Help in applet to servlet communication
Hi all,
I had posted this question earlier in the forum. I got no response though. I tried solving the example with a simple program. But it still fails. I went through the forum and did not find a concrete solution.
My problem is something like this.
I have an applet which should connect to a servlet and the servlet will connect to the db and will print output to the applet.
For this I have created an object class and I am calling it both the Servlet and Applet.
When i run the applet I see that it returns me with an error <b>"java.io.IOException: Connection failure with 500"</b>
I do not know what the error actually means and also why the connection to the servlet is failing at this point..
<b> ObjectInputStream in = new ObjectInputStream (connection.getInputStream());
</b>
I have actually deployed application to the JRun server. Is it that I have missed on something while deploying application?
Any help on this will be highly appreciated as it is pretty urgent.....
Thanks in advance....
thank u very much for the reply..
I tried doing it in another way. I have removed the object class and am directly reading the value from the table in the servlet and using the
BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
int rec = in.read();
while (rec!= -1) {
RetrieveField.append(String.valueOf((char) rec));
rec = in.read();
and then displaying the records in the TextArea.
The result seems fine.......I am able to see the records.
but I am not sure whether the object class has to be used or it is ok using BufferedReader.
Another thing is that since RetrieveField is a textarea i cannot align the results retrieved....
Regards
Similar Messages
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Applet to servlet communication
Hi all,
I am having a problem about applet servlet communication.
I am having a string array object in the applet which I want to
pass it to the servlet for further processing.
Please help me to solve this problem.It is very urgent.
If you can send me the code for that I would be very thankful to you all.
Feel free to mail me at [email protected]I guess you are stugling with the sollution of how to send an object from an applet to the
servlet:
Sollution is here:
http://forum.java.sun.com/thread.jspa?threadID=625045&messageID=3562787
Assuming that all these posts are about solving the same problem:
http://forum.java.sun.com/thread.jspa?threadID=642015&messageID=3783853#3783853
http://forum.java.sun.com/thread.jspa?threadID=642013&messageID=3783839#3783839
http://forum.java.sun.com/thread.jspa?threadID=641689&messageID=3779038#3779038
http://forum.java.sun.com/thread.jspa?threadID=641685&messageID=3779004#3779004 -
Big Problem in Applet-Servlet Communication-(Help)
I wrote an method to send serialized objects from Applet to Servlet,
the method is as following:
private ObjectInputStream postObjects (URL servlet, Serializable objs[], String sessionID) throws Exception {
ObjectInputStream in = null;
ObjectOutputStream out = null;
try{
URLConnection con = servlet.openConnection();
con.setDoInput(true);
con.setDoOutput(true);
con.setUseCaches(false);
con.setRequestProperty("Content-Type","application/x-java-serialized-object");
con.setAllowUserInteraction(false);
con.setRequestProperty("Cookie", sessionID);
out = new ObjectOutputStream(con.getOutputStream());
int numObjects = objs.length;
for(int x = 0; x < numObjects; x++){
out.writeObject(objs[x]);
out.flush();
out.close();
in = new ObjectInputStream(con.getInputStream());
}catch(Exception e){
e.printStackTrace(System.err);
throw e;
}finally{
return in;
when I call this method, I got the following error message in Applet console,
my platform is Salaris 5.8 + iPlanet 6.0.
java.io.EOFException
at java.io.ObjectInputStream$PeekInputStream.readFully(ObjectInputStream.java:2150)
at java.io.ObjectInputStream$BlockDataInputStream.readShort(ObjectInputStream.java:2619)
at java.io.ObjectInputStream.readStreamHeader(ObjectInputStream.java:726)
at java.io.ObjectInputStream.<init>(ObjectInputStream.java:251)
at com.shinewave.lms.core.client.ServletProxy.postObjects(ServletProxy.java:255)
at com.shinewave.lms.core.client.ServletProxy.doInitialize(ServletProxy.java:76)
at com.shinewave.lms.core.client.APIAdapterApplet.LMSInitialize(APIAdapterApplet.java:60)
java.lang.NullPointerException
at com.shinewave.lms.core.client.ServletProxy.doInitialize(ServletProxy.java:77)
at com.shinewave.lms.core.client.APIAdapterApplet.LMSInitialize(APIAdapterApplet.java:60)
java.lang.NullPointerException
at com.shinewave.lms.core.client.ServletProxy.doInitialize(ServletProxy.java:82)
at com.shinewave.lms.core.client.APIAdapterApplet.LMSInitialize(APIAdapterApplet.java:60)
Please help me to solve this problem, thank you very much.Hi..
Sorry abt this. But I was hoping if u could help out on this..
I am trying to implement a applet to servlet communication...
wherin the servlet would read data from the database... and send it back to the applet which gets displayed on the applet...
But the problem is that the applet is not able to establish a connection with the servlet..
I am also using another supportive class whose object is basically passed from the servlet to the applet..
could u help me..
below is the piece of code...
