applet servlet communication with httpconnection.
hi
I have to connect applet to the servlet through http connection i am using httpurlconnection.
Problem is that i want to save time in connecting applet to servlet on every click of button i created the function to connect to servlet but i can't call this function in init() method i have to call this function every times i need to connect to servlet.So if anyone has idea how can i connect to servlet on time only and use the same url again and again.
here is the code.
private void createConnection() {
try {
ServletURL = new URL("http://localhost:8582/servlet/servlets.DispatcherRequest");
//ServletURL= new URL(getCodeBase(),"/servlet/servlets.DispatcherRequest");
ServletConnection = (HttpURLConnection) ServletURL.openConnection();
//set connection for input and out mode and set no cache for updated results.
ServletConnection.setDoOutput(true);
ServletConnection.setDoInput(true);
ServletConnection.setRequestProperty("Connection", "Keep-Alive");
ServletConnection.setUseCaches(false);
ServletConnection.connect();
} catch (Exception e) {
jTextAreaMsg.setText(e.getMessage());
}
}
so i have to call this function everytime i need to use servlet. and perform following task.
doProcessing(){
try {
//output stream to write the data
OutputStreamWriter outWrite = getHttpOutputStream();
String sTemp = new StringBuilder().append("{ProcessCode}").append(sBarCode).append("<").toString();
outWrite.write(sTemp);
outWrite.flush();
outWrite.close();
//input data stream
InputStream in = getHttpInputStream();
int chr;
while ((chr = in.read()) != -1) {
sBuff.append((char) chr);
}
in.close();
} catch (Exception e) { jTextAreaMsg.append(e.toString()); }
}
Is there any way that i can use createconnection() function as global object and use it when i need.
If i use createConnection() and then immidiatly doProcessing() function then it works but if i store createconnection() in init() block it work first time but on next click of button it gives error "java.net.ProtocolException: Cannot write output after reading input."
Please help me guys
[2292 byte] By [
amitwaliaa] at [2007-10-2 5:53:39]
i am doing the same thing. but i m not able to invoke Servlet method.
Plz help..
Applet Code
URL cBase=getCodeBase();
String codeBase = cBase.toString();
int iSlash= codeBase.lastIndexOf("/");
codeBase= codeBase.substring(0,iSlash);
iSlash= codeBase.lastIndexOf("/");
codeBase= codeBase.substring(0,iSlash);
System.out.println("codebase= " + codeBase);
String location = codeBase + "/AttrEditorServlet";
URL url = new URL(location);
//URL url = new URL(cBase, "AttrEditorServlet");
//URL url = new URL("http","10.192.10.231",8080,"/attrEditorServlet/AttrEditorServlet");
HttpURLConnection con = (HttpURLConnection )url.openConnection();
con.setRequestProperty("Connection", "Keep-Alive");
con.setDoOutput(true);
con.setDoInput(true);
con.setUseCaches(false);
System.out.println("val of bad request = " + con.HTTP_BAD_REQUEST);
System.out.println("http url val bad request = " + HttpURLConnection.HTTP_BAD_REQUEST);
//con.connect();
System.out.println("get URL = " + con.getURL());
if(con.HTTP_BAD_REQUEST == HttpURLConnection.HTTP_BAD_REQUEST)
{
System.out.println("bad request");
}
System.out.println("URL = " + con.getURL());
OutputStreamWriter out = new OutputStreamWriter(con.getOutputStream());
out.write(connectionStr);
out.flush();
Server Code
protected void doPost (HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
ObjectOutputStream outputToApplet = null;
ObjectInputStream inputFromApplet = null;
Date DateToday = null;
try
{
System.out.println("inside dopost method");
//Servlet recieve connection string as an input from applet
//e.g. = "jdbc:oracle:thin:tifeur_ws_and/tifeur@10.192.252.27:1521:bacosdb"
/// and then return an image to applet.
inputFromApplet = new ObjectInputStream(request.getInputStream());
System.out.println("Read Connection String from Applet : " + inputFromApplet.readObject());
outputToApplet = new ObjectOutputStream(response.getOutputStream());
//String str = new String("- this message is from servlet-");
/**
* send awt.image object from servet to Applet
*/
outputToApplet.writeObject("Send Image to applet");
outputToApplet.flush();
outputToApplet.close();
inputFromApplet.close();
}
catch( Exception e)
{
e. printStackTrace();
}
}
to invoke a servlet u must set the web.xml file or u hav eto use servlet invoker.
use servlet mapping that is more secure.
what is ur context name and servlet name
what is this
attrEditorServlet/AttrEditorServlet
is attrEditorServlet ur context or folder or package..........?
did u do that...........?
thnks foy ur reply..
my web.xml is.
<web-app>
<description>Embedded OC4J</description>
<taglib>
<taglib-uri>http://xmlns.oracle.com/j2ee/jsp/tld/spatial/mvtaglib.tld</taglib-uri>
<taglib-location>/WEB-INF/mvtaglib.tld</taglib-location>
</taglib>
<servlet>
<servlet-name>AttrEditorServlet</servlet-name>
<servlet-class>mypackage.servlet.AttrEditorServlet</servlet-class>
<!--<load-on-startup>1</load-on-startup>-->
</servlet>
<servlet-mapping>
<servlet-name>AttrEditorServlet</servlet-name>
<url-pattern>/AttrEditorServlet/*</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>jsp/webmap.jsp</welcome-file>
</welcome-file-list>
</web-app>
URL is = " http://10.192.10.231:8080/AttributeEditor/AttrEditorServlet"
if i run this url from addrress bar of Browser it invokes first init() method and doGet() method()
so i think there is no problem with url. something is wrong in code. or should it depends on web server (tomcat)setting.
Hey Amit,
I am not sure if I have understood your requirement correctly.
But on preliminary analysis I think this would help:
Make a different class and have your createConnection() in it.
Make an object of this class in your applets init() and initialize it.
Rohan
ok if thr is no problem in calling the servlet then i can see only one possibility you are calling do post method and in my knowledge applet cannot call do post method directly , applet calls service method only so if you copy ur code in service method then it should work another thing in ur web.xml file if u change ,just give it a try, servlet mapping tag from "/AttrEditorServlet/*" to "/AttrEditorServlet" only it should definatly work .give it a go.
