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  • Better to build or buy a compute grid platform?

    - by James B
    I am looking to do some quite processor-intensive brute force processing for string matching. I have run my prototype in a multi-threaded environment and compared the performance to an implementation using Gridgain with a couple of nodes (also multithreaded). The performance I observed was that my Gridgain implementation performed slower to my multithreaded implementation. It could be the case that there was a flaw in my gridgain implementation, but it was only a prototype, and I thought the results were indicative. So my question is this: What are the advantages of having to learn and then build an implementation for a particular grid platform (hadoop, gridgain, or EC2 if going hosted - other suggestions welcome), when one could fairly easily put together a lightweight compute grid platform with a much shallower learning curve?...i.e. what do we get for free with these cloud/grid platforms that are worth having/tricky to implement? (Please note, I don't have any need for a data grid) Cheers, -James (p.s. Happy to make this community wiki if needbe)

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  • Problem of instanceOf

    - by eric2323223
    Hi, could anyone tell me why this code won't compile? public boolean isOf(Class clazz, Object obj){ if(obj instanceof clazz){ return true; }else{ return false; } } Why I can't pass a class variable to instanceOf? Thanks in advance.

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  • Strage character encoding problem with Eclipse / Spring / Tomcat 6

    - by Czar
    Hi, I have been trying things all da but can't get a proper solution. My problem is: I am developing a Spring MVC based app in my local Tomcat. My MYSQl database has UTF-8 encoding set, all content in there displays properly when using phpMyAdmin. Also the output in LOG files using log4j in catalina.out works fine. My JSP pages are configured by <!-- encoding --> <%@ page contentType="text/html; charset=UTF-8" %> <%@ page pageEncoding="UTF-8" %> Also showing data on my JSP works fine. I can also send data from my Controller without any DB intereference using special chars, e.g. String str = "UTF-8 Test: Ä Ö Ü ß è é â"; logger.debug(str); mav.addObject("utftest", str); That displays correctly in log and on jsp page in browser. BUT: When having special chars directly in my JSP file, e.g. for text in headers, this does not work. FF and Google Chrome display strange chars but report the page to be UTF-8. When switching to Latin, the chars just get more and more strange. Same problem when showing text tokens from my messages.properties file, although Eclipse says when right-clicking that UTF-8 will be used. I am a little it lost and don't know where to check now. Summary: DB storage is fine DB output on JSP is fine Output on JSP directly form controller is fine even reading in form forms is fine .properties files and JSP text is not fine !!! Any ideas? I really appreciate and tips.

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  • How can I load file into web app through certain periods?

    - by Elena
    Hi all! I have next task: I need to load the same file into my web app several times, for example - twice a day! Suppose in that file I have information, that changes, and I need to load this info into my app to change the statistics for example. How can I load file several times (twice an hour, or twice a day)? What should I use? Is any algorithm to do that? I am not allowed to use external libraries like Quartz Scheduler. So I need to do it with Thread and/or Timer. Can anybody give me some example or algorithm how to do it. Where can I create the entry point to my Thread, can I do it in managed bean or I need some sort of filter/listener/servlet. I works with jsf and richFaces. Maybe in this technologies there are some algorithms to solve my problem. Any ideas? Thanks very much for help!

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  • Call methods in main method

