Writing byte array to JspWriter

Hi,
I'm pretty new to JSPs / Servlets and I have what may be a silly question. In side of a JSP scriptlet, I call an external library which returns me a byte[] containing a sequence characters in a single byte encoding (utf-8, I think). Essentially, I want to write this single byte text to the implicit out object, but that doesn't work as the underlying Writer (as I understand things) is expecting utf16.
Here's some psuedocode showing what I'd like to do, but can't quite:
<%
byte[] myBytes = myModule.methodReturnsUTF8Bytes( );
out.write(myBytes);
%>
So, what can I do? Thanks in advance.
-ts1971

ts1971 wrote:
<%
byte[] myBytes = myModule.methodReturnsUTF8Bytes( );
String myString = new String(myBytes, "UTF-8");
out.write(myString);
%>Just set the response encoding. More about characters and bytes in Java/JSP/Servlet: [http://balusc.blogspot.com/2009/05/unicode-how-to-get-characters-right.html].
Oh, take care with memory usage. The above code is memory hogging.

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try
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In the following code, I use a ASN1SDSSSignature class, which is a subclass that I created from the Siganture class, to create and verify an SDSS signature. The ASN1SDSSSignature has two ASN1Integer class variables:
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ASN1 type mismatch!
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Hi,
I have a question which I would really appreciate any help on.
I am trying to send a byte array, that contains multiple types using a UDP app. and then receive it on the other end.
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However on the receiving side, I am not sure how to be able to correctly retrieve the 4 types. Before I was explicitely creating those objects for sending, then I was casting them again on the receiving side to retrieve then and it does work.
But if I create a O_struct object and cast it as I did before with the indiv objects on the receiving end, I can't get the correct retrievals.
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If there an easier way to do I certainly will appreciate that advise as well.
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public class O_struct implements Serializable {
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O_struct struct = ...;
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I am worried that having to create new objs every time it is sending a byte array will affect my application.
That's the wrong way to approach this. You're talking about adding complexity to your code and fuglifying it because you think it might improve performance. But you don't know if it will, or by how much, or even if it needs to be improved.
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That's an idea!
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baftos - thank you for your advice, i will try that and see how it goes.
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hi
iam trying to implement socket programming over UDP. Iam writing for the server side now.I need to send an image file from server to a client via a gateway so basically ive to do hand-shaking with the gateway first and then ive to send image data in a sequence of small messages with a payload of 1 KB.The data message should also include a header of 16 bit sequential number and a bit to indicate end of file.
Iam able to complete registration process(Iam not sure yet).I dnt know how to include sequential number and a bit to indicate end of file.
I would like to have your valuable ideas about how to proceed further
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HI Rolf.k.
Thank you for the small program it was helpfull.
You got right about that proberly there will be conflict with some spurios data, I can already detect that when writing the data to a spreadsheet file.
I writes the data in such a way, that in each line there will be a date, a timestamp, a tab and a timestamp at the end. That means two columns.
When i set given samplerate up, that controls the rate of the data outflow from the device, (1,56 Hz - 200 Hz),   the data file that i write to , looks unorderet.
i get more than one timestamp and severel datavalues in every line and so on down the spreadsheet file.
Now the question is: Could it be that the function that writes the data to the file, can't handle the speed of the dataflow in such a way that the time stamp cant follow with the data flowspeed. so i'm trying to set the timestamp to be with fractions of the seconds by adding the unit (<digit>) in the timestamp icon but its not working. Meaby when i take the fractions off a second within the timestamp i can get every timestamp with its right data value. Am i in deeb water or what do You mean!??
AAttached Pics part of program and a logfile over data written to file
regards
Zamzam
HFZ
Attachments:
DataFlowWR.JPG ‏159 KB
Datalogfile.JPG ‏386 KB

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[email protected]

