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  • Limit TCP requests per IP

    - by asmo
    Hello! I'm wondering how to limit the TCP requests per client (per specific IP) in Java. For example, I would like to allow a maximum of X requests per Y seconds for each client IP. I thought of using static Timer/TimerTask in combination with a HashSet of temporary restricted IPs. private static final Set<InetAddress> restrictedIPs = Collections.synchronizedSet(new HashSet<InetAddress>()); private static final Timer restrictTimer = new Timer(); So when a user connects to the server, I add his IP to the restricted list, and start a task to unrestrict him in X seconds. restrictedIPs.add(socket.getInetAddress()); restrictTimer.schedule(new TimerTask() { public void run() { restrictedIPs.remove(socket.getInetAddress()); } }, MIN_REQUEST_INTERVAL); My problem is that at the time the task will run, the socket object may be closed, and the remote IP address won't be accessible anymore... Any ideas welcomed! Also, if someone knows a Java-framework-built-in way to achieve this, I'd really like to hear it.

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  • Understanding Hibernate saveOrUpdate and the Persistence Life Cycle

    - by Stephano
    The books that I've read regarding hibernate are, at best, reference tomes. They very seldom have good code examples, so I tend to use online resources for those needs. However, I've always had a problem understanding the basic idea of hibernate persistence. I've read the books and understand the concepts, but in practice, I often see results that I don't understand. Perhaps you all can help, as you have in the past. Let's look at a simple example of a dog and a cat that are friends. This isn't a rare occurrence. It also has the benefit of being much more interesting than my business case. We want a function called "saveFriends" that takes a dog name and a cat name. We'll save the Dog and then the Cat. For this example to work, the cat is going to have a reference back to the dog. I understand this isn't an ideal example, but it's cute and works for our purposes. FriendService.java public int saveFriends(String dogName, String catName) { Dog fido = new Dog(); Cat felix = new Cat(); fido.name = dogName; fido = animalDao.saveDog(fido); felix.name = catName; [ex.A]felix.friend = fido; [ex.B]felix.friend = animalDao.getDogByName(dogName); animalDao.saveCat(felix); } AnimalDao.java (extends HibernateDaoSupport) public Dog saveDog(Dog dog) { getHibernateTemplate().saveOrUpdate(dog); return dog } public Cat saveCat(Cat cat) { getHibernateTemplate().saveOrUpdate(cat); return cat; } public Dog getDogByName(String name) { return (Dog) getHibernateTemplate().find("from Dog where name=?", name).get(0); } Now, assume for a minute that I would like to use either example A or example B to save my friend. Is one better than the other to use? I'll understand if neither of those examples work, but please explain why.

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  • Where is the taglib definition of PrimeFaces 4?

    - by Michael Wölm
    I am looking around how to define custom components in JSF. According to the Java EE tutorial, any custom component needs to be described in a taglib. When I take a look into the PrimeFaces source, I cannot find any taglib file or any hint where the namespace is bound and the available components are defined. I am adding primefaces jar to my dependencies, adding xmlns:p="http://primefaces.org/ui to the xml namespace, defining some primfaces components on my page and it works... Ok, but neither I can find the related taglib in the source or binary package nor my IDE (IntelliJ) is able to find where "xmlns:p="http://primefaces.org/ui" is pointing to. Therefore, code completion is also not possible. (all other mojarra taglibs are found.) Is it possible that PrimeFaces is defining the taglib via annotations directly in Java classes or is it generating it during runtime? I can easily find the UIComponents, primefaces defines in its source, but the configuration of the taglib seems to be missing. I am sure I just don't know how PrimeFaces is doing it, but the javaeetutorial is not describing any other opportunity than defining a ...-taglib.xml

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  • Spring: Bean fails to read off values from external Properties file when using @Value annotation