    - by Niloo
    this is my main method that gets 3 integers from command line and I parse then in my validating method. However I have one operation method that calls 3 other methods, but i don't know what type of data and howmany I have to put in my operatinMethod() " cuase switch only gets one); AND also in my mainMethod() for calling the operationMehod(); itself? please let me know if i'm not clear? Thanx! main method: public class test { // Global Constants final static int MIN_NUMBER = 1; final static int MAX_PRIME = 10000; final static int MAX_FACTORIAL = 12; final static int MAX_LEAPYEAR = 4000; //Global Variables static int a,b,c; public static void main (String[] args) { for(int i =0; i< args.length; i++){} if(validateInput(args[0],args[1],args[2])){ performOperations(); } } //Validate User Input public static boolean validateInput(String num1,String num2,String num3){ boolean isValid = false; try{ try{ try{ a = Integer.parseInt(num1); if(!withinRange(a,MIN_NUMBER, MAX_PRIME)) { System.out.println("The entered value " + num1 +" is out of range [1 TO 10000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num1 + " is not a valid integer. Please try again."); } b = Integer.parseInt(num2); if(!withinRange(b,MIN_NUMBER, MAX_FACTORIAL)) { System.out.println("The entered value " + num2 +" is out of range [1 TO 12]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num2 + " is not a valid integer. Please try again."); } c = Integer.parseInt(num3); if(!withinRange(c,MIN_NUMBER, MAX_LEAPYEAR)) { System.out.println("The entered value " + num3 +" is out of range [1 TO 4000]."); } isValid = true; } catch(Exception ex) { System.out.println("The entered value " + num3 + " is not a valid integer. Please try again."); } return isValid; } //Check the value within the specified range private static boolean withinRange(int userInput ,int min, int max){ boolean isInRange = true; if(userInput < min || userInput > max){ isInRange = false; } return isInRange; } //Perform operations private static void performOperations(int userInput) { switch(userInput) { case 1: // count Prime numbers countPrimes(a); break; case 2: // Calculate factorial getFactorial(b); break; case 3: // find Leap year isLeapYear(c); break; } } // Verify Prime Number private static boolean isPrime(int prime) { for(int i = 2; i <= Math.sqrt(prime) ; i++) { if ((prime % i) == 0) { return false; } } return true; } // Calculate Prime private static int countPrimes(int userInput){ int count =0; for(int i=userInput; i<=MAX_PRIME; i++) { if(isPrime(i)){ count++; } } System.out.println("Exactly "+ count + " prime numbers exist between "+ a + " and 10,000."); return count; } // Calculate the factorial value private static int getFactorial(int userInput){ int ans = userInput; if(userInput >1 ){ ans*= (getFactorial(userInput-1)); //System.out.println("The value of "+ b +"! is "+ getFactorial(userInput)); } return ans; } // Determine whether the integer represents a leap year private static boolean isLeapYear(int userInput){ if (userInput % 4 == 0 && userInput % 400 == 0 && userInput % 100 ==0){ System.out.println("The year "+ c +" is a leap year"); } else { System.out.println("The year "+ c +" is a not leap year"); } return false; } }

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  • What can I access in Androids Native libraries? And How?

    - by Donal Rafferty
    I am completely new to the NDK. I have done a couple of the tutorials including the hello from jni one and another one that calculates the sum of two numbers. They involved using cygwin and the ndk to create the library so file and I have a bit of a grasp on how to insert my own libraries into the libraries layer of Android. I have now been asked to access the native libraries on Android and see what I can use them for. My question is can I do this? The STABLE-APIS.txt document is a bit vague and mentions the following as Stable C++ API's in Android 1.5 cstddef new utility stl_pair.h Does that mean I can access them? If so then how do I go about it? I dont think that following the tutorials I have already done would be any help? Any pointers on how to do this or links to tutorials etc.. would be greatly appreciated

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  • Android application transparency and window sizing at root level

    - by ajoburg
    Is it possible to create an application with a transparent background on the root task such that you can see the task running beneath it when it is part of a separate stack? Alternatively, is it possible to run an application so the window of the root task is only a portion of the screen instead of the whole screen? I understand how the transparency and window sizing is done with activities that are not the root task and this works fine. However, the root task of an activity seems to always fill the whole screen and be black even when a transparent theme is applied to the application object in the manifest file. ApplicationManifest.xml: <application android:icon="@drawable/icon" android:label="@string/app_name" android:debuggable="true" android:theme="@style/Theme.Transparent"> Styles.xml <resources> <style name="Theme.Transparent"> <item name="android:windowIsTranslucent">true</item> <item name="android:windowNoTitle">true</item> <item name="android:windowBackground">@drawable/ transparent_background</item> <item name="android:windowAnimationStyle">@android:style/ Animation.Translucent</item> <item name="android:colorForeground">#fff</item> <item name="android:windowIsFloating">true</item> <item name="android:gravity">bottom</item> </style> </resources> Colors.xml <resources> <drawable name="transparent_background">#00000000</drawable> </resources>

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  • Paging of images in blackberry

    - by Maneesh
    How to display images in the form of pages where only one page is displayed at a time on blackberry screen. On scrolling down subsequent images will load at run time. So that loading of images do not consume time at startup.