APPLET:
import java.net.*;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
public class TestApplet extends JApplet implements ActionListener
JButton btnLoad;
JTextField tfEmpno, tfFname, tfLname, tfSalary;
URL url;
private String webServerStr = null;
private String hostName = "sandy";
private int port = 8085;
private String servletPath = "/jdbcTest.DBDetailsServlet";
public TestApplet()
super();
// suppress Warning Message
getRootPane().putClientProperty"defeatSystemEventQueueCheck",Boolean.TRUE);
public void actionPerformed(ActionEvent ae)
if(btnLoad.getText().equals("Load"))
if(loadData())
btnLoad.setText("Save");
else
btnLoad.setText("Load");
// saveData();
public void init()
setBackground(Color.pink);
tfEmpno = new JTextField(10);
tfFname = new JTextField(10);
tfLname = new JTextField(10);
tfSalary= new JTextField(10);
JPanel panel = new JPanel();
panel.setLayout(new FlowLayout());
panel.add(tfEmpno);
panel.add(tfFname);
panel.add(tfLname);
panel.add(tfSalary);
getContentPane().add(panel, BorderLayout.CENTER);
JPanel bottom = new JPanel(new FlowLayout());
btnLoad = new JButton("Load");
btnLoad.addActionListener(this);
bottom.add(btnLoad);
getContentPane().add(bottom, BorderLayout.SOUTH);
public boolean loadData()
try
System.out.println("Web Server host name: " + hostName);
webServerStr = "http://" + hostName + ":" + port + servletPath;
System.out.println("Web String full = " + webServerStr);
String servletGET = webServerStr + "?"
+ URLEncoder.encode("UserOption") + "="
+ URLEncoder.encode("AppletDisplay");
// url = new URL(getCodeBase(),"http://sandy:8080/servlet/jdbcTest.DBDetailsServlet");
System.out.println("Complete Servlet Url => " + servletGET);
url = new URL(servletGET);
URLConnection con = url.openConnection();
con.setUseCaches(false); // Turn off caching.
InputStream in = con.getInputStream();
System.out.println("\nsuccess ....... con.getInputStream() ");
ObjectInputStream ois = new ObjectInputStream(in);
System.out.println("\nsuccess ....... new ObjectInputStream(in) ");
Object object = ois.readObject();
System.out.println("\nGot the object from servlet...");
if(object != null)
System.out.println("\nObject NOT null ...");
ArrayList result = (ArrayList) object;
jdbcTest.EmployeeValue empval = (jdbcTest.EmployeeValue) result.get(0);
tfEmpno.setText(""+empval.getEmp_no());
tfFname.setText(empval.getFname());
tfLname.setText(empval.getLname());
tfSalary.setText(""+empval.getSalary());
System.out.println("\nObject processed " + result);
repaint();
return true;
catch(Exception e)
e.printStackTrace();
System.out.println("\n\n loadData()=> E X C E P T I O N : " + e + "\n");
return false;
public void saveData()
//yet to be implemented..
SERVLEt:
package jdbcTest;
import java.util.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class DBDetailsServlet extends HttpServlet
public void doGet(HttpServletRequest req,HttpServletResponse res )throws ServletException, IOException
System.out.println("\nInside the doGet()\n");
ArrayList results = getDetails();
ObjectOutputStream oos = new ObjectOutputStream(res.getOutputStream());
oos.writeObject(results);
public void doPost(HttpServletRequest req,HttpServletResponse res )throws ServletException, IOException
System.out.println("\nInside the doPost()\n");
doGet(req,res);
public ArrayList getDetails()
try
System.out.println("\nServlet : inside GetDetails...");
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
java.sql.Connection con = java.sql.DriverManager.getConnection("jdbc:odbc:SandyDSN","","");
java.sql.Statement stmt = con.createStatement();
System.out.println("\n Statement created..");
java.sql.ResultSet rs = stmt.executeQuery("SELECT * FROM EMP WHERE EMP_NO = 222");
System.out.println("\n Query Executed...");
ArrayList results = new ArrayList();
while(rs.next())
EmployeeValue empval = new EmployeeValue();
empval.setEmp_no(rs.getLong("EMP_NO"));
empval.setFname(rs.getString("FNAME"));
empval.setLname(rs.getString("LNAME"));
empval.setSalary(rs.getLong("SALARY"));
results.add(empval);
System.out.println("\n Resultset Obtained...");
stmt.close();
con.close();
return results;
catch(Exception e)
System.out.println("Error while retreiving details....." + e);
return null;
public boolean saveDetails(EmployeeValue empval)
try
return true;
catch(Exception e)
System.out.println("Error while updating details....." + e);
return false;
The utility class EMployeeValue is as below:
package jdbcTest;
import java.io.*;
class EmployeeValue implements Serializable
private long emp_no;
private String fname;
private String lname;
private long salary;
public EmployeeValue()
super();
public EmployeeValue(long eno, String fn, String ln,long sal)
super();
setEmp_no(eno);
setFname(fn);
setLname(ln);
setSalary(sal);
public long getEmp_no()
return emp_no;
public java.lang.String getFname()
return fname;
public java.lang.String getLname()
return lname;
public long getSalary()
return salary;
public void setEmp_no(long newEmp_no)
emp_no = newEmp_no;
public void setFname(java.lang.String newFname)
fname = newFname;
public void setLname(java.lang.String newLname)
lname = newLname;
public void setSalary(long newSalary)
salary = newSalary; -
Need help with applet servlet communication .. not able to get OutputStream
i am facing problem with applet and servlet communication. i need to send few image files from my applet to the servlet to save those images in DB.