    - by daydreamer
    XML Configuration <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <util:properties id="mongoProperties" location="file:///storage/local.properties" /> <bean id="mongoService" class="com.business.persist.MongoService"></bean> </beans> and MongoService looks like @Service public class MongoService { @Value("#{mongoProperties[host]}") private String host; @Value("#{mongoProperties[port]}") private int port; @Value("#{mongoProperties[database]}") private String database; private Mongo mongo; private static final Logger LOGGER = LoggerFactory.getLogger(MongoService.class); public MongoService() throws UnknownHostException { LOGGER.info("host=" + host + ", port=" + port + ", database=" + database); mongo = new Mongo(host, port); } public void putDocument(@Nonnull final DBObject document) { LOGGER.info("inserting document - " + document.toString()); mongo.getDB(database).getCollection(getCollectionName(document)).insert(document, WriteConcern.SAFE); } I write my MongoServiceTest as public class MongoServiceTest { @Autowired private MongoService mongoService; public MongoServiceTest() throws UnknownHostException { mongoRule = new MongoRule(); } @Test public void testMongoService() { final DBObject document = DBContract.getUniqueQuery("001"); document.put(DBContract.RVARIABLES, "values"); document.put(DBContract.PVARIABLES, "values"); mongoService.putDocument(document); } and I see failures in tests as 12:37:25.224 [main] INFO c.s.business.persist.MongoService - host=null, port=0, database=null java.lang.NullPointerException at com.business.persist.MongoServiceTest.testMongoService(MongoServiceTest.java:40) Which means bean was not able to read the values from local.properties local.properties ### === MongoDB interaction === ### host="127.0.0.1" port=27017 database=contract How do I fix this? update It doesn't seem to read off the values even after creating setters/getters for the fields. I am really clueless now. How can I even debug this issue? Thanks much!

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  • Problem painting JLabel class to another JPanel class

    - by jjpotter
    I have created a class that extends JLabel to use as my object moving around a JPanel for a game. import javax.swing.*; public class Head extends JLabel { int xpos; int ypos; int xvel; int yvel; ImageIcon chickie = new ImageIcon("C:\\Users\\jjpotter.MSDOM1\\Pictures\\clavalle.jpg"); JLabel myLabel = new JLabel(chickie); public Head(int xpos, int ypos, int xvel, int yvel){ this.xpos = xpos; this.ypos = ypos; this.xvel = xvel; this.yvel = yvel; } public void draw(){ myLabel.setLocation(xpos, ypos); } public double getXpos() { return xpos; } public double getYpos() { return ypos; } public int getXvel() { return xvel; } public int getYvel() { return yvel; } public void setPos(int x, int y){ xpos = x; ypos = y; } } I am then trying to add it onto my JPanel. From here I will randomly have it increment its x and y coordinates to float it around the screen. I can not get it to paint itself onto the JPanel. I know there is a key concept I am missing here that involves painting components on different panels. Here is what I have in my GamePanel class import java.awt.Dimension; import java.util.Random; import javax.swing.*; public class GamePanel extends JPanel { Random myRand = new Random(); Head head = new Head(20,20,0,0); public GamePanel(){ this.setSize(new Dimension(640, 480)); this.add(head); } } Any suggestions on how to get this to add to the JPanel? Also, is this a good way to go about having the picture float around the screen randomly for a game?

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  • we would like the user to be able to pick a file from native file system and drag & drop it to our a

    - by user261740
    We have an existing java desktop application which starts, when user click on our application icon (placed on desktop) OR double click on executable(.exe). It opens the frame which allows user to select the file from native file system and uploads it to the server. Now we would like to facilitate user, that he can pick a file from windows explorer and drag it to the "shortcut / Application icon" & drop it on the "shortcut / Application icon" on the desktop. This would start the uploading of that file on the server. we need to capture the action of "drop" and launch on shortcut.. which may be completely not related to java, it can be very generic to any application. We are using JSmooth to build an executable from jar and NSIS for installer purpose. I would like to know.. How we can launch the application if user drops local file onto the system icon ? How we get the absolute path of file name which has been dropped onto the executable ?