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  • Creating GUI for Bantumi game

    - by owca
    I've written backend for simple Bantumi game. Now I'd like to create a simple GUI for it, so that it would look like this : How to start ? What layout should I use, and what type of component each element should be? Classes : Basket Player Game Main Shared

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  • Expandable listview Refreshing

    - by Sam97305421562
    Hi, I am using expandable listview i need to refresh as i am searching the list only for parent.I have searched for tutorial in which i can set visibility only for some parent but not all the expandable listview object . Thanks in advance.

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  • hibernate column uniqueness question

    - by Seth
    I'm still in the process of learning hibernate/hql and I have a question that's half best practices question/half sanity check. Let's say I have a class A: @Entity public class A { @Id @GeneratedValue(strategy=GenerationType.AUTO) private Long id; @Column(unique=true) private String name = ""; //getters, setters, etc. omitted for brevity } I want to enforce that every instance of A that gets saved has a unique name (hence the @Column annotation), but I also want to be able to handle the case where there's already an A instance saved that has that name. I see two ways of doing this: 1) I can catch the org.hibernate.exception.ConstraintViolationException that could be thrown during the session.saveOrUpdate() call and try to handle it. 2) I can query for existing instances of A that already have that name in the DAO before calling session.saveOrUpdate(). Right now I'm leaning towards approach 2, because in approach 1 I don't know how to programmatically figure out which constraint was violated (there are a couple of other unique members in A). Right now my DAO.save() code looks roughly like this: public void save(A a) throws DataAccessException, NonUniqueNameException { Session session = sessionFactory.getCurrentSession(); try { session.beginTransaction(); Query query = null; //if id isn't null, make sure we don't count this object as a duplicate if(obj.getId() == null) { query = session.createQuery("select count(a) from A a where a.name = :name").setParameter("name", obj.getName()); } else { query = session.createQuery("select count(a) from A a where a.name = :name " + "and a.id != :id").setParameter("name", obj.getName()).setParameter("name", obj.getName()); } Long numNameDuplicates = (Long)query.uniqueResult(); if(numNameDuplicates > 0) throw new NonUniqueNameException(); session.saveOrUpdate(a); session.getTransaction().commit(); } catch(RuntimeException e) { session.getTransaction().rollback(); throw new DataAccessException(e); //my own class } } Am I going about this in the right way? Can hibernate tell me programmatically (i.e. not as an error string) which value is violating the uniqueness constraint? By separating the query from the commit, am I inviting thread-safety errors, or am I safe? How is this usually done? Thanks!

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  • Calling web services from your JSF code

    - by Abel Morelos
    Let's say that you have a presentation tier in JSF, and that your business tier is accessed using web services. How would you call your web services from JSF? I was considering to have my backing beans to call the web services, but I just though I could use Ajax with JSF in order to connect to the web services. What would you choose and why? Any other choice you could recommend? Thanks.

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  • Getting message in android app: Binary XML file line #2: You must supply a layout_width attribute.