i need help with sending image data to my servlet.
below is my sample program which i am trying.
java source code which i am using in my applet ..
public class Test {
public static void main(String argv[]) {
try {
URL serverURL = new URL("http://localhost:8084/uploadApp/TestServlet");
URLConnection connection = serverURL.openConnection();
Intermediate value=new Intermediate();
value.setUserId("user123");
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setUseCaches(false);
connection.setDefaultUseCaches(false);
// Specify the content type that we will send binary data
connection.setRequestProperty ("Content-Type", "application/octet-stream");
ObjectOutputStream outputStream = new ObjectOutputStream(connection.getOutputStream());
outputStream.writeObject(value);
outputStream.flush();
outputStream.close();
} catch (MalformedURLException ex) {
System.out.println(ex.getMessage());
} catch (IOException ex) {
System.out.println(ex.getMessage());
}servlet code here ..
public class TestServlet extends HttpServlet {
* Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods.
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println(" in servlet -----------");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
ObjectInputStream inputFromApplet = null;
Intermediate aStudent = null;
BufferedReader inTest = null;
try {
// get an input stream from the applet
inputFromApplet = new ObjectInputStream(request.getInputStream());
// read the serialized object data from applet
data = (Intermediate) inputFromApplet.readObject();
System.out.println("userid in servlet -----------"+ data.getUserId());
inputFromApplet.close();
} catch (Exception e) {
e.printStackTrace();
System.err.println("WARNING! filename.path JNDI not found");
} finally {
out.close();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println(" in foGet -----------");
processRequest(request, response);
* Handles the HTTP <code>POST</code> method.
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println(" in doPost -----------");
processRequest(request, response);
* Returns a short description of the servlet.
* @return a String containing servlet description
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
}the Intermediate class ..
import java.io.Serializable;
public class Intermediate implements Serializable{
String userId;
public String getUserId() {
return userId;
public void setUserId(String userId) {
this.userId = userId;
}Hi,
well i am not able to get any value from connection.getOutputStream() and i doubt my applet is not able to hit the servlet. could you review my code and tell me if it has some bug somewhere. and more over i want to know how to send multiple file data from applet to servlet . i want some sample or example if possible.
do share if you have any experience of this sort..
Thanks. -
Applet/servlet communication for byte transmission
Hello all !
I wrote an applet to transfer binary file from web servlet (running under Tomcat 5.5) to a client (it's a signed applet) but I have a problem of interpretation of byte during transmission.
the code of the servlet is :
response.setContentType("application/octet-stream");
ServletOutputStream sos = response.getOutputStream();
FileInputStream fis = new FileInputStream(new File(
"C:\\WINDOWS\\system32\\setup.bmp"));
byte[] b = new byte[1024];
int nbRead = 1;
while (nbRead > 0) {
nbRead = fis.read(b);
System.out.println("octets lus = " + nbRead);
sos.write(b, 0, nbRead-1);
fis.close();
sos.close();et le code de l'applet qui appelle cette servlet est :
URL selicPortal = null;
try {
selicPortal = new URL(
"http://localhost:8080/AppletTest/servlet/FileManipulation");
} catch (MalformedURLException e) {
e.printStackTrace();
URLConnection selicConnection = null;
try {
selicConnection = selicPortal.openConnection();
} catch (IOException e) {
e.printStackTrace();
selicConnection.setDoInput(true);
selicConnection.setDoOutput(true);
selicConnection.setUseCaches(false);
selicConnection.setRequestProperty("Content-Type",
"application/octet-stream");
try {
InputStream in = selicConnection.getInputStream();
FileOutputStream fos = new FileOutputStream(new File(tempDir
+ "\\toto.bmp"));
byte[] b = new byte[1024];
int nbRead = in.read(b);
while (nbRead > 0) {
fos.write(b);
in.close();
fos.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}the file dowloaded is broken. it seems that bytes 01 00 or 00 01 are not correctly process.
Some ideas to help me please ?hi,
have you solved this issue.. please post me the code since i m also doing the applet/servlet communication and can use your code as reference.
how to read the content placed in the urlConnection stream in the servlet
Below is my code in applet
public void upload(byte[] imageByte)
URL uploadURL=null;
try
uploadURL=new URL("<url>");
URLConnection urlConnection=uploadURL.openConnection();
urlConnection.setDoInput(true);
urlConnection.setDoOutput(true);
urlConnection.setUseCaches(false);
urlConnection.setRequestProperty("Content-type","application/octet-stream");
urlConnection.setRequestProperty("Content-length",""+imageByte.length);
OutputStream outStream=urlConnection.getOutputStream();
outStream.write(imageByte);
outStream.close();
catch(MalformedURLException ex)
catch(IOException ex)
How can i read the byte sent on the outstream (in above code) in the servlet.
Thanks,
Mclaren -
Asynchronous applet-servlet communication
Hi all,
I am trying to implement asynchronous applet-servlet communication and need your help. Anything would help(I tried with synchronous applet-servlet communication but doesn't solve my problem).
Thanks,http://java.sun.com/docs/books/tutorial/networking/index.html
You can open a socket connection. Bother the client and the server
can have separate threads for reading and writing and that you gives you
asynchronous communication. Later, if you think the server is generating
too many threads and not scaling, you can use features of .java.nio to
make it more scalable:
java.nio.channels -
Applet/Servlet communication - StreamCorruptedException
Hi, I'm having a problem when I try to connect to a servlet. I am using applet/servlet communication. The problem only occurs when I have lauched a crystal report via http in a new window.
