URLConnection vs sockect connection

I need to connect to a dataserver
it seems i have two choice,
I can use
URL myURL = new URL("http://server:port#/../.... " )
URLConnection mycon = myURL.openConnection( ) ;
or I can use socket connection by passing server name
and prot number.
Here is my question
What is the pro and con of this two way.
if my url is like this,
http://server:port#/mypage.html?param=value
Is there anyway I can pass the param value pair to the server by using socket connection ?
Any comment will be helpful
Thanks !

The short answer is that you can send the query string out over a socket connection. Heres the steps ( in very pseudo code ) :
// get a socket
Socket client = new Socket( hostName, port );
// get a printwriter - this is neede because java speaks
// in Unicode but webservers require ascii :
Printwriter out = new Printwriter (
client.getOutputStream() ) ;
// now you have to use the printwriter to output ALL
// the HTTP headers to the webserver - they are not all
// shown here - AND you have to make sure the
//structure of the headers + message body ( ie for POST)
//complies to HTTP ( rfc 1945 for version 1.0 )
// here is the first line you will need :
out.println(
"GET /example/page.jsp?name=value HTTP/1.0");
On the URL side of the fence the pros are that you don't generally have to mess around with all the low level protocol dependent stuff ( liek the headers ) .

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Please, it's quite urgent...
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We have written a utility whick keeps monitoring the
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sessions.
How do I user URLConnection or similar object so that
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server.
Thanks for the help in advance!Dear sir,
Do you solve your question in this topic?
I have similar problem.

URLConnection erratic behavior

I am using a URLConnection object to connect to apache Tomcat. About half the time it works fine, and the other half tomcat throws an exception saying the connection was aborted by Peer (which I am assuming is my connection object).
It sounds as if the underlying socket times out, or something like that. But there is no way to set the timeout using the URLConnection object. The following is the code I am using to connect:
HttpURLConnection uconn = (HttpURLConnection) url.openConnection();
uconn.connect();
InputStream is = uconn.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
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StringBuffer contentBuffer = new StringBuffer("");
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You can set the timeout on client side tcp socket connections with Socket.setSoTimeout(), but unfortunately I'm pretty sure you can't get to the socket connection in any form or fashion from HttpURLConnection. It's because your http connection may not actually be running on top of tcp sockets. For example, several mobile phone networks provide http connections to their Java enabled phones, but the http connections don't run on top of tcp.
If you're not making any advanced use of http, you could write your own http client in a couple hours and use it to connect instead.
I'd be glad to hear if anybody knows a better workaround. If you don't hear anything, I would suggest filing an RFE with Sun.
God bless,
-Toby Reyelts

Change url URLConnection

I want to connect from an applet to a servlet with URLConnection. There are 2 ways to connect: in the beginning of each session you connect to the applet to get a list of drawn shapes. I create an URLConnection object and connect to the servlet. I go into the doGet-method, retrieve the values from a database and returns an arraylist. I use the doPost method to save new shapes.
When i delete a shape from the canvas, i want to return to the doGet method by adding a parameter to the url. E.g ../ShapeServlet?shapeid=20. The problem is, the url is correct, but the URLConnection object keeps using the url from the beginning of the session (without the parameter). I use 2 seperate objects so it's kinda weird he keeps connecting to the servlet with the first url. I also tried to do it hard-coded, but it doesn't work either.
Here's the code:
Load the shapes from the applet:
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          try{
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               URLConnection con = servlet.openConnection();
               con.setUseCaches(false);
               inputFromServlet = new ObjectInputStream(con.getInputStream());
               ArrayList lijst = (ArrayList) inputFromServlet.readObject();
               inputFromServlet.close();
               return lijst;
          catch(MalformedURLException e){ e.printStackTrace(); }
          catch(IOException e){ e.printStackTrace(); }
          catch(ClassNotFoundException e){ e.printStackTrace(); }
          return null;
     }Delete a shape:
     /** Shape weggooien */
     public void deleteShape(int shapeid)
          try{
               String a = "http://PCPST2:8080/AppletViewer/ShapeServlet?shapeid=" + shapeid;
               URL servlet = new URL(a);
               System.out.println("DELETESHAPE: " + a);
               URLConnection connectionTwo = servlet.openConnection();
               connectionTwo.setUseCaches(false);
          catch(MalformedURLException e){ e.printStackTrace(); }
          catch(IOException e){ e.printStackTrace(); }
     }

