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Java: resize image with high quality

Created by Fang on May 03, 2012 15:07:17 Last update: May 03, 2012 15:07:52

Scaling an image with default Java API loses quality (horribly!):


 
 public static BufferedImage resizeImage(Buffer...

The imgscalr library does the job beautifully. And its' very easy to do:

// import org.imgscalr.Scalr;
 
 
 
 public static...

To import the library in Maven:

<dependency>
 
 <groupId>org.imgscalr</groupId>
 
...

Reverse dns lookup in c

Created by magnum on January 30, 2012 18:13:52 Last update: January 30, 2012 18:13:52

There are two ways you cat get the name of a host from its ip address: getnameinfo and gethostbyaddr . The former is IPV6 compatible. Using getnameinfo :

#include <sys/types.h>
 
 #include <sys/socket.h>
...

Using gethostbyaddr :

#include <sys/types.h>
 
 #include <sys/socket.h>
...

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:...

Client socket bind example code in C

Created by magnum on September 27, 2011 21:51:05 Last update: September 28, 2011 18:02:49

Client socket usually does not call bind . But I've seen code that does and it was puzzling to me what bind does to a client socket. Therefore, this little test program. It retrieves a web url and displays info about the socket. You can optionally give a bind host name/ip and port and see what it does. Here are my test results:

$ ./client www.google.com
 
 Local addr: 172.16.0....

This is the code:

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

C client socket example code

Created by magnum on September 25, 2011 21:51:23 Last update: September 26, 2011 20:49:22

A simple socket client in C.

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

C gethostbyname example

Created by magnum on September 25, 2011 21:41:15 Last update: September 25, 2011 21:41:30

A simple C example for IP address lookup with gethostbyname .

#include <netdb.h>
 
 #include <stdio.h>
 
 #inclu...

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/

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