After the report is launched if I try to hit my servlet I get the following error:
java.io.CorruptedStreamException: invalid stream header
Not all crystal reports I launch cause this behavior but I can see nothing in the url I use to launch the report that is out of place or different than other reports.
APPLET-SERVLET CONNECTION
try {
StringBuffer path = new StringBuffer();
path.append(ip);
path.append("servlet/DatabaseServlet?");
path.append("option=getRecords&query=").append(URLEncoder.encode(query,"UTF-8"));
URL url = new URL(path.toString());
URLConnection servletConnection = url.openConnection();
servletConnection.setUseCaches(false);
servletConnection.setDoInput(true);
servletConnection.setDoOutput(true);
servletConnection.setRequestProperty("Content-Type", "application/x-java-serialized-object");
ObjectInputStream inputFromServlet = new ObjectInputStream(servletConnection.getInputStream());
rc = (RecordCollection) inputFromServlet.readObject();
inputFromServlet.close();
} catch (Exception e) {
e.printStackTrace();
SERVLET CODE
Forwards to doPost
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("session id: " + request.getSession().getId());
this.doPost(request, response);
LAUNCHING REPORT FROM APPLET
try {
String launchURL = host + directory + report + "?promptOnRefresh=0"+ "&" +
authentication + "&" + key + "&" + startPeriods + "&" + reportYears + "&" + reportTitle + "&" endPeriods "&" + locations + "&" + reportPeriod + "&" + fiscalWeek + "&" + fiscalYear + "&" +time;
context.showDocument(new URL(launchURL), "_blank");
} catch (Exception ex) {
ex.printStackTrace();
SAMPLE URL THAT CAUSES PROBLEM
http://localhost:113/Reports/OpenToBuy_3.class?promptOnRefresh=0&user0=rpuser&password0=er34sw1&[email protected]=rpuser&[email protected]=er34sw1&user0@sub2=rpuser&[email protected]=er34sw1&promptex-key="L","L1","ALL"&promptex-start="1"&promptex-years="2004","2004"&promptex-title="Report Title"&promptex-end="1"&promptex-locs="01","03","04","05"&promptex-period="Feb 2004 [04-01]"&promptex-cw="1"&promptex-cy="2004"&promptex-time=-2-52728"
Everything works fine until I launch this report then I can no longer get data from my servlet. I thought the URL lenght for the report might be the problem but I lauch a report with a URL longer than the problem one and there I don't get the errors after. When I try to connect to the servlet the println statement in the doGet method of my servlet doesn't get printed so it's not even making it inside that method in the servlet.
Anyone have any idea what could be causing this? Anyone have any ideas what would be causing this? I'm really stumped.I've seen this problem before. Because your accessing a complete URL (ie http://<host>:<port>/xxx), you are actually creating a new session. Whenever the applet opens a connection to a servlet it is running on it's own session not the same as the JSP. This is rather obvious since the Page and Applet are separate entities.
Try sending authentication with the url. I think the syntax is:
username:password@http://localhost/xxx
However I'm not sure how well this might work for Tomcat. As for Java it may try and throw a MalformedURLException I would have to test it first - it's been a long time since I used this technique!
Wish I could be more help,
Anthony -
Applet Servlet communication (urgent)
Hi,
I m using Netscape Enterrpise server 4.0 as my web server. I am passing data from applet to servlet using BufferedInputStream(). But it takes about 30 seconds to send the data. If i don't use it, the data is not being read by the servlet. Is there any alternative to this ? Please help.
ThanksIt's only the primary key field that i am passing to the servlet from applet .. For this particular process, it takes 30 seconds + other things like loading the applet, etc. so in all, it takes about 1 minute just to fetch the data from servlet which is not reasonable. We have monitored the whole process. We found that other things like query, etc. does not take much time, but BufferedInputStream() itself takes 30 seconds. Regarding communication line, it is quite fast. We are a corporate sector, so no doubt about the speed of the communication line ...