it seems that deleteShape() doesn't connect to the servlet. Is it possible that >the servlet rejects the connection?No, he simply doesnt connect :), wierd behaviour, but that's how the default implementation of URLConnection and HttpURLConnection works.
The following is from javadocs
The connection object is created by invoking the openConnection method on a URL.
The setup parameters and general request properties are manipulated.
The actual connection to the remote object is made, using the connect method.
The remote object becomes available. The header fields and the contents of the remote object can be accessed.
You havent used the connect() method in your deleteShapes() method.
Hang on, even if you use it, it wouldnt connect to the Servlet.
I did some reading up on this and again javadcos has this to say about the connect() method
Operations that depend on being connected, like getContentLength, will implicitly perform the connection, if necessary.
So what I did was forced connect() by getting the input stream from the connection.
In your code, though the deleteShapes() method doesnt have anything to read from the Servlet, create a reader and make a dummy readLine() call.
You would see that it connects now. Add the code below to your deleteShapes() method.
        InputStreamReader reader = new InputStreamReader(conn.getInputStream());
        System.out.println((new BufferedReader(reader)).readLine());
         //this will return null, coz there's nothing to be read, and
         //yet it would ensure connection.Hope this helps,
ram.

URLConnection writing a PDF file

Hi all,
Does anybody know a way to write a URLConnection where the connected Servlet writes a PDF file?
I mean, Servlet1 connects to Servlet2 and Servlet2 writes a pdf file to the connection and Servlet1 has to write to the browser.
Thank you,
Denis.

Hi Denis,
The following are the steps you need to follow in your servlet2.
StringBuffer output = new StringBuffer();
URL firstServletURL = new URL("the first url");
URLConnection firstServlet=first.openConnection();
firstServlet.setDoInput( true );
firstServlet.setUseCaches( false );
BufferedInputStream in = new BufferedInputStream (firstServlet.getInputStream() );
int oneByte;
while(( oneByte = in.read( ) ) >= 0)
output.append( (char) oneByte );
in.close();
out.println(output.toString());
thanks,
Sriram

Establishing connection...

When I use
URL url = new URL("http://xxx.xxx.xxx.xxx:1234");
URLConnection urlC = url.openConnection();
InputStream is = urlC.getInputStream();
is there any way to know if the host is really there without using exceptions?
Thanks in advance

There is a way using the JDK 1.5 InetAddress.isReachable() method to determine whether the host is there. However that doesn't tell you:
(a) whether there is an HTTP server in it,
(b) whether it will accept connections from you,
(c) whether it will all still be there when you come to make the URLConnection.
Catching connect exceptions is really the best solution, why do you need another one?

HttpUrlConnection's setRequestProperty() doesn't work

Hi,
I am trying to set the request properties of a HttpUrlConnection to specific settings before I download the given page. however, the response code is 200(OK) for pages that have different property from what I set. For Example, I set
connection.setRequestProperty("Accept","image/jpg");
connection.setRequestProperty("Accept-charset","utf-8");
for the connection and ask for the page with accept :text/html and accept-charset:iso-8859-1, but the response is 200(Ok).
can anybody tell what is wrong with my code, the code is as follows:
import java.net.URL;
import java.net.URLConnection;
import java.net.HttpURLConnection;
import java.util.Properties;
class Headok
private int code;
     String proxy = "proxy.xxx.xxx.xx";
     String port = "8080";
public boolean headOk(URL HeadUrl)
          try
          Properties systemproperties = System.getProperties();
          systemproperties.setProperty("http.proxyHost",proxy);
          systemproperties.setProperty("http.proxyPort",port);
          //URLConnection HeadUrl = new URLConnection(url);
          HttpURLConnection connection = (HttpURLConnection)HeadUrl.openConnection();
          connection.setDoOutput(true);
          connection.setRequestMethod("HEAD");
          connection.setRequestProperty("Accept","image/jpg");
          connection.setRequestProperty("Accept-charset","utf-8");
     connection.setRequestProperty("From","[email protected]");
connection.setRequestProperty("Connection","Keep-Alive");
          connection.connect();
          code=connection.getResponseCode();
          //System.out.println(code);
               if (code==connection.HTTP_OK)
                    return true;
catch (Exception e)
     return false;
return false;
public static void main (String args[]) throws Exception
     Headok head = new Headok();
boolean k=     head.headOk(new URL("http://news.bbc.co.uk/"));
     if(k==true)
          System.out.println("ok");
     else{
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}