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  • Android: Help with tabs view

    - by James
    So I'm trying to build a tabs view for an Android app, and for some reason I get a force close every time I try to run it on the emulator. When I run the examples, everything shows fine, so I went as far as to just about copy most of the layout from the examples(a mix of Tabs2.java and Tabs3.java), but for some reason it still wont run, any ideas? Here is my code(List1.class is a copy from the examples for testing purposes). It all compiles fine, just gets a force close the second it starts: package com.jvavrik.gcm; import android.app.TabActivity; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.TabHost; import android.widget.TextView; public class GCM extends TabActivity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); final TabHost tabHost = getTabHost(); tabHost.addTab(tabHost.newTabSpec("tab1") .setIndicator("g", getResources().getDrawable(R.drawable.star_big_on)) .setContent(new Intent(this, List1.class))); tabHost.addTab(tabHost.newTabSpec("tab2") .setIndicator("C") .setContent(new Intent(this, List1.class)) ); tabHost.addTab(tabHost.newTabSpec("tab3") .setIndicator("S") .setContent(new Intent(this, List1.class)) ); tabHost.addTab(tabHost.newTabSpec("tab4") .setIndicator("A") .setContent(new Intent(this, List1.class)) ); } }

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  • Issue reading in a cell from Excel with Apache POI

    - by Nick
    I am trying to use Apache POI to read in old (pre-2007 and XLS) Excel files. My program goes to the end of the rows and iterates back up until it finds something that's not either null or empty. Then it iterates back up a few times and grabs those cells. This program works just fine reading in XLSX and XLS files made in Office 2010. I get the following error message: Exception in thread "main" java.lang.NumberFormatException: empty String at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source) at java.lang.Double.parseDouble(Unknown Source) at the line: num = Double.parseDouble(str); from the code: str = cell.toString(); if (str != "" || str != null) { System.out.println("Cell is a string"); num = Double.parseDouble(str); } else { System.out.println("Cell is numeric."); num = cell.getNumericCellValue(); } where the cell is the last cell in the document that's not empty or null. When I try to print the first cell that's not empty or null, it prints nothing, so I think I'm not accessing it correctly.

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  • Class initialization and synchronized class method

    - by nybon
    Hi there, In my application, there is a class like below: public class Client { public synchronized static print() { System.out.println("hello"); } static { doSomething(); // which will take some time to complete } } This class will be used in a multi thread environment, many threads may call the Client.print() method simultaneously. I wonder if there is any chance that thread-1 triggers the class initialization, and before the class initialization complete, thread-2 enters into print method and print out the "hello" string? I see this behavior in a production system (64 bit JVM + Windows 2008R2), however, I cannot reproduce this behavior with a simple program in any environments. In Java language spec, section 12.4.1 (http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html), it says: A class or interface type T will be initialized immediately before the first occurrence of any one of the following: T is a class and an instance of T is created. T is a class and a static method declared by T is invoked. A static field declared by T is assigned. A static field declared by T is used and the reference to the field is not a compile-time constant (§15.28). References to compile-time constants must be resolved at compile time to a copy of the compile-time constant value, so uses of such a field never cause initialization. According to this paragraph, the class initialization will take place before the invocation of the static method, however, it is not clear if the class initialization need to be completed before the invocation of the static method. JVM should mandate the completion of class initialization before entering its static method according to my intuition, and some of my experiment supports my guess. However, I did see the opposite behavior in another environment. Can someone shed me some light on this? Any help is appreciated, thanks.

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  • JDialog setResizable(false) is not working in Window Title Bar Menu

    - by jolonaleur
    JDialog setResizable(false) is not working in Window Title Bar Menu Windows XP SP2 Java JRE 1.6.0_11-b03 Behavior varies. Sometimes, the Maximize and Minimize item on the window menu is disabled and sometimes enabled. Steps to reproduce enabled Maximize and Minimize button: Show the JDialog with setResizable(false) Open another window, say for example Notepad. Right-click on the window title bar of Notepad and click Maximize. Go to your JDialog and right click on the window title bar. Maximize window is enabled. Likewise, to disable the Maximize item for the JDialog, go to the maximized Notepad window and right click on title bar. Maximize item is disabled in the Notepad window. Go the your JDialog and right click on the title bar, notice that the Maximize item is also disabled. Note that my application can not use the defaultLookAndFeel method of java dialogs. The bug report related to this was for Solaris OS but that was already ages ago. bug report Is there any workaround? Thanks.