Thanks for help. -
Sending a file from Applet to servlet HELP me Please
Sorry, i have the problem this is my code Applet & Servlet but it seems working asynchronously if you have some ideas please reply me i send bytes on outputstream but the inputstream of servlet receive nothing bytes but write my system.out.print on screen server:
Applet:
URL servletURL = new URL(codebase, "/InviaFile/servlet/Ricevi");
HttpURLConnection urlConnection = (HttpURLConnection) servletURL.openConnection();
urlConnection.setRequestMethod("POST");
urlConnection.setUseCaches(false);
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.setAllowUserInteraction(false);
urlConnection.setRequestProperty("Content-Type", "application/octet-stream");
urlConnection.setRequestProperty("Content-length", String.valueOf(100));
urlConnection.connect();
if(urlConnection.HTTP_BAD_REQUEST == HttpURLConnection.HTTP_BAD_REQUEST){
/*System.out.println("Cattiva Richiesta: "+urlConnection.getContentEncoding());
System.out.println("Tipo di metodo: "+urlConnection.getRequestMethod());
System.out.println("Tipo di Risposta: "+urlConnection.getResponseCode());
System.out.println("Tipo di messaggio: "+urlConnection.getResponseMessage());
System.out.println("Tipo di contenuto: "+urlConnection.getContentType());
System.out.println("Tipo di lunghezza contenuto: "+urlConnection.getContentLength());
System.out.println("Tipo di doinput: "+urlConnection.getDoInput());
System.out.println("Tipo di doouput: "+urlConnection.getDoOutput());
System.out.println("Tipo di URL: "+urlConnection.getURL());
System.out.println("Tipo di propriet� richiesta: "+urlConnection.getRequestProperty("Content-Type"));
System.out.println("Entra if");
DataOutputStream dout = new DataOutputStream(urlConnection.getOutputStream());
InputStream is = urlConnection.getInputStream();
if(ritornaFile("C:/Ms.tif", dout))System.out.println("Finita lettura");
dout.close();
urlConnection.disconnect();
System.out.println("Fine Applet");
}catch(Exception e) { System.err.println(e.getMessage());e.printStackTrace();}
public boolean ritornaFile(String file, OutputStream ots)throws Exception{
FileInputStream f = null;
try{
f = new FileInputStream(file);
byte[] buf = new byte[4 * 1024];
int byteLetti;
while((byteLetti = f.read()) != -1){ots.writeByte(buf, 0, byteLetti);ots.flush();
while((byteLetti = f.read()) != -1){ots.write(byteLetti);ots.flush();
System.out.println("byteLetti= "+byteLetti);
return true;
}catch(Exception ex){
System.err.println(ex.getMessage());
return false;
}finally{
if(f != null)f.close();
Servlet:
HttpSession ses = request.getSession(true);
System.out.println("Passa servlet "+request.getMethod());
System.out.println("Passa servlet "+ses.getId());
ServletInputStream servletinputstream = request.getInputStream();
DataInputStream dis = new DataInputStream(request.getInputStream());
int c = dis.available();
System.out.println("c="+c);
//ServletOutputStream servletoutputstream
//response.getOutputStream();
response.setContentType("application/octet-stream");
System.out.println("URI= "+request.getRequestURI());
System.out.println("pathTranslated: "+request.getPathTranslated());
System.out.println("RemoteUser: "+request.getRemoteUser());
System.out.println("UserInRole: "+String.valueOf(request.isUserInRole("")));
System.out.println("pathInfo: "+request.getPathInfo());
System.out.println("Protocollo: "+request.getProtocol());
System.out.println("RemoteAddr:"+request.getRemoteAddr());
System.out.println("RemoteHost:"+request.getRemoteHost());
System.out.println("SessionID:"+request.getRequestedSessionId());
System.out.println("Schema:"+request.getScheme());
System.out.println("SeesionValido:"+String.valueOf(request.isRequestedSessionIdValid()));
System.out.println("FromURL:"+String.valueOf(request.isRequestedSessionIdFromURL()));
int i = request.getContentLength();
System.out.println("i: "+i);
ritornaFile(servletinputstream, "C:"+File.separator+"Pluto.tif");
System.out.println("GetMimeType= "+getServletContext().getMimeType("Ms.tif"));
InputStream is = request.getInputStream();
int in = is.available();
System.out.println("Legge dallo stream in="+in);
DataInputStream diss = new DataInputStream(servletinputstream);
int ins = diss.read();
System.out.println("Legge dallo stream ins="+ins);
int disins = diss.available();
System.out.println("Legge dallo stream disins="+disins);
is.close();
System.out.println("Fine Servlet");
catch(Exception exception) {
System.out.println("IOException occured in the Server: " + exception.getMessage());exception.printStackTrace();
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
processRequest(request, response);
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, java.io.IOException {
processRequest(request, response);
/** Returns a short description of the servlet.
public String getServletInfo() {
return "Short description";
public void ritornaFile(InputStream its, String fileDest )throws Exception{
FileOutputStream f = null;
try{
f = new FileOutputStream(fileDest);
byte[] buf = new byte[2 * 1024];
int byteLetti;
while((byteLetti = its.read()) != -1){
f.write(buf, 0, byteLetti);
f.flush();
System.out.println("Byteletti="+byteLetti);
}catch(Exception ex){
System.err.println(ex.getMessage());
}finally{
if(f != null)f.close();Hi all,
Can anyone help me.I am trying to send an audio file from a applet to servlet with HTTP method(no raw sockets), also the servlet shld be able to save the file on the server.Any suggestions welcome.USing audiostream class from javax.sound.sampled.
The part of applet code which calls servlet is :
URL url = new URL("http://" + host + "/" + context + "/servlet/UserUpdateWorkLogAudio?userid=" + userId.replace(' ', '+') + "&FileName=" + filename.replace(' ', '+'));
URLConnection myConnection = url.openConnection();
myConnection.setUseCaches(false);
myConnection.setDoOutput(true);
urlConnection.setRequestProperty("Content-Type", "application/octet-stream");
myConnection.connect();
out = new BufferedOutputStream(myConnection.getOutputStream());
AudioSystem.write(audioInputStream, fileType,out); // IS THIS RIGHT APPROACH?