Dear ethiio,
First a big thanks for your keen in knowing this problem. Please help me in this issue. I am breaking my head for the past four days. Here i explain it in detail... All the sites i have referred does the same and i am also following the same but not getting the solution.
SCENARIO:
I want to mimic a browser using the java code. i will supply the first page url then the java code should read the html of the given url. then the second url and it should do the same.... then the third url....fourth and so on...
Problem:
The code works fine... but the problem is : when i give the second url i am getting a cookie in the response header. I am able to read header and get the "Set-Cookie" value. I am using setRequestProperty("Cookie",cookie) to set the read value of cookie to next request. But instead of getting the html of the url i supplied i am gettin the html of "ERROR PAGE" which contains the message as follows: "Cookies Should be enabled for this service, Please enable cookies in your browser" i dont know where i am going wrong... Please help me to fix this problem
SOURCE CODE:
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.MalformedURLException;
import java.net.URL;
public class UrlCheck
     int stepCount=1;
     int fileSuffix=1;
     int cookieSuffix=1;
URL url = null;
     BufferedReader bufferedReader = null;
     boolean isCookieFound=false;
     String copyCookie=null;
     public static void main(String[] urls) throws MalformedURLException,IOException
          System.getProperties().put("proxySet","true");
          System.getProperties().put("proxyHost","a.b.c.d");// a,b,c,d is not the actual value
          System.getProperties().put("proxyPort","X");//X is not the actual value
          UrlCheck readHtml = new UrlCheck();
          while(readHtml.stepCount<6)
          readHtml.url=new URL(readHtml.urlDesigner());
          readHtml.cookieAndContent();
     public String urlDesigner()
          String url=null;
          switch(stepCount)
               case 1:
                    url="URL 1";
                    stepCount++;
               break;
               case 2:
                    url="URL 2";
                    stepCount++;
                    break;
               case 3:
                    url="URL 3";
                    stepCount++;
                    break;
               case 4:
                    url="URL 4";
                    stepCount++;
                    break;
               case 5:
                    url="URL 5";
                    stepCount++;
                    break;
          return url;
     public void cookieAndContent() throws IOException
          int n=1;
          String cookie=null;
          String temp=null;
          boolean done = false;
          FileOutputStream fileOutputStream = new FileOutputStream("D:/Cookie/Cookie"+cookieSuffix+".txt/");
          DataOutputStream dataOutputStream= new DataOutputStream(fileOutputStream);
          FileOutputStream fileOutputStream1 = new FileOutputStream("D:/ReadHtml/Page"+fileSuffix+".txt/");
          DataOutputStream dataOutputStream1= new DataOutputStream(fileOutputStream1);
          HttpURLConnection connection = (HttpURLConnection) (url.openConnection());
          if(isCookieFound)
               System.out.println("----------"+copyCookie+"----------");
               connection.setUseCaches(false);
               connection.setDefaultUseCaches(false);
               connection.setDoInput(true);
               connection.setDoOutput(true);
               connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
          connection.setRequestProperty("Cookie",copyCookie);
          PrintWriter pw = new PrintWriter(connection.getOutputStream());
          pw.flush();
               pw.close();
          connection.connect();
          InputStream ip = connection.getInputStream();
          /**************Header Value Getter************************/
          while (!done)
               String headerKey = connection.getHeaderFieldKey(n);
          String headerVal = connection.getHeaderField(n);
          if (headerKey!=null || headerVal!=null)
          //System.out.println(headerKey+"="+headerVal);
          dataOutputStream.writeBytes(headerKey+"+"+headerVal);
          else
               done = true;
               cookie=connection.getHeaderField("Set-Cookie");
               //copyCookie=cookie;
                    if(cookie!=null)
                         int index = cookie.indexOf(";");
                         if(index >= 0)
                              isCookieFound=true;
                              cookie = cookie.substring(0, index);
                              copyCookie=cookie;
                              System.out.println("##########"+cookie+"##########");
                              dataOutputStream.writeBytes("****************"+cookie+"****************");
          n++;
          cookieSuffix++;
          //System.out.print(copyCookie);
          /**************Content Value Getter************************/
          int ch;
          char value;
          while((ch=(ip.read()))!=-1)
                         value=(char)ch;
                         //System.out.print(value);
                         dataOutputStream1.writeBytes(String.valueOf(value));
          fileSuffix++;
          ip.close();
          connection.disconnect();
          System.out.println("*********"+isCookieFound+"*********");
Message was edited by:
Lokee