    - by opike
    I'm trying to use a ListView inside of a RelativeLayout but when I run my app I get a runtimeexception with the message: Binary XML file line #2: You must supply a layout_width attribute. I tried putting layout_width attributes in every conceivable place in the xml resource files but so far no luck. I attempt to populate the listview with this line of code: setListAdapter(new ArrayAdapter(this, R.layout.tablerow3, R.id.label, items)); Here's the tablerow3.xml contents: <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"> android:layout_width="20dp" android:layout_height="5dp" android:id="@+id/tablerow01"> <Label android:id="@+id/label01" android:layout_width="5dp" android:layout_height="5dp" android:textColor="@color/solid_white" android:singleLine="true"/> <Label android:id="@+id/label02" android:layout_width="5dp" android:layout_height="5dp" android:textColor="@color/solid_white" android:singleLine="true"/> </LinearLayout> Here's the xml that contains the RelativeLayout(forex2.xml): <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent"> <Button android:text="Static Button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:id="@+id/button_id"> </Button> <Spinner android:id="@+id/spinner1" android:layout_width="match_parent" android:layout_toRightOf="@id/button_id" android:layout_alignParentTop="true" android:layout_height="wrap_content" android:drawSelectorOnTop="true" /> <ListView android:id="@android:id/list" android:layout_width="5dp" android:layout_height="5dp" android:layout_alignParentBottom="true" /> <!-- android:layout_width="wrap_content" android:layout_height="wrap_content" --> </RelativeLayout>

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  • request parameter is taking null value in servlets

    - by Dusk
    Hi, I want to know how can I get the value of the request parameters "j_username" and "j_password"? After successfully login using form based authentication, I want my servlet to get the value of parameters "j_username" and "j_password", but I'm getting null as the value in both parameters. Could anyone please tell me how can I get the actual value of both paramters? Servlets class : package foo; import javax.servlet.http.*; import javax.servlet.*; public class RequestHandler extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) { try { String user = request.getParameter("j_username"); String password = request.getParameter("j_password"); response.getWriter().println(user+" "+password); } catch(Exception e) { e.printStackTrace(); } } } output: null null

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  • httpClient proxy support in apache commons 3.1

    - by user1173339
    I am using apache commons 3.1 to implement httpClient with proxy support. I am trying to connect to a remote host through proxy. The proxy server is configured without any authentication, however the the remote host is configured with authentication. When I am passing the proxy parameters through properties file, it gives warning while execution: WARN - Required proxy credentials not available for BASIC @xx.xx.xx.xx WARN - Preemptive authentication requested but no default proxy credentials availble But the execution goes ahead. On the other hand when I am passing the proxy parameters through the JVM arguments then the again the same warning is given and the execution is stopped. Is there any specific reason for this behavior? Is there any difference in passing the proxy parameters through properties file and through JVM arg? Here is the code: if(System.getProperty("http.proxyHost") != null && System.getProperty("http.proxyPort") != null) { httpClient.getHostConfiguration().setProxy(System.getProperty("http.proxyHost"), Integer.parseInt(System.getProperty("http.proxyPort"))); } else if(AMXAdminTask.props.getProperty("http.proxyHost") != null && AMXAdminTask.props.getProperty("http.proxyPort") != null) { httpClient.getHostConfiguration().setProxy(Propfile.props.getProperty("http.proxyHost"), Integer.parseInt(Propfile.props.getProperty("http.proxyPort"))); }

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  • Repackaging Jasper-Reports into an application specific OSGi bundle, legal or not?

    - by Chris
    Hi, I wanted to ask (probably a silly) question regarding the packaging of existing open-source components as OSGi bundles (more specifically Jasper Reports). I have an application that I am converting from a monolithic jar-hell type architecture to something more moduler and OSGi is my weapon of choice. There are various modules I have in mind but one of the modules is a reporting module. My own reporting module will be a jar file containing my code that should reference a Jasper Reports bundle. Trouble is, Jasper reports depends on far far too many libraries and is quite monolithic in its own right. I therefore wish to build my own Jasper Reports bundle but this is where I start getting confused about the legality of repackaging. I don't plan to re-compile but I do plan to re-bundle removing known items that I do not require. Can anyone offer advice on whether I am permitted to repackage (not recompile or extend) open-source libraries into OSGi bundles without falling foul of 'derivative works' clause of LGPL? I noticed that Groovy seems to offer some monolithic jars that include all dependancies and actually goes so far as to re-arrange the packages of its dependancies so that there are no namespace conflicts. This seems to me to be a violation of the license but if anyone can reassure me that this is legal then I would feel safer about my less intrusive custom-bundling of Jasper reports. Thanks for your time, Chris