************************end of applet code**********************
************************servlet code******************************
try
{BufferedInputStream in = new BufferedInputStream(request.getInputStream());
????????What code shld i write here to get the audio file stream
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(filename));
*********************************************end***********************
Thanks
Joe. -
Applet Servlet communication compiles but does not communicate
Hi,
I have a applet which has a button named A. By clicking the button, the applet passes the letter A to the servlet. The servlet in turn accesses an Oracle database and retrieves the name corresponding to letter A from a table (name is Andy in the present case). The servlet interacts with the databse via a simple stored procedure and uses its output parameter to display the name Andy back in the applet.
Both the applet and servlet codes have compiled fine(servlet code compiled with -classpath option to servlet jar using a TOMCAT). However, on clicking button A in the applet, I do not get the name Andy.
Any help/suggestion in resolution of this is highly appreciated. Thanks in advance.
HTML CODE:
<html>
<center>
<applet code = "NameApplet.class" width = "600" height = "400">
</applet>
</center>
</html>
STORED PROCEDURE CODE:
procedure get_letter_description(
ac_letter IN CHAR,
as_letter_description OUT VARCHAR2) IS
BEGIN
SELECT letter_description INTO as_letter_description FROM letter WHERE letter =
ac_letter;
EXCEPTION
WHEN no_data_found THEN as_letter_description := 'No description available';
END get_letter_description;
APPLET CODE:
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.util.*;
import java.io.*;
import java.net.*;
public class NameApplet extends Applet implements ActionListener
private TextField text;
private Button button1;
private String webServerStr = null;
private String hostName = "localhost";
private int port = 8080;
private String servletPath = "/examples/servlet/NameServlet?letter=";
private String letter;
public void init()
button1 = new Button("A");
button1.addActionListener(this);
add(button1);
text = new TextField(20);
add(text);
// get the host name and port of the applet's web server
URL hostURL = getCodeBase();
hostName = hostURL.getHost();
port = hostURL.getPort();
webServerStr = "http://" + hostName + ":" + port + servletPath;
public void actionPerformed(ActionEvent e)
if (e.getSource() == button1)
letter = "" + 'A';
private String getName(String letter){
String name = "" ;
try {
URL u = new URL(webServerStr + letter);
Object content = u.getContent();
name = content.toString();
} catch (Exception e) {
System.err.println("Error in getting name");
return name;
SERVLET CODE:
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.sql.*;
import java.util.Properties;
public class NameAppletServlet extends HttpServlet {
private static Connection conn = null;
private static final char DEFAULT_CHAR = 'A';
private static final char MIN_CHAR = 'A';
private static final char MAX_CHAR = 'G';
private static final String PROCEDURE_CALL
= "{call get_letter_description(?, ?)}";
protected void doGet( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
handleHttpRequest(request, response);
protected void doPost( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
handleHttpRequest(request, response);
protected void handleHttpRequest( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
String phrase = null;
char letter = getLetter(request, DEFAULT_CHAR);
if (letter >= MIN_CHAR && letter <= MAX_CHAR) {
try {
name = getName(conn, letter);
} catch (SQLException se) {
String msg = "Unable to retrieve name from database.";
name = msg;
} else {
String msg = "Invalid letter '" + letter + "' requested.";
//throw new ServletException(msg);
phrase = msg;
response.setContentType("text/plain");
PrintWriter out = response.getWriter();
out.println(name);
private String getName(Connection conn, char letter)
throws SQLException
CallableStatement cstmt = conn.prepareCall(PROCEDURE_CALL);
cstmt.setString(1, String.valueOf(letter));
cstmt.registerOutParameter(2, Types.VARCHAR);
cstmt.execute();
String name = cstmt.getString(2);
cstmt.close();
return name;
private char getLetter(HttpServletRequest request, char defaultLetter) {
char letter = defaultLetter;
String letterString = request.getParameter("letter");
if (letterString!=null) {
letter = letterString.charAt(0);
return letter;
public void init(ServletConfig conf) throws ServletException {
super.init(conf);
String dbPropertyFile = getInitParameter("db.property.file");
try {
Class.forName("oracle.jdbc.driver.OracleDriver");
conn = DriverManager.getConnection(
"jdbc:oracle:thin:myserver:1521:CDD",
"scott",
"tiger");
} catch (IOException ioe) {
throw new ServletException(
"Unable to init ReinforcementServlet: " + ioe.toString());
} catch (ClassNotFoundException cnfe) {
throw new ServletException(
"Unable to init ReinforcementServlet. Could not find driver: "
+ cnfe.toString());
} catch (SQLException se) {
throw new ServletException(
"Unable to init ReinforcementServlet. Error establishing"
+ " database connection: " + se.toString());
}Hi,
I am not able to understand by which method you are doing Applet-Servlet commuincation.
If you want to use Object Serialization method, plz.get the details from following URL.
http://www.j-nine.com/pubs/applet2servlet/
Ajay -
Is there a good advanced review on applet-servlet communication
I am working on a web application and unfortunately experiencing a lot of trouble trying to use an applet as front end which interacts with a couple of servlets running on Tomcat. I need to get data from one servlet and send data to another.
There is a lot of messages posted in this and other forums about how to do this, but none of them got a response pointing to a useful advanced reference on this subject. I have reviewed some of the references given, but couldn't find a thorough detailed advanced reference on applet-servlet communication. For this I mean an exhaustive explanation of the mechanism of communication and when and when is neccesary to use each of the multiple configuration possibilities regarding content-type, message-length, request-method, connection settings, and so on.
