I cannot access any of the actual email bodies and headers also do not load. I tried to compact folders. Nothing. Recent emails arriving since April 19, 2015 are coming in fine and I can load them but none of the previous ones. Please help. I am missing valuable information not having these emails open able.

<blockquote>
even double clicking then that opens a new tab is blank.
</blockquote>
Possibly there's some sort of corruption. You can try to rebuild the index file of the troubled folder.
Right-click the folder - Properties - Repair Folder
In best case this could restore everything to normal. In worst case this could erase messages back to 2009, depending on the state of corruption.
So before doing anything make sure to have a backup of your profile folder.
http://kb.mozillazine.org/Thunderbird_:_FAQs_:_Backing_Up_and_Restoring
<blockquote>
I have had 2 critical crashes or corrupt files and seriously concerned after so many years of Thunderbird being so stable.
</blockquote>
Then you hopefully learned from that and you did create backups on a regular basis.
<blockquote>
I want to know what happened ...
</blockquote>
The most common reason for corruption is anti-virus software writing to Thunderbird files when it shouldn't.
<blockquote>
... and also if there is any way to recover.
</blockquote>
There is no guarantee. But if you have a backup then there is no problem.

What happened to my Backgrounds and Headers in my tools after Upgrade to XI?

Hi,
I had several custom backgrounds and headers & footers saved in my Acorbat X, upgraded to XI and now they are gone. How can I get them back?

Hi capt360,
Please check the location folder of these custom backgrounds / headers & footers and see if any of these are still present.
Have you added these backgrounds and customised the navigator (.nav) files?
You can refer the following doc to check the location of the .nav files : http://blogs.adobe.com/pdfdevjunkie/adding-themes

Help With HttpURLConnection and PHP

I can connect to a site with HttpURLConnection but i need to access a link FROM that site.
Ex: www.hangman/index.php
I need to get a link like www.hangman/index.php?letter=a
It will only display the letter if you go from www.hangman/index.php and click on the letter. But how do i do that with HttpURLConnection.
I think you have to use the POST , but it doesnt work.
Thanks.

That's probably because the site uses cookies to maintain a session.
The cookie's name is PHPSESSID, so I'm guessing this is a standard PHP session maintenance system (I haven't worked with PHP much...).
So if you want to create a java app that will play hangman from that site, it looks like you'll have to handle cookies to keep the session active between accesses. So you'll grab the cookie from the response headers in the first connection, and then send it to the server in the request headers in subsequent connections. The cookie may remain the same throughout the session, or it may change on each connection; I don't know.
I did a quick google and found this:
http://jcookie.sourceforge.net/
I haven't used it myself, but it looks useful. Unless you're doing this as a learning exercise, it's probably easier to use this than to wrote your own cookie code.

HttpURLConnection and HtmlUnit

Hello,
I am using these commands to get a webpage from my in-house webserver:
String urlStr = "http://localhost/welcome.jsp";
URL url = new URL(urlStr);
HttpURLConnection ucon = (HttpURLConnection)url.openConnection();
ucon.connect();
InputStreamReader isr = new InputStreamReader(ucon.getInputStream());
BufferedReader in = new BufferedReader(isr);
I then read the file line by line, searching the text for this input tag:
<input type=hidden name=pagecode value=123>
Is there any easier way to get the value of this hidden variable?
Does the HttpURLConnection have some way of extracting hidden values directly?
Thank you for helping.

I put the htmlunit-2.11.jar file in the web-inf/lib folder.
I added this line to my standard java file:
import com.gargoylesoftware.htmlunit.WebClient;
I tried to rebuild the java file and got this error:
cannot access com.gargoylesoftware.htmlunit.WebClient;
bad class file web-inf/lib/htmlunit.jar
class file has wrong version 50.0, should 49.0
please remove or make sure it appears in the correct subdirectory of the classpath
Any suggestions are greatly appreciated.