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  • Creation of Objects: Constructors or Static Factory Methods

    - by Rachel
    I am going through Effective Java and some of my things which I consider as standard are not suggested by the book, for instance creation of object, I was under the impression that constructors are the best way of doing it and books says we should make use of static factory methods, I am not able to few some advantages and so disadvantages and so am asking this question, here are the benefits of using it. Advantages: One advantage of static factory methods is that, unlike constructors, they have names. A second advantage of static factory methods is that, unlike constructors, they are not required to create a new object each time they’re invoked. A third advantage of static factory methods is that, unlike constructors, they can return an object of any subtype of their return type. A fourth advantage of static factory methods is that they reduce the verbosity of creating parameterized type instances. I am not able to understand this advantage and would appreciate if someone can explain this point Disadvantages: The main disadvantage of providing only static factory methods is that classes without public or protected constructors cannot be subclassed. A second disadvantage of static factory methods is that they are not readily distinguishable from other static methods.I am not getting this point and so would really appreciate some explanation. Reference: Effective Java, Joshua Bloch, Edition 2, pg: 5-10 Also, How to decide to use whether to go for Constructor or Static Factory Method for Object Creation ?

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  • How to properly set JavaMail timeout setting

    - by user286149
    I am using JavaMail to connect to a POP3 server. Further, I set the following properties, so that JavaMail won't wait to long if an email server doesn't respond: props.setProperty("mail.pop3.connectionpooltimeout", "3000"); props.setProperty("mail.pop3.connectiontimeout", "3000"); props.setProperty("mail.pop3.timeout", "3000"); However, in some cases the timeout works properly but sometimes JavaMail freezes for minutes(!) with the following debug message: DEBUG POP3: connecting to host "pop3.yahoo.com", port 110, isSSL false Changing ports or protocols (SSL, TLS..) has no effect. I assume that the host simply doesn't exist. For example, if I poll pop3.yahoo.com instead of pop.mail.yahoo.com (which would be the right host name), I have to wait very long til a timeout exception occurs. After several minutes, I get the following exception and the application continues to run: java.net.ConnectException: Operation timed out pop3.yahoo.com seems to exist but won't respond: localhost:~ me$ ping pop3.yahoo.com PING pop3.yahoo.com (206.190.46.10): 56 data bytes Request timeout for icmp_seq 0 Request timeout for icmp_seq 1 Request timeout for icmp_seq 2 Request timeout for icmp_seq 3 ^C You might be asking why I use pop3.yahoo.com instead of pop.mail.yahoo.com. Well, I simply wanted to test what happens if the user of my application inserts a wrong host name. I believe that this issue is related to this report http://www.opensubscriber.com/message/[email protected]/180946.html where the poster claims that the problem occurs if the email server closes the connection. JavaMail then seems to wait very long (don't know why). Since the issue wasn't resolved in the link I posted: Does somebody know how to fix or at least debug this? Any help would be really appreciated!

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  • How to link different Servlet together?

    - by Harry Pham
    First of all, I did not use Spring MVC. :) :) Just want to get it out first. Now what I have is different JSP pages that making calls to different Servlets. All the pieces work great individually but I kind of need to link them together. If all of jsp pages make GET request then it would be easy, since I would just pass a type via the web address, and on my servlet side, I would just enumerated through all the parameter, determine which type is it, and delegate to the right servlet. But not all jsp pages make GET request, some make POST request via form. Let see example A.jsp $.getJSON('GenericServlet?type=A', ... GenericServlet.java String type = request.getParameter("type"); if(type.equals("A")){ //Somehow delegate to Servlet A (Not sure how to do that yet :)) } but in B.jsp I would have something like this B.jsp <form action="GenericServlet" method="post"> <table border=0 cellspacing=10 cellpadding=0> <tr> <td>User Name:</td> <td><input type="text" name="username" size=22/></td> </tr> <tr> <td>Password:</td> <td><input type="password" name="password" size=22/></td> </tr> </table> <input type="submit" value="Create User" /> </form> It kind of hard for me to determine in GenericServlet.java that this need to go to servletB

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  • GlassFish 3: how do you change the (default) logging format?