Would anybody be so kind to show me the right direction? As I read the (literally) hundreds of messages posted on this topic, I see this info as widely useful. Most of the topic tracks ends on void or with painful no-way sentences, and maybe many people is avoiding Java technology on web application because of this problem (development delays can abort a project).This sample chapter in Java developers' guide to Servlets and Jsp focuses on Applet-Servlet communication, is a pretty good one, and is free :
http://www.javaranch.com/bunkhouse/samps/2809ch12.pdf
As to an exhaustive & complete guide that covers absolutely everything, I may be wrong but I doubt you'll find anything like that...unless there is a book somewhere dedicated to the subject. -
Applet-servlet communication, object serialization, problem
hi,
I encountered a problem with tomcat 5.5. Grazing the whole web i didn't find any solution (some guys are having the same problem but they also got no useful hint up to now). The problem is as follows:
I try to build an applet-servlet communication using serialized objects. In my test scenario i write a serialized standard java object (e.g. a String object) onto the ObjectOutputStream of the applet/test-application (it doesn't matters wheter to use the first or the latter one for test cases) and the doPost method of the servlet reads the object from the ObjectInputStream. That works fine. But if i use customized objects (which should also work fine) the same code produces an classnotfound exception. When i try to read and cast the object:
TestMessage e = (TestMessage)objin.readObject();
java.lang.ClassNotFoundException: TestMessage
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1359)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1205)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
...That seems strange to me, because if i instantiate an object of the same customized class (TestMessage) in the servlet code, the webappclassloader doesn't have any problems loading and handling the class and the code works fine!
The class is located in the web-inf/classes directory of the application. I've already tried to put the class (with and without the package structure) into the common/classes and server/classes directory, but the exception stays the same (I've also tried to build a jar and put it in the appropriate lib directories).
I've also tried to catch a Throwable object in order to get information on the cause. But i get a "null" value (the docu says, that this will may be caused by an unknown error).
I've also inspected the log files intensively. But they gave me no hint. Until now I've spend a lot of time on searching and messing around but i always get this classnotfound exception.
I hope this is the right place to post this problem and i hope that there is anyone out there who can give me some hint on solving this problem.
Kindly regards,
Danielhi, thanks for the reply,
all my classes are in the web-inf/classes of the web-app and have an appropriate package structure. thus the TestMessage class is inside a package.
i tried some names for the testclass but it didn't matter. the exception stays the same. I also tried to put the jar in the common/lib but the problem stays.
Well the problem with loaded classes: As i mentioned in the post above i can instantiate an object of TestMessage in the code without any problems (so the classloader of my webapp should know the class!!)
only when reading from the objectinputstream the classloader doesn't seem to know the class?? maybe theres a parent classloader resposible for that and doesn't know the class?
strange behaviour...
p.s. sending the same object from the servlet to the client works well
regards
daniel
Message was edited by:
theazazel -
Applet-Servlet communication (Serialization)
I need to pass certain objects from server side to the client applet. My applet is embedded in the jsp. Just before calling the applet, Im able to pass the string parameters via jsp <param>tag. Now I need to pass an object which is of a class type. I resorted to serialization. When i try to serialize the object in jsp and try to deserialize it in the applet I get this exception "java.io.StreamCorruptedException: invalid stream header".The jdk versions of applet and servlet are the same. Classes are serializable. But yet am not able to find out the reason for this annoying exception. Please help!
Thanks for your reply.
Iam calling the writeObject on an object, writing it to ObjectOutputStream and Iam using ObjectInputStream at the applet side to readObject which is serialized! Iam making use of HttpURLConnection only. Let me cut & paste a part of my applet & JSP code here.
APPLET:
=======
HttpURLConnection jspConnection = null;
String urlString = ServerAdd+"/xyz/abc.jsp";
try{
URL url = new URL(urlString);
jspConnection = (HttpURLConnection)url.openConnection();
}catch(Exception e){
e.printStackTrace();
jspConnection.setDoInput(true);
jspConnection.setDoOutput(true);
jspConnection.setUseCaches(false);
jspConnection.setDefaultUseCaches(false);
jspConnection.setUseCaches(false);
jspConnection.setDefaultUseCaches(false);
jspConnection.setRequestProperty("Content-Type", "application/octet-stream");
try{
System.out.println("Getting inputstream from servlet...");
ObjectInputStream inputFromServlet = new ObjectInputStream(jspConnection.getInputStream());
System.out.println("Getting bpiPackage from servlet...");
bpiPackage = (BPIPackage)inputFromServlet.readObject();
inputFromServlet.close();
jspConnection.getInputStream().close();
jspConnection.disconnect();
jspConnection = null;
System.out.println("Data transmission from servlet complete...");
}catch(MalformedURLException e){
System.out.println(e);
}catch(IOException e){
System.out.println(e);
}catch(ClassNotFoundException e){
System.out.println(e);
StreamCorruptedException is thrown here
ObjectInputStream inputFromServlet = new ObjectInputStream(jspConnection.getInputStream());
JSP side:
========
BPIPackage pkg = (BPIPackage)session.getAttribute("pkg");
try{
System.out.println("Sending package object to applet...");
ObjectOutputStream outputToApplet = new ObjectOutputStream(response.getOutputStream());
System.out.println("Writing package object...");
outputToApplet.writeObject(pkg);
outputToApplet.flush();
outputToApplet.close();
System.out.println("Data transmission to applet complete...");
}catch (IOException e){
e.printStackTrace();
This exception occurs only when applet tries to deserialize data passed from JSP. There is no problem in the connection because there is no exception thrown when the reverse happens (ie.serializing in the applet and deserializing in the JSP using the same jspConnection)
I hope the code makes my problem clear to you.