HttpURLConnection and HEAD/GET methods

I am attempting to validate whether an HTML page exists or not.
I have found that, for about 7% of the pages checked, HEAD and GET methods return different response codes.
I have structured my code such:
1) make initial check using HEAD method
2) for non valid (200) response codes, recheck the page using the GET method.
In this case about 75% of the pages that failed using the HEAD method will work when using the GET method.
So, I guess my questions are:
1) Does anybody know why HEAD/GET return different response codes?
2) Does anybody know a better way to check if a page exists?
Here is the sample program I am using with a few URLs that exhibit this behaviour:
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.InetAddress;
import java.net.URL;
import java.net.UnknownHostException;
public class Internet
     private final static String DEFAULT_LOCAL_HOST = "127.0.0.1";
     private URL url;
     private HttpURLConnection http;
     private int responseCode;
     private String responseMessage;
     public Internet(URL url)
          this.url = url;
     public boolean isValid()
          try
               // Make first attempt using a HEAD request
               http = (HttpURLConnection)url.openConnection();
               http.setRequestMethod( "HEAD" );
               http.connect();
               System.out.println( "head: " + http.getResponseCode()
               + " : " + http.getResponseMessage() );
               // GET seems to do a better job, try again
               if ( http.getResponseCode() != HttpURLConnection.HTTP_OK)
                    http = (HttpURLConnection)url.openConnection();
                    http.setRequestMethod( "GET" );
                    http.connect();
                    System.out.println( "get: " + http.getResponseCode() );
               responseCode = http.getResponseCode();
               responseMessage = http.getResponseMessage();
               if (http.getResponseCode() == HttpURLConnection.HTTP_OK)
                    return true;
               else
                    System.out.println( http.getResponseMessage() );
                    return false;
          catch (IOException e)
               responseCode = -1;
               responseMessage = e.getMessage();
               System.out.println( e );
               return false;
     public static void main(String[] args)
          throws Exception
          URL url = new URL( "http://www.trca.on.ca" );
          Internet internet = new Internet( url );
          System.out.println( internet.isValid() );
          url = new URL( "http://school.discovery.com/sciencefaircentral" );
          internet = new Internet( url );
          System.out.println( internet.isValid() );
          url = new URL( "http://www.amazon.com" );
          internet = new Internet( url );
          System.out.println( internet.isValid() );
}

Using my sample program:
1) about 3K of data is transferred
2) it runs in about 8 seconds
Using InputStream in = http.getInputStream():
1) about 73K of data is transferred
2) it runs in about 15 seconds
Using the getInputStream() method causes the entire file to be transmitted (even though I don't use any read() methods). I don't care about the data.
I want the check to be as fast as possible which is why I use the HEAD method. It doesn't transfer the contents of the file. But why in some cases does it show a response code other than 200?

HttpURLConnection and the killer Pound (#)

I'm trying to create a part of my application that posts data to an ASP page (on an affiliate's web site).
Originally, I was using the following code to post the data:
URL url = new URL(sPostURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
// include fields to post
conn.setRequestProperty("address", sAddress);
conn.setRequestProperty("ste/apt#", sApt);
DataOutputStream dos = new DataOutputStream(conn.getOutputStream() );
dos.writeBytes("");
dos.close();
// Retrieve response
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String sNewLine = in.readLine();
String sResp = "";
while (sNewLine != null) {
sResp += sNewLine;
sNewLine = in.readLine();
in.close();Which worked at first, but then when I went back to the code, I must have made a change because it no longer seems to post the data (sAddress and sApt) to the page. So after researching the topic in the forums, I switched to using a tokenized string to store my post data:
URL url = new URL(sPostURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
conn.setDoInput(true);
conn.setDoOutput(true);
conn.setUseCaches(false);
DataOutputStream dos = new DataOutputStream(conn.getOutputStream() );
// include fields to post
String sRequest = "&address=" + sAddress; // BUILD DATA STRING (NEW)
sRequest += "&ste/apt#=" + sApt; // BUILD DATA STRING (NEW)
dos.writeBytes("");
dos.close();
// Retrieve response
BufferedReader in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
String sNewLine = in.readLine();
String sResp = "";
while (sNewLine != null) {
sResp += sNewLine;
sNewLine = in.readLine();
in.close();which posts the data fine, but the pound sign (#) causes the server to return a response code 500. I can't find an easy way to escape the pound sign. I've even tried building the string using the URL encoded value (%23) but it still causes problems. Does anyone have any suggestions? Was I correct in abandoning the first method? if anyone has any guidance I would be very grateful.

I think the first method is more clean, but if you want to use the second one, you should put your request string through a URLEncoder to encode the string first.
--lichu

HttpURLConnection and bandwidth

I have written a program which downloads files from net using the HttpURLConnection class.
I want to specify the percentage of bandwidth that should be used for downloading the files, so that it does not slow down by other net surfing work.
Can anybody suggest me a way to do this.
Thank u

That's not something you can control via Java.
The only way you could control that is thru some network hardware, or, if the server is yours, you could set a header in the request and the server could take that as a clue to throttle the data it's going to send out. But otherwise, URLConnection class itself will not be able to do anything.

HttpUrlConnection and codification

Hello, I am trying to open a connection to a webpage that is writen in greek (using utf8), but when I try to see the page in my JSP, I don't see well the greek characters. Is my code wrong? maybe is the server configuration?
I have no idea. I try some encode, but nothing changes.
Iam using java 5.0 and tomcat 5.5.
My code:
String url = "http://www.google.gr";
URL u = new URL (url);
HttpURLConnection urlc = (HttpURLConnection)u.openConnection ();
response.setContentType("text/html;charset=UTF-8");
urlc.connect ();
URLConnection.getInputStream()
String line;
BufferedReader br = new BufferedReader (new InputStreamReader (urlc.getInputStream ()));
while ( (line = br.readLine ()) != null ) {
out.write(line);
br.close ();
urlc.disconnect ();
Thanks a lot.
isaac.