    - by Kawu
    The question originated from here: http://www.java.net/forum/topic/glassfish/glassfish/configuring-glassfish-logging-format - without an answer. The default GlassFish 3 logging format of is very annoying, much too long. [#|2012-03-02T09:22:03.165+0100|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=113;_ThreadName=AWT-EventQueue-0;| MESSAGE... ] This is just a horrible default IMO. The docs just explain all the fields, but not how to change the format: http://docs.oracle.com/cd/E18930_01/html/821-2416/abluk.html Note, that I deploy SLF4J along with my webapp which should pick up the format as well. How do you change the logging format? FYI: The links here are outdated: Install log formater in glassfish... The question here hasn't been answered: How to configure GlassFish logging to show milliseconds in timestamps?... The posting here resulted in nothing: http://www.java.net/forum/topic/glassfish/glassfish/cant-seem-configure-... It looks like GlassFish logging configuration is an issue of its own. Can anybody help?

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  • Google AppEngine + Local JUnit Tests + Jersey framework + Embedded Jetty

    - by xamde
    I use Google Appengine for Java (GAE/J). On top, I use the Jersey REST-framework. Now i want to run local JUnit tests. The test sets up the local GAE development environment ( http://code.google.com/appengine/docs/java/tools/localunittesting.html ), launches an embedded Jetty server, and then fires requests to the server via HTTP and checks responses. Unfortunately, the Jersey/Jetty combo spawns new threads. GAE expects only one thread to run. In the end, I end up having either no datstore inside the Jersey-resources or multiple, having different datastore. As a workaround I initialise the GAE local env only once, put it in a static variable and inside the GAE resource I add many checks (This threads has no dev env? Re-use the static one). And these checks should of course only run inside JUnit tests.. (which I asked before: "How can I find out if code is running inside a JUnit test or not?" - I'm not allowed to post the link directly here :-|)

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  • Wrapper class that creates objects at runtime and stores data in an array.

    - by scriptingalias
    I tried making a wrapper class that encapsulates an object, a string (for naming and differentiating the object instance), and an array to store data. The problem I'm having now is accessing this class using methods that determine the "name" of the object and also reading the array containing some random variables. import java.util.Arrays; import java.util.Random; public class WrapperClass { String varName; Object varData; int[] array = new int[10]; public WrapperClass(String name, Object data, int[] ARRAY) { varName = name; varData = data; array = ARRAY; } public static void getvalues() { } public static void main(String[] args) { int[] array = new int[10]; Random random = new Random(3134234); for(int i = 0; i < 10; i++) { for (int c = 0; c < 10; c++) { array[c] = random.nextInt();//randomly creates data } WrapperClass w = new WrapperClass("c" + i, new Object(),array); } } }

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  • Which web framework or technologies would suit me?

    - by Suraj Chandran
    Hi, I had been working on desktop apps and server side(non web) for some time and now I am diving in to web first time. I plan to write a scalable enterprise level app. I have worked with Java, Javascript, Jquery etc. but I absolutely hate jsp. So is there any framework that focuses on developing enterprise level web apps without jsp. I liked Wicket's approach, but I think there is a little lack of support of dynamic html in it and jquery(yes i looked at wiquery). Also I feel making wicket apps scalable would take some sweat. Can Spring MVC, Struts2 etc. help me make with this with just using say Java, JavaScript, and JQuery. Or are there any other options for me like Wicket. Please do forgive if anything above looks insane, I am still working on my understanding with enterprise web apps. NOTE: If you think that I should take a different direction or approach, please do suggest!

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  • Is this the intention behavior in JComboBox? How I can avoid this behavior?