Servlet with CGI

hello,
We have an applet that execute a cgi program and now we want to replace that applet with a servlet executing the same cgi.
Does anyone know how i can execute my CGI bin with a servlet or javabean?
Thanks and good luck
minhqt

hi,
Maybe i didn't explain myself clearly, i would like to know how i can use java urlconnection class to connect my java servlet to cgi. What i'm trying to do is create a jsp page that include a servlet and this servlet pass selected parameters from my jsp page to my existing cgi code.
so the question here is 1)how do i send these parameters to my cgi and 2) how can i receive cgi output to later on display using jsp.
While doing these what are some errors handling code do i need to know.
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minhqt

Calling servlet through HttpURLConnection

hi guyz ....
I am trying to call a servlet, hosted on Tomcat/4.0.3. It is accepting two parameters. I am using the following program to call it, but it is continuously throwing exception Exception in thread "main" java.io.FileNotFoundException: http://202.141.230.246:8080/examples/servlet/AServlet. When I paste the above same url in browser, it works fine, also other servlets at the same location are working fine from my program and browser. For your convenience, the effective part of the code is given below:
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      URLConnection connection = (URLConnection) url.openConnection();
      //connection.setRequestMethod("POST");
      connection.setDoOutput(true);
      PrintWriter out = new PrintWriter(connection.getOutputStream());
      // encode the message
      String name = "s="+URLEncoder.encode("Qusay Mahmoud");
      String email = "name="+URLEncoder.encode("[email protected]");
      // send the encoded message
      out.println(name+"&"+email);
      out.close();
      BufferedReader in =
                new BufferedReader(new InputStreamReader(connection.getInputStream()));
      String line;
      while ((line = in.readLine()) != null)
         System.out.println(line);
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Any help will be of great value.
Raheel.

hi again .... a slight change in code fragment.
plz help !!!!
URL url = new URL("http://202.141.230.246:8080/examples/servlet/AServlet");
   HttpURLConnection connection = (HttpURLConnection) url.openConnection();
   connection.setRequestMethod("POST");
   connection.setDoOutput(true);
   PrintWriter out = new PrintWriter(connection.getOutputStream());
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   String name = "id="+URLEncoder.encode("Qusay Mahmoud");
   String email = "name="+URLEncoder.encode("[email protected]");
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   out.println(name+"&"+email);
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        System.out.println(line);
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Plugin hangs when prompting for network password

Hi all,
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The plugin hangs after displaying the dialog box for the
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No exception is shown.
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Code sample here :
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_httpsFlag = false;
catch (Exception e) {
try {
url = new URL(reqHttps);
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is = conn.getInputStream();
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e2.printStackTrace();
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Just for the record :
I sorted this one by creating a dummy connection before instanciating the graphical components of the applet.
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No Sound in Fedora Linux with flash-plugin-9.0.115.0

Hi ... I've checked everything I think I can ... I have alsa
configured and that works ... confirmed with mplayer:
mplayer -ao alsa:device=INTERNAL
http://wnyc2.streamguys.com:80
Yet no sound from flash ???
Flash 7 was working fine ....
Thoughts???

kcell,
thanks for the reply. Actually you are a bit ahead of me. I
have a single web-server and I'm not actually trying to cross
domains! However, the security advice says (page 4 of the link I
gave in my original post)
"A URL policy file authorizes data loading from its own HTTP,
HTTPS, or FTP server, whereas a socket policy file authorizes
socket connections to its own host."
So because I'm using a socket connection I still need a
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<site-control
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Applying default meta-policy 'all'. This configuration is
deprecated. See
http://www.adobe.com/go/strict_policy_files
to fix this problem.
Sory about the excessive waffle!

