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Created by Dr. Xi on November 01, 2013 10:23:45    Last update: November 01, 2013 10:23:45
This example class generates and verifies RSA signature on a test file. import java.io.*; import java.security.*; im...
Created by Dr. Xi on November 11, 2011 10:05:22    Last update: November 11, 2011 10:12:01
This is an HTML image tag filter using Java regex. It takes a string, finds the img tags, replaces the src attribute with one provided by the filter, then adds a class name to the class attribute. import java.util.regex.*; import java.io.*; ... Test file: <div id="HTML snippet"> <img src="img/big/txt-m...
Created by alfa on July 15, 2011 13:25:45    Last update: July 15, 2011 13:25:45
Read the whole contents of a file into a String. It's better to read the whole file as bytes and convert to String than to read the file line by line and concatenate the lines. String getFileContents(String fileName) throws... Using java.nio : import java.io.FileInputStream; import java...
Created by freyo on May 23, 2011 14:30:18    Last update: May 23, 2011 14:31:08
There are two distinct ways to process XPath: with namespace and without namespace. The code is different depending on whether the parser is namespace aware. Code without namespace: import java.io.*; import javax.xml.parsers.*; ... code with namespace: import java.io.*; import java.util.Iterator; ... XML without namespace: <?xml version="1.0" encoding="UTF-8" standalone="n... XML with namespace: <?xml version="1.0" encoding="UTF-8" standalone="n... The same XPath expression works for both XML files when the parser is not namespace aware. When the parser is namespace aware, you have to adjust the XPath accordingly depending on whether the XML has namespace declarations: " /test-license/licensee/name/text() " works for the XML file without namespace, while " /p:test-license/p:licensee/p:name/text() " works for the XML file with namespace.
Created by alfa on April 06, 2011 12:48:44    Last update: April 06, 2011 12:48:44
package com.demo.io; import java.io.*; ...
Created by Dr. Xi on March 29, 2011 16:06:57    Last update: April 01, 2011 12:33:52
This utility class retrieves SSL certificates from the server and print them out to the stdout. The output can be saved to a file and imported to a Java keystore. This is useful in your test environment where the SSL certificate is self-signed. import java.io.InputStream; import java.io.Outp... Retrieve and import the a certificate: E:\test>java RetrieveSSLCert 192.168.69.144 8081 >...
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 Dr. Xi on March 30, 2011 13:43:05    Last update: March 30, 2011 13:45:27
Method 1 - use javap with verbose flag: $ javap HelloWorld -verbose | head Compiled fro... Method 2 - use a utility class: import java.io.*; import java.nio.ByteBuffer; ... According to the VM Spec , a Java class file has this structure: ClassFile { u4 magic; ...
Created by Dr. Xi on October 16, 2008 20:45:40    Last update: March 28, 2011 20:23:22
Java's built-in classes are way too complex/flexible for a simple protocol like HTTP. This is a wrapper to simplify HTTP GET and POST. import java.io.*; import java.net.*; imp... A simple test: import java.io.*; import java.util.*; ...
Created by voodoo on November 24, 2010 23:43:29    Last update: November 24, 2010 23:43:29
Two of the three PreparedStatement.setBinaryStream methods are not implemented as of version 9.0-801 of the PostgreSQL JDBC driver. Test program: import java.io.*; import java.sql.*; pub... Also note that setBinaryStream only works on a bytea column.
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