    - by Yan Cheng CHEOK
    I realize that if you are having a same selection in JComboBox, using up/down arrow key, will not help you to navigate the selection around. How I can avoid this behavior? See the below screen shoot /* * To change this template, choose Tools | Templates * and open the template in the editor. */ /* * NewJFrame.java * * Created on May 8, 2010, 7:46:28 PM */ package javaapplication26; /** * * @author yccheok */ public class NewJFrame extends javax.swing.JFrame { /** Creates new form NewJFrame */ public NewJFrame() { initComponents(); /* If you are having 3 same strings here. Using, up/down arrow key, * will not move the selection around. */ this.jComboBox1.addItem("Intel"); this.jComboBox1.addItem("Intel"); this.jComboBox1.addItem("Intel"); } /** This method is called from within the constructor to * initialize the form. * WARNING: Do NOT modify this code. The content of this method is * always regenerated by the Form Editor. */ @SuppressWarnings("unchecked") // <editor-fold defaultstate="collapsed" desc="Generated Code"> private void initComponents() { jComboBox1 = new javax.swing.JComboBox(); setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE); jComboBox1.setEditable(true); javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane()); getContentPane().setLayout(layout); layout.setHorizontalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(105, 105, 105) .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, 158, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(137, Short.MAX_VALUE)) ); layout.setVerticalGroup( layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING) .addGroup(layout.createSequentialGroup() .addGap(63, 63, 63) .addComponent(jComboBox1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE) .addContainerGap(217, Short.MAX_VALUE)) ); pack(); }// </editor-fold> /** * @param args the command line arguments */ public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { public void run() { new NewJFrame().setVisible(true); } }); } // Variables declaration - do not modify private javax.swing.JComboBox jComboBox1; // End of variables declaration }

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  • How to get the compression ratio for a GZipped file ?

    - by Enigma
    Here is how I compressed the data: <%@ page import="javax.servlet.jsp.*,java.io.*,java.util.zip.*" %> <% String encodings = request.getHeader("Accept-Encoding"); PrintWriter outWriter = null; if ((encodings != null) && (encodings.indexOf("gzip") != -1)) { OutputStream outA = response.getOutputStream(); outWriter = new PrintWriter(new GZIPOutputStream(outA), false); response.setHeader("Content-Encoding", "gzip"); int a = response.getBufferSize(); System.out.println("ZIPPED VERSION BF:"+a); } else { System.out.println("UN-ZIPPED VERSION"); outWriter = new PrintWriter(response.getOutputStream(), false); } outWriter.println("<HTML><BODY>"); for(int i=0; i<1000; i++) { outWriter.println(" blah blah blah<br>"); } outWriter.println("</BODY></HTML>"); outWriter.close(); %>

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  • URL equals and checking Internet access

    - by James P.
    On http://java.sun.com/j2se/1.5.0/docs/api/java/net/URL.html it states that: Compares this URL for equality with another object. If the given object is not a URL then this method immediately returns false. Two URL objects are equal if they have the same protocol, reference equivalent hosts, have the same port number on the host, and the same file and fragment of the file. Two hosts are considered equivalent if both host names can be resolved into the same IP addresses; else if either host name can't be resolved, the host names must be equal without regard to case; or both host names equal to null. Since hosts comparison requires name resolution, this operation is a blocking operation. Note: The defined behavior for equals is known to be inconsistent with virtual hosting in HTTP. According to this, equals will only work if name resolution is possible. Since I can't be sure that a computer has internet access at a given time, should I just use Strings to store addresses instead? Also, how do I go about testing if access is available when requested?

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  • Alternatives to static methods on interfaces for enforcing consistency

    - by jayshao
    In Java, I'd like to be able to define marker interfaces, that forced implementations to provide static methods. For example, for simple text-serialization/deserialization I'd like to be able to define an interface that looked something like this: public interface TextTransformable<T>{ public static T fromText(String text); public String toText(); Since interfaces in Java can't contain static methods though (as noted in a number of other posts/threads: here, here, and here this code doesn't work. What I'm looking for however is some reasonable paradigm to express the same intent, namely symmetric methods, one of which is static, and enforced by the compiler. Right now the best we can come up with is some kind of static factory object or generic factory, neither of which is really satisfactory. Note: in our case our primary use-case is we have many, many "value-object" types - enums, or other objects that have a limited number of values, typically carry no state beyond their value, and which we parse/de-parse thousands of time a second, so actually do care about reusing instances (like Float, Integer, etc.) and its impact on memory consumption/g.c. Any thoughts?

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  • What i am doing wrong with Class Overview?

    - by RFM software
    This code not work. Anyone can helpme? .java package rfmsoftware.util.test1; import android.app.Activity; import android.os.Bundle; public class test1 extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button button = (Button)findViewById(R.id.Button01); <---- Error at this line !? } } .xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> <EditText android:id="@+id/EditText01" android:layout_width="wrap_content" android:layout_height="wrap_content" android:ems="10"></EditText> <Button android:id="@+id/Button01" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/Scan"></Button> <View android:id="@+id/View01" android:layout_width="wrap_content" android:layout_height="wrap_content"></View> </LinearLayout> .error Button cannot be resolved to a type (type Java problem) ???