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  • How can I turn a string of text into a BigInteger representation for use in an El Gamal cryptosystem

    - by angstrom91
    I'm playing with the El Gamal cryptosystem, and my goal is to be able to encipher and decipher long sequences of text. I have come up with a method that works for short sequences, but does not work for long sequences, and I cannot figure out why. El Gamal requires the plaintext to be an integer. I have turned my string into a byte[] using the .getBytes() method for Strings, and then created a BigInteger out of the byte[]. After encryption/decryption, I turn the BigInteger into a byte[] using the .toByteArray() method for BigIntegers, and then create a new String object from the byte[]. This works perfectly when i call ElGamalEncipher with strings up to 129 characters. With 130 or more characters, the output produced is garbled. Can someone suggest how to solve this issue? Is this an issue with my method of turning the string into a BigInteger? If so, is there a better way to turn my string of text into a BigInteger and back? Below is my encipher/decipher code. public static BigInteger[] ElGamalEncipher(String plaintext, BigInteger p, BigInteger g, BigInteger r) { // returns a BigInteger[] cipherText // cipherText[0] is c // cipherText[1] is d BigInteger[] cipherText = new BigInteger[2]; BigInteger pText = new BigInteger(plaintext.getBytes()); // 1: select a random integer k such that 1 <= k <= p-2 BigInteger k = new BigInteger(p.bitLength() - 2, sr); // 2: Compute c = g^k(mod p) BigInteger c = g.modPow(k, p); // 3: Compute d= P*r^k = P(g^a)^k(mod p) BigInteger d = pText.multiply(r.modPow(k, p)).mod(p); // C =(c,d) is the ciphertext cipherText[0] = c; cipherText[1] = d; return cipherText; } public static String ElGamalDecipher(BigInteger c, BigInteger d, BigInteger a, BigInteger p) { //returns the plaintext enciphered as (c,d) // 1: use the private key a to compute the least non-negative residue // of an inverse of (c^a)' (mod p) BigInteger z = c.modPow(a, p).modInverse(p); BigInteger P = z.multiply(d).mod(p); byte[] plainTextArray = P.toByteArray(); String output = null; try { output = new String(plainTextArray, "UTF8"); } catch (Exception e) { } return output; }

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  • Socket server with multiple clients, sending messages to many clients without hurting liveliness

    - by Karl Johanson
    I have a small socket server, and I need to distribute various messages from client-to-client depending on different conditionals. However I think I have a small problem with livelyness in my current code, and is there anything wrong in my approach: public class CuClient extends Thread { Socket socket = null; ObjectOutputStream out; ObjectInputStream in; CuGroup group; public CuClient(Socket s, CuGroup g) { this.socket = s; this.group = g; out = new ObjectOutputStream(this.socket.getOutputStream()); out.flush(); in = new ObjectInputStream(this.socket.getInputStream()); } @Override public void run() { String cmd = ""; try { while (!cmd.equals("client shutdown")) { cmd = (String) in.readObject(); this.group.broadcastToGroup(this, cmd); } out.close(); in.close(); socket.close(); } catch (Exception e) { System.out.println(this.getName()); e.printStackTrace(); } } public void sendToClient(String msg) { try { this.out.writeObject(msg); this.out.flush(); } catch (IOException ex) { } } And my CuGroup: public class CuGroup { private Vector<CuClient> clients = new Vector<CuClient>(); public void addClient(CuClient c) { this.clients.add(c); } void broadcastToGroup(CuClient clientName, String cmd) { Iterator it = this.clients.iterator(); while (it.hasNext()) { CuClient cu = (CuClient)it.next(); cu.sendToClient(cmd); } } } And my main-class: public class SmallServer { public static final Vector<CuClient> clients = new Vector<CuClient>(10); public static boolean serverRunning = true; private ServerSocket serverSocket; private CuGroup group = new CuGroup(); public void body() { try { this.serverSocket = new ServerSocket(1337, 20); System.out.println("Waiting for clients\n"); do { Socket s = this.serverSocket.accept(); CuClient t = new CuClient(s,group); System.out.println("SERVER: " + s.getInetAddress() + " is connected!\n"); t.start(); } while (this.serverRunning); } catch (IOException ex) { ex.printStackTrace(); } } public static void main(String[] args) { System.out.println("Server"); SmallServer server = new SmallServer(); server.body(); } } Consider the example with many more groups, maybe a Collection of groups. If they all synchronize on a single Object, I don't think my server will be very fast. I there a pattern or something that can help my liveliness?