In your reply I did not get this:
"writing it to a ByteArrrayOutputStream, and taking those bytes, and base64 encoding them, sticking the value in an applet param.
Then the applet is getting the applet param, and building a ByteArrayInputStream from it, and calling readObject on it.Could you elaborate more? -
Https applet servlet communication
Hi friends, is there any way to make a communication between applet and servlet via https?
URLConnection works fine.
Now for the fine print...
If you have an applet running in MSJVM (equivalent to 1.1.X), Netscape JVM (1.1.x) or Sun Java Plugin (until v. 1.3.X), URLConnection simply uses the browser's SSL implementation and SSL works fine if the browser is correctly configured. The trusted CA certificates are the CA certificates in the Internet Explorer trusted CA database (if running in Internet Explorer) or the Netscape trusted CA database (if running in Netscape).
If your applet runs under Sun Java Plugin 1.4.X (required by Mozilla and Netscape 7, and probably by Internet Explorer running under Windows XP and 2003 - not for technical reasons but by legal ones), the story is different.
URLConnection uses JSSE (Sun's pure Java SSL implementation), and it uses the Sun Plugin trusted CA database (the file cacerts). The list of CAs is smaller than the list of Internet Explorer or Netscape, and it is not easy to update (requires a manual process). Adding to it, older versions (1.4.0, 1.4.1 and 1.4.2 until 1.4.2_02) simply have problems if you are using a Microsoft proxy that requires NTLM authentication.
So if you want to use SSL you need to be aware of all that deployment problems.
a) Use the latest version of the Sun Plug-In you can deploy in your clients (1.4.2_04)
b) Verify if the web server running HTTPS has a certificate issued by some CA included in the CACERTS list (if you have very few clients, you can try to update CACERTS manually for each client if your CA is not included in the CACERTS file, but probably it is cheaper to get a certificate issued by some CA included in the CACERTS instead.) -
EOF exception during applet - servlet communication
I am developing a system for the US Gov't. This system currently
utilizes several applets which access corresponding servlets on
WebLogic. Seemingly, things went wrong for no apparent reason this
morning. When, trying to run our applets, WebLogic throws an exception:
"Caught EOFException in the stream header" These exceptions occur
everytime the servlet would open the input stream from the applet. What
makes things mind-boggling is that these applets/servlets were working
this morning, and suddenly now give these exceptions. The code for both
the applets and servlets has not been touched in weeks. Furthermore, i
tested even further by running WebLogic locally and running the applets
in our IDE (as applications) and the same results occur. I am running
WebLogic 5.1 SP6 on both the remote and local system and am utilizing
JDK 1.3 on both as well. The server is running on WinNT SP6 and locally
is Win2000 Pro SP1. These applets are critical to the entire system and
i am just totally baffled as to why something that was working fine one
day ago should all of the sudden spit up errors and exceptions.
If anyone can give me some insight as to what is going on, please let me
know.
Thank you,
Randy Strobel
[email protected]
Randy,
I don't know of any particular reasons why WebLogic would suddenly affect an
application in the manner that you describe. Start by figuring out where
the message comes from:
> "Caught EOFException in the stream header"
I assume that is in WebLogic's code, not yours? Figure out as close as
possible who is detecting this error condition. If it is in WebLogic's
code, you can ask support at BEA to tell you what it is complaining about
(i.e. what it is expecting to read).
You will have to post the exception trace here and it would help to see the
code that is causing the exception.
Cameron Purdy
Tangosol, Inc.
http://www.tangosol.com
+1.617.623.5782
WebLogic Consulting Available
"Randy Strobel" <[email protected]> wrote in message
news:[email protected]...
> I am developing a system for the US Gov't. This system currently
> utilizes several applets which access corresponding servlets on
> WebLogic. Seemingly, things went wrong for no apparent reason this
> morning. When, trying to run our applets, WebLogic throws an exception:
> "Caught EOFException in the stream header" These exceptions occur
> everytime the servlet would open the input stream from the applet. What
> makes things mind-boggling is that these applets/servlets were working
> this morning, and suddenly now give these exceptions. The code for both
> the applets and servlets has not been touched in weeks. Furthermore, i
> tested even further by running WebLogic locally and running the applets
> in our IDE (as applications) and the same results occur. I am running
> WebLogic 5.1 SP6 on both the remote and local system and am utilizing
> JDK 1.3 on both as well. The server is running on WinNT SP6 and locally
> is Win2000 Pro SP1. These applets are critical to the entire system and
> i am just totally baffled as to why something that was working fine one
> day ago should all of the sudden spit up errors and exceptions.
>
> If anyone can give me some insight as to what is going on, please let me
> know.
> Thank you,
> Randy Strobel
> [email protected]
>
>
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