SocketTimeoutException: Read timed out

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I am using Axis1.4. I write a build script and created the client stubs from WSDL, which generated the following files for me:
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customer.CustomerWS.java
customer.CustomerWSBindingImpl.java
customer.CustomerWSBindingSkeleton.java
customer.CustomerWSBindingStub.java
customer.CustomerWSLocator
customer.types.Customer.java
customer.types.CustomerAddress.java
customer.types.GetCustomerElement.java
customer.types.GetCustomerResponseElement.java
customer.types.GetTestFaultElement.java
customer.types.GetTestFaultResponseElement.java
customer.types.OraIntException.java
Then I wrote a client application with a main method like this:
CustomerWSBindingStub stub = new CustomerWSBindingStub();
stub.setUsername("test");
stub.setPassword("test");
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stub.setTimeout(60000);
GetCustomerElement element = new GetCustomerElement("1");
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This gives me the following error:
AxisFault
faultCode: {http://schemas.xmlsoap.org/soap/envelope/}Server.userException
faultSubcode:
faultString: java.net.SocketTimeoutException: Read timed out
faultActor:
faultNode:
faultDetail:
{http://xml.apache.org/axis/}stackTrace:java.net.SocketTimeoutException: Read timed out
I tried changing the TimeOut, but with no luck. Is there any basic thing that I am missing? I got no clues.
Any help will be highly appreciated.

Hi,
The sender is able to send Object successfully and part of the applet code is
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                    oos.close();
     this applet part doesnt throw any exception.But when the Servlet is about to read the object the servlet part
                       InputStream in = request.getInputStream();
               ObjectInputStream inputFromApplet = new ObjectInputStream(in);
               Object[] appletInput = (Object[]) inputFromApplet.readObject();
   this part throws the above exception.
please help me out.
Thanks
John

Post form to 3rd party website

I have searched your forums, but not found what I need.
I am new to Java, and am battling to put together code to:
a) open a URL (e.g. www.google.com)
b) post data into a form (e.g. some keywords)
c) submit the form
Where can I find an example?

Have a look at the address bar after you do a google search...
eg. "java +java3d"
http://www.google.ie/search?hl=en&q=%2Bjava+%2Bjava3d&meta=
The servlet URL is "http://www.google.ie/search"
The first parameter is after the "?" separator.
Other parameters are separated by "&".
The text is URLEncoded.
So the psuedo vague code should be something like....
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StringBuffer dynamicURL = new StringBuffer ( "http://www.google.ie/search?hl=" );
dynamicURL.append ( java.net.URLEncoder.encode ( mySearchParams ) );
dynamicURL.append ( "&meta=" ); // end of query string
URLConnection urlConn = new URLConnection ( dynamicURL );
urlConn.connect();
InputStream googleResultsStream = urlConn.getInputStream();
// now read the HTML that google returns...regards,
Owen

FileNotFoundException with multiple keywords

With multiple keywords 'pi_keyword=account and manager', my program generates: java.io.FileNotFoundException.......sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:702). But the url works fine in IE address box. In addition, if only single keyword
'pi_keyword=account ', my program works no problem. Any solution? Thanks.
The following is my program:
URL url = new URL(str);
URLConnection connection = (URLConnection) url.openConnection();
connection.setDoOutput(true);
BufferedReader in = new BufferedReader(
new InputStreamReader(connection.getInputStream()));
The fullurl is:
http://jobs.workopolis.com/jobshome/db/work.process_job?pi_post_date=&pi_smart=N&pi_sort_col=&pi_employer=Dummy&pi_advertiser=Dummy&pi_category=Dummy&pi_industry=Dummy&pi_msg=LOCATION&pi_language=EN&pi_keyword=manager and account&pi_location=British Columbia

I think whitespace isn't allowed in the keyword values, what do you get if you replace space with '+'?
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URLConnection vs sockect connection

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