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Java utility to convert String (byte array) to hex and reverse

Created by Dr. Xi on June 22, 2011 13:23:19 Last update: April 30, 2012 11:40:06

This is a utility to convert a byte array to hex string, and to convert a hex string back to the original. To convert a String to hex, you must call String.getBytes() first. The utility does not pretend to know your string encoding.

public class StringHexUtil {
 
     public static ...

This also works:

String binaryToHex(byte[] data) {
 
     StringBui...

JSP custom tags example with body

Created by Fang on January 28, 2012 13:24:09 Last update: January 28, 2012 13:31:22

This is a simple JSP custom tags library with tag body. Just like the JSF counterpart , it splits a string and repeats the body for each word, i.e., with this markup: <%@ taglib uri="http://custom.tag.com/demo" prefix... output:

<html>
 
 <body>
 
 	<p>Hello Tigger!</p>
 
 	<p>H...

With Maven, this is the directory structure:

./src
 
 ./src/main
 
 ./src/main/resources
 
 ./s...

There are three files to write: pom.xml : <project xmlns="http://maven.apache.org/POM/4.0.0"... src/main/java/tagdemo/IterateTag.java :

package tagdemo;
 
 
 
 import java.io.IOException...

src/main/resources/META-INF/demotag.tld :

<?xml version="1.0" encoding="UTF-8"?>
 
 
 
 <!DO...

Build with: mvn clean install To use it as a dependency in other Maven projects:

<dependency>
 
 	    <groupId>tag-demo</groupId>
 ...

Some notes on writing to a file owned by an app in SD card on Android

Created by lokf on January 13, 2012 14:10:42 Last update: January 13, 2012 14:10:42

For some reason I don't know writing to files in Android is very complicated and tedious. Here is some code for those who might need it. Apps should write in the SD in the directory /Android/data/package_name/files/ so that it is deleted with the app uninstall. package randomname; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.FileWriter; import java.io.IOException; import java.io.OutputStream; import java.io.OutputStreamWriter; import java.nio.ByteBuffer; import android.content.Context; import android.os.Environment; import android.util.Log; public class FileIOLibrary { String packageName; boolean mExternalStorageAvailable = false; boolean mExternalStorageWriteable = false; FileIOLibrary(String packageNamep) { this.packageName=packageNamep; } public boolean isExternalStorageAvailable() { updateExternalStorageState(); return mExternalStorageAvailable; } public boolean isExternalStorageWritable() { updateExternalStorageState(); return mExternalStorageWriteable; } /** * writes the current state of SD card to the corresponding variables */ void updateExternalStorageState() {...

Using tag handler, UI component and renderer with a JSF facelet taglib

Created by Fang on November 22, 2011 10:40:16 Last update: November 22, 2011 10:40:16

This is an example that uses tag handler, UI component and renderer together to support a custom taglib. The main purpose is to show how these components play together. The tag renders

<ui:param name="extra" value="el interpreted"/>
 
...

<h3>my:foreach</h3>
 
 <ul class="css class" extra...

These are the files: The tag handler ( src/main/java/com/example/ForeachTagHandler.java ):

package com.example;
 
 
 
 import java.util.Map;
...

The UI component ( src/main/java/com/example/UIForeach.java ):

package com.example;
 
 
 
 import java.io.IOExcep...

The renderer ( src/main/java/com/example/ForeachRenderer.java ):

package com.example;
 
 
 
 import java.io.IOExcep...

Faces config ( src/main/resources/META-INF/faces-config.xml ):

<?xml version="1.0" encoding="UTF-8"?>
 
 <faces-c...

Taglib config ( src/main/resources/META-INF/foreach.taglib.xml ):

<?xml version="1.0" encoding="UTF-8"?>
 
 <facelet...

JSF facelet taglib backed by a UI component

Created by Fang on November 08, 2011 20:55:00 Last update: November 21, 2011 18:19:44

In the simple taglib example , I used a tag handler class to implement a taglib. This is an example to implement a taglib with a UI component. The purpose is to use a custom tag to split a string and print each part in a separate paragraph, i.e., print john steve mike with custom tag <my:foreach> : <my:foreach var="who" value="john steve mike"> ... These are the files: pom.xml <project xmlns="http://maven.apache.org/POM/4.0.0"... src/main/java/com/example/UIForeash.java : package com.example; import java.io.IOExcep... src/main/resources/META-INF/faces-config.xml : <?xml version="1.0" encoding="UTF-8"?> <faces-c... src/main/resources/META-INF/foreach.taglib.xml : <?xml version="1.0" encoding="UTF-8"?> <facelet... How to use: Put the JAR file generated by the above project in the WEB-INF/lib folder of the web app. If the web app is a Maven project, just add the taglib project as a dependency:...

Java regex filter for HTML img tag

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...

C: get the IP address of a socket

Created by magnum on September 24, 2011 13:14:37 Last update: September 28, 2011 18:08:35

There are two sides to an IP socket: the local side and the remote side: The getpeername function retrieves the peer address of the specified socket.

#include <sys/socket.h>
 
 int getpeername(int soc...

Example:

struct sockaddr_in addr;
 
 socklen_t socklen = si...

The getsockname function retrieves the locally-bound name of the specified socket.

#include <sys/socket.h>
 
 int getsockname(int soc...

Example:

struct sockaddr_in addr;
 
 socklen_t socklen = si...

Dump binary Android xml files as plain text

Created by freyo on May 13, 2011 15:45:29 Last update: September 20, 2011 08:08:12

This is an Android app that dumps any binarized xml file as plain text - to the sdcard on the device or emulator. build.xml :

<?xml version="1.0" encoding="UTF-8"?>
 
 <project...

AndroidManifest.xml


 
 <?xml version="1.0" encoding="utf-8"?>
 
 <man...

res/layout/main.xml


 
 <?xml version="1.0" encoding="utf-8"?>
 
 <Lin...

res/values/strings.xml :


 
 <?xml version="1.0" encoding="utf-8"?>
 
 <res...

src/com/android/xmltool/DumpXml.java

package com.android.xmltool;
 
 
 
 import java.ut...

Screenshot Pre-built APK can be downloaded from: http://code.google.com/p/android-binxml-dump/

C: convert ip address to string and vice versa

Created by magnum on September 11, 2011 19:46:09 Last update: September 11, 2011 19:46:09

A pair of C functions convert between an Internet address and a string (ASCII):

#include <arpa/inet.h>
 
 /* 
 
  * Returns a poin...

However , these functions do not support IPv6. The new pair is:

#include <arpa/inet.h>
 
 /* Convert a Internet ad...

Examples:

#include <sys/socket.h>
 
 #include <netinet/in.h>...

C: read file into string (char*)

Created by voodoo on August 12, 2011 14:43:57 Last update: August 14, 2011 15:19:21

#include <stdio.h>
 
 #include <stdlib.h>
 
 
 
 i...

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