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  • alternatedocroot

    - by ring bearer
    Using Sun Glassfish Enterprise server v2.1.1 I am using "alternatedocroot" via sun-web.xml for my web application to abstract out static content from actual deploy-able code (EAR/WAR) What I have is a cluster of two server instances distributed across two physical hosts - HOST1 and HOST2. "alternatedocroot" points to /data/static-content/ on both HOST1 and HOST2. Would DAS (Domain application server )take care of syncing /data/static-content between HOST1 and HOST2 if I use syncinstances=true option while starting up the cluster? Thanks!

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  • Parsing complex string using regex

    - by wojtek_z
    My regex skills are not very good and recently a new data element has thrown my parser into a loop Take the following string "+USER=Bob Smith-GROUP=Admin+FUNCTION=Read/FUNCTION=Write" Previously I had the following for my regex : [+\\-/] Which would turn the result into USER=Bob Smith GROUP=Admin FUNCTION=Read FUNCTION=Write FUNCTION=Read But now I have values with dashes in them which is causing bad output New string looks like "+USER=Bob Smith-GROUP=Admin+FUNCTION=Read/FUNCTION=Write/FUNCTION=Read-Write" Which gives me the following result , and breaks the key = value structure. USER=Bob Smith GROUP=Admin FUNCTION=Read FUNCTION=Write FUNCTION=Read Write Can someone help me formulate a valid regex for handling this or point me to some key / value examples. Basically I need to be able to handle + - / signs in order to get combinations.

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  • Writing a Servlet that checks to see if JSP's exist and forwards to another JSP if they aren't

    - by Omar Kooheji
    I've beeb tasked with writing a servlet that intercepts a call to and JSP in a specific directoy, check that the file exists and if it does just forwarding to that file, if if doesn't I'm to forward to a default JSP. I've setup the web.xml as follows: <servlet> <description>This is the description of my J2EE component</description> <display-name>This is the display name of my J2EE component</display-name> <servlet-name>CustomJSPListener</servlet-name> <servlet-class> ... CustomJSPListener</servlet-class> <load-on-startup>1</load-on-startup> </servlet> ... <servlet-mapping> <servlet-name>CustomJSPListener</servlet-name> <url-pattern>/custom/*</url-pattern> </servlet-mapping> And the doGet method of the servlet is as follows: public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { logger.debug(String.format("Intercepted a request for an item in the custom directory [%s]",request.getRequestURL().toString())); String requestUri = request.getRequestURI(); // Check that the file name contains a text string if (requestUri.toLowerCase(Locale.UK).contains("someText")){ logger.debug(String.format("We are interested in this file [%s]",requestUri)); File file = new File(requestUri); boolean fileExists = file.exists(); logger.debug(String.format("Checking to see if file [%s] exists [%s].",requestUri,fileExists)); // if the file exists just forward it to the file if (fileExists){ getServletConfig().getServletContext().getRequestDispatcher( requestUri).forward(request,response); } else { // Otherwise redirect to default.jsp getServletConfig().getServletContext().getRequestDispatcher( "/custom/default.jsp").forward(request,response); } } else { // We aren't responsible for checking this file exists just pass it on to the requeseted jsp getServletConfig().getServletContext().getRequestDispatcher( requestUri).forward(request,response); } } This seems to result in an error 500 from tomcat, I think this is because the servlet is redirecting to the same folder which is then being intercepted again by the servlet, resulting in an infinite loop. Is there a better way to do this? I'm lead to believe that I could use filters to do this, but I don't know very much about them.

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