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Created by Dr. Xi on January 14, 2010 00:28:27    Last update: March 30, 2011 15:37:44
A task that a Java developer does so frequently is to find out where a certain class can be found - to resolve compilation errors, classpath issues, or version conflicts of the same class introduced by multiple class loaders. A long while back I wrote a simple Perl script to perform the task. Later I was informed that there are Swing based Jar Browser and Jars Browser . Then, there are a couple of shell one-liners: # one liner 1 find -name "*.jar" -print0 | xarg... But all of them share the same problem: if a class is in a jar nested in another jar, it cannot be found. Such is the case for a class inside a jar under the WEB-INF/lib directory of a...
Created by voodoo on February 25, 2011 14:00:41    Last update: February 25, 2011 14:03:46
Suddenly my Windows XP failed to boot with this error message on a blank screen: missing or corrupt <windows root>\system32\hal.dll I took out the hard drive, put it in a USB enclosure and attached it to another PC. Then I ran CHKDSK and it fixed some file system errors. But I did find that hal.dll was intact, so hal.dll was not missing or corrupt . It turned out that the file that was really missing was C:\boot.ini . It is a hidden file, so you have to use attrib boot.ini to see it. The file is missing if attrib boot.ini returns nothing (run in the root folder C:\). In my case I reconstructed the boot.ini file: [boot loader] timeout=30 default=multi(0)dis... and changed the attributes back...
Created by James on July 06, 2010 19:35:00    Last update: July 06, 2010 19:35:00
Java has built-in functions to get the basename and dirname for a given file path, but the function names are not so self-apparent. import java.io.File; public class JavaFileD... Results: C:\tmp>java JavaFileDirNameBaseName Dirname: .....
Created by Dr. Xi on June 19, 2010 04:34:01    Last update: June 19, 2010 04:39:13
Java SE 6 contains built-in utilities to generate XML signatures. This is an example that generates XML signatures using a Java keystore. It has options to generate signature for the whole document, for an element with a specific ID, or for elements matched by an XPATH expression. The XML document used to test is taken from Getting Started with XML Security : <?xml version="1.0"?> <PatientRecord> ... This is the Java code: import java.io.FileInputStream; import java.io.... However, it looks like the XPATH transform is not working. The digest generated with XPATH filter is exactly the same as that without it (i.e., the whole document)! Another reference: Programming With the Java XML Digital Signature API
Created by Dr. Xi on September 29, 2008 23:21:38    Last update: January 16, 2010 23:36:05
Create a startup script for inetd Copy /etc/init.d/skeleton to /etc/init.d/inetd . Change the top section of the script to read: PATH=/usr/sbin:/usr/bin:/sbin:/bin DESC="In... Now inetd can be stopped/started/restarted like this: sudo /etc/init.d/inetd stop sudo /etc/init.... Add links to rc*.d $ sudo update-rc.d inetd defaults Adding sy... If you no longer need to start inetd at boot up: $ sudo update-rc.d -f inetd remove update-r... This would remove the links from the start up sequence but leave /etc/init.d/inetd in place. Contents of /etc/init.d/skeleton : #! /bin/sh ### BEGIN INIT INFO # Provide...
Created by Dr. Xi on May 05, 2009 19:59:21    Last update: May 05, 2009 19:59:21
Delete a single file: >>> import os >>> file = 'myfile' >>> os.rem... Delete a directory and contents: >>> import shutil >>> dir(shutil) ['Error', ...
Created by Dr. Xi on November 23, 2008 05:31:00    Last update: November 26, 2008 21:41:25
CVS has two commands, cvs tag and cvs rtag for creating and manipulating labels. cvs tag uses the local file system to determine which revisions to associate with the label, while cvs rtag works directly on the repository. You can tag before checkout with the rtag command. If you checked out, had a successful build and want to create a baseline based on the checked out versions, you should use the tag command. # to add tag "my_tag" to module "my_module" on...
Created by Dr. Xi on September 25, 2008 02:58:27    Last update: October 14, 2008 22:49:32
This following code came from a JavaWorld tip, with some minor modifications. public class JWhich { /** * Retu...
Created by Dr. Xi on September 15, 2008 18:19:44    Last update: September 15, 2008 18:19:44
Some Ant built-in properties: Property Description basedir the absolute path of the project's basedir (as set with the basedir attribute of <project>). ant.file the absolute path of the buildfile. ant.version the version of Ant ant.project.name the name of the project that is currently executing. It is set in the name attribute of <project>. ant.java.version the JVM version Ant detected; currently it can hold the values "1.2", "1.3", "1.4" and "1.5". ant.home home directory of Ant In addition, Ant provides access to all system properties as if they had been defined using a <property> task. For example, ${os.name} expands to the name of the operating system.
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