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               response.getOutputStream().flush();
But this also throws a error in the server :
java.lang.IllegalStateException: getOutputStream() has already been called for this response
     at org.apache.catalina.connector.Response.getWriter(Response.java:606)
     at org.apache.catalina.connector.ResponseFacade.getWriter(ResponseFacade.java:195)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.processTemplate(FreeMarkerView.java:344)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.doRender(FreeMarkerView.java:280)
     at org.springframework.web.servlet.view.freemarker.FreeMarkerView.renderMergedTemplateModel(FreeMarkerView.java:225)
     at org.springframework.web.servlet.view.AbstractTemplateView.renderMergedOutputModel(AbstractTemplateView.java:174)
     at org.springframework.web.servlet.view.AbstractView.render(AbstractView.java:239)
     at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1142)
     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:879)
     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:792)
     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:476)
     at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:441)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
     at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:672)
     at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:463)
     at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:398)
     at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:301)
     at org.ca.ielts.presentationtier.servlet.AuthorisationAuthenticationFilter.doFilter(Unknown Source)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
     at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:868)
     at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:663)
     at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
     at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
     at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
     at java.lang.Thread.run(Thread.java:595)
Any Clues how this has to be fixed.????

Byte Array Copy

Hello,
I have a problem that I have to write code to address the issue of modem disconnections while copying data. The problem is that I have to programmactially dial modems and copy programs to a remote windows based system. The issue is that I sometimes get disconnected from the remote site and loose my copy progress. I want to be able to be able to break apart an executable into chunks and copy those chunks to the remote harddrive and if I get disconnect, I will re dial the connection and pick up where I left off so that I dont loose the time that I spent already copying the file.
I am currently using this method for copying the executables across the dial up connection but need to modify it and to be honest I dont know how. I know I should stuff the executable into some sort of byte array, get the length of that array, and copy each byte array element to the harddrive; loop through the array until the copy is complete. If disconnection or "semaphore timeout" exception is thrown, redial the connection, read the bytes that are already written on the remote locations harddrive, compare the bytes to what is stored locally, and copy those bytes until complete.
Here is the method that I am using. I understand that I could use NIO to do the copy and it would be faster but I dont want to have to make major changes. I have attempted to search google for answers but only can find methods like this. Which is basically what I have...
    public static boolean uploadPackage(String src,String dst) {
        try {
            InputStream in = new FileInputStream(src);
            OutputStream out = new FileOutputStream(dst);
            // Transfer bytes from in to out
            byte[] buf = new byte[1024];
            int len;
            while ((len = in.read(buf)) > 0) {
                System.out.println("WRITING BUFFER " + len + " " + in.read(buf));
                out.write(buf, 0, len);
            in.close();
            out.close();
            return true;
        } catch (IOException e) {
            System.out.println("IOEXCEPTION " + e);
            return false;
    }

Dukes are worthless.
Do you have a question? I didn't see one.
Why do you feel the need to put a bunch of byte arrays to disk? The file itself is ultimately a byte array. Why not just store a file that says what the last byte successfully transferred was. Probably it should also indicate the last file modification date, so you can see if the file has changed out from under you between transfers. Then you can just reload the file and resend the bits you need.
For that matter, there must be a system that can transfer files in bits. I used to do this with uuencode and split on shell script. I wouldn't be surprised if rsync or something like it has support for something like this.

Reading in any file and converting to a byte array

Okay what I am trying to do is to write a program that will read in any file and convert it into a int array so that I can then manipulate the values of the int array and then re-write the file. Once I get the file into an int array I want to try and compress the data with my own algorithm as well as try to write my own encryption algorithm.
What I have been looking for is code samples that essentially read in the file as a byte array and then I have been trying to convert that byte array into an int array which I could then manipulate. So does anyone have any sample code that essentially takes a file and converts it into an int array and then converts it back into a byte array and write the file. I have found code that is close but I guess I am just too new to this. Any help would be appreciated.

You can read a whole file into a byte array like this:File f = new File("somefile");
int size = (int) f.length();
byte[] contents = new byte[size];
DataInputStream in = new DataInputStream(
new BufferedInputStream(new FileInputStream(f)));
in.readFully(contents);
in.close();Note that you need to add in the proper exception handling code. You could also use RandomAccessFile instead of the DataInputStream.
Writing a byte array to a file is easier; just construct the FileOutputStream, call write on it with the byte array, and close the stream.

Writing byte array to JspWriter

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