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  • How can I create global context variables in JBOSS?

    - by NobodyMan
    This is a follow-up to a question I posted a while back: "Can I use a single WAR in multiple environments?". I was able to create a single-war solution in Tomcat, but now we are migrating our app to JBoss 4.2 and I can't figure out how to set up global environment variables. In Tomcat 6 this was pretty straightforward: I simply put the following snippet in tomcat/conf/Catalina/myappname.xml: <Context ...> <Environment name="TARGET_ENV" value="DEV" type="java.lang.String" override="false"/> </Context> Then in my app I was able to resolve the environment name with the following: Context context = (Context) InitialContext().lookup("java:comp/env"); String targetEnvironment = (String) context.lookup("TARGET_ENV"); The problem is that I can't find out where/how to place global variables in JBoss. I've tried putting the <Environment> tag in the following files to no avail: server/all/deploy/jboss-web.deployer/context.xml server/default/deploy/jboss-web.deployer/context.xml I know that I can put environment variables in my app's web.xml but that defeats the purpose of having a unified war - I'd still need custom .war's for dev, qa and prod. I'm a JBoss newbie so if there's any additional information that would help just let me know and I'll append to this question. Many thanks! --N

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  • JAXB code generation: how to remove a zero occurrence field?

    - by reef
    Hi all, I use JAXB 2.1 to generate Java classes from several XSD files, and I have a problem related to complex type restriction. On of the restrictions modifies the occurence configuration from minOccurs="0" maxOccurs="unbounded" to minOccurs="0" maxOccurs="0". Thus this field is not needed anymore in the restricted type. But actually JAXB generates the restricted class with a [0..1] cardinality instead of 0. By the way the generation is tuned with <xjc:treatRestrictionLikeNewType / so that a XSD restriction is not mapped to a Java class inheritance. Here is an example: Here is the way a field is defined in a complex type A: <element name="qualifier" type="CR" maxOccurs="unbounded" minOccurs="0"/ Here is the way the same field is restricted in another complex type B that restricts A: <element name="qualifier" type="CR" minOccurs="0" maxOccurs="0"/ In the A generated class I have: @XmlElement(name = "qualifier") protected List<CR qualifiers; And in the B generated class I have: protected CR qualifiers; With my poor understanding of JAXB the absence of the XmlElement annotation tells JAXB not to marshall/unmarshall this field. Am I wrong? If I am right is there a way to tell JAXB not to generate the qualifiers field at all? This would be in my opinion a much better generation as it respects the constraints. Any idea, thougths on the topic? Thanks!!

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  • Google App Engine datastore encoding?

    - by sernaferna
    I'm using the GAE datastore for a Java application, and storing some text that will be in numerous languages. In my servlet, I'm first checking to see if there's any data in the data store, and, if not, I'm creating some, similar to the following: ArrayList<Lang> list = new ArrayList<Lang>(); list.add(new Lang("EN", "English", 1)); list.add(new Lang("ES", "Español", 0)); //more languages here... PersistenceManager pm = PMF.get().getPersistenceManager(); for(Lang l : list) { pm.makePersistent(l); } Since this is using JDO, I guess I should include the relevent parts of the Lang class too: @PersistenceCapable public class Lang { @PrimaryKey private String code; @Persistent private String name; @Persistent private int popularity; // getters & setters & constructors... } However, the non-ASCII characters are giving me grief. I've set my Eclipse project to use the UTF-8 encoding instead of the default Cp1252, so I think I'm okay from that perspective, but when I use the App Engine Data Viewer to look at my data, that Español entry becomes Español, and when I click on it to view it, I get a 500 Server Error. (There are some other entries with right-to-left text that don't even show up in the Data Viewer at all, but one problem at a time...) Is there anything special I can do in my code to set the character encoding, or specify to GAE that the data I'm storing is UTF-8? Or is the problem on the Eclipse side, and is there something I should be doing with my Java code?

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