Well, you aren't specifying the encoding on your InputStreamReader, so it would be using some other encoding instead. There may be other problems but fix that one first.

HttpURLConnection and redirect

Hello,
I need help with this. I have on server xml page with some data, but before I get this page, I must login to server. With my code, I reach only redirect page. How I can login and get response after redirect?
Here is the function for communication:
package qpconnector;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
public class ServerConnect {
    private String defaultServer =
            "http://10.0.5.55/login/login.action?username=InstallAdmin&password=&" +
            "page=/touchscreens/mainDisplay.qsphtml";
    public void connectToServer () {
        try {
            URL url = new URL(defaultServer);
            URLConnection connection = url.openConnection();
            HttpURLConnection httpConn = (HttpURLConnection) connection;
            httpConn.setDoInput(true);
            httpConn.setDoOutput(true);
            InputStream is = httpConn.getInputStream();
            StringBuffer sb = new StringBuffer();
            int read;
            while ((read = is.read()) != -1) {
                sb.append((char) read);
            System.out.println (sb.toString());
        } catch (MalformedURLException ex1) {
            ex1.printStackTrace();
        } catch (Exception ex) {
            ex.printStackTrace();
    public static void main (String[] args) {
        ServerConnect sc = new ServerConnect();
        sc.connectToServer();
}

ProjectMoon wrote:
malcolmmc wrote:
By default java.net.URL connections manage cookies automatically.It appears that it will provide you with Cookie objects from the server when you make the connection. However, when you make a new connection, you will have to send your cookies with it. This is because of the way HTTP works. If that is incorrect, I apologize.It will return cookies received from a particular domain to that domain, which is generally all you need. Cookies always originate at the server end.
>
Edit: [Ah ha.|http://blogs.sun.com/CoreJavaTechTips/entry/cookie_handling_in_java_se] There is new stuff in Java 6 for cookies.
There is, it makes the cookie business more manageable, but the basic cookie mechanism is already there, at least in 1.5, it's just a lot more tedious if you want to do something complicated, like maintain more than one cookie jar in the JVM.

HttpURLConnection and DataInputStream

I posted this in the Conventional & Interruptable IO forum, but thought it might be better off here....
I'm having a strange issue with this piece of code. The input stream coming in is quite predictable and I know that this loop will only iterate twice. Once for less than 1024 bytes, and the next returns -1. The problem I'm having has to do with the second iteration. The in.read(bary); line takes around 75 seconds just to get that -1 so we can break out of the loop. I don't understand how the first read is so fast, and the second one is so slow. Any thoughts?
1 URL url = new URL("http://xyz");
2 HttpURLConnection con = (HttpURLConnection)url.openConnection();
3 DataInputStream in = new DataInputStream( con.getInputStream() );
4 StringBuffer httpResponse = new StringBuffer();
5 byte[] bary = new byte[1024];
6 while (true) {
7 int bytesRead = in.read(bary);
8 if (bytesRead <= 0) {
9 break;
10 }
11 httpResponse.append(new String(bary, 0, bytesRead));
10 }//end while
I also want to mention that this bit of code runs in J2EE apps that are deployed to 5 different environments, one of those being production which is heavly hit. In only one of these am I having the issue...not production :) . They're running on Solaris 8, sun's sdk 1.4.2_3, weblogic 8.1. Also, I've run the exact same code making this call and I know that the app on the other end is responding fast...we've also verified this using the webserver's access log.
Thanks for reading,
-Jon

The -1 check is in the while loop, it's just not indented very well. The loop starts on line 6, and ends on 10. I mentioned the data is predicatable. On the first call to read I know that I'm reading all the data that the stream has to offer, the second time i read returns -1. I also know this because The actual code has debug statements that tell me how many times it loops, and how long it takes to perform the read in millies. 100% of the time it loops twice, and 100% of the time the read that results in -1 takes 75 seconds.
Maybe i misunderstood what you were saying? Any thoughts would be greatly appreciated.
Message was edited by:
jTosca
Message was edited by:
jTosca

HttpURLConnection and cookies!!

hello evrybody,
i want to write a program which connect to a URL and load some data from there. but the problem is that site writes cookies you will only receive an hint to allow cookies. How can i write a program or simulate a client that accepts cookies to have finaly the required data.
the Programm i am using doesn�t work. Here is a snippet:
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setDoOutput( true );
con.setDoInput( true );
if (!con.getAllowUserInteraction()) con.setAllowUserInteraction( true );
con.setFollowRedirects( true );
BufferedInputStream br = new BufferedInputStream(con.getInputStream());
byte[] c = new byte[5000];
int read;
read = br.read(c,0,5000)

I believe it would be something like the following:
URL url = new URL(...);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setRequestProperty("Cookie", "your cookie here");
conn.connect();

HttpURLConnection and headers.

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