Recent Notes

XmlPullParser example code

Created by freyo on April 18, 2011 14:14:29 Last update: April 18, 2011 14:15:48

For XML resources, Android returns an XmlPullParser reference. I tried the RSSReader example from xmlpull.org , it failed both on the Android emulator and with xpp3-1.1.4c . This is an example for XmlPullParser usage. Since the XmlPullParser is event based, a callback mechanism works better. Java code:

import java.io.*;
 
 import java.net.*;
 
 import ...

The XML file used:

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

Android write to file (internal storage)

Created by freyo on April 15, 2011 09:00:54 Last update: April 15, 2011 09:00:54

Sample code for writing to a file in the internal storage. There are three steps: Open the file with Context.openFileOutput , which returns java.io.FileOutputStream . Write to the file. Close the file.

import java.io.*;
 
 import android.content.Contex...

The second parameter to openFileOutput is the operating mode. Available values are: Context.MODE_PRIVATE Context.MODE_APPEND Context.MODE_WORLD_READABLE Context.MODE_WORLD_WRITEABLE The file is saved in /data/data/<package_name>/files .

Java screen capture: current application window

Created by alfa on April 08, 2011 12:33:08 Last update: April 08, 2011 12:33:08

This example captures the screen of the current Java application window, instead of the full screen.

import java.io.*;
 
 import java.awt.*;
 
 import ...

Java screen capture example code

Created by alfa on April 08, 2011 11:05:24 Last update: April 08, 2011 11:05:24

Key points: Use java.awt.Robot to capture a screen region as java.awt.image.BufferedImage . Use javax.imageio.ImageIO to write image out to a file.

import java.awt.AWTException;
 
 import java.awt.R...

Java: write XML to file with transformer

Created by nogeek on April 07, 2011 21:30:54 Last update: April 07, 2011 21:30:54

This is the opposite of parsing. You can use javax.xml.transform.Transformer to output a DOM tree to a file.

import java.io.*;
 
 import javax.xml.parsers.Docu...

Java parse xml string example

Created by nogeek on April 07, 2011 20:54:17 Last update: April 07, 2011 20:54:17

Use javax.xml.parsers.DocumentBuilder to parse xml. DocumentBuilder.parse() takes: java.io.File org.xml.sax.InputSource java.io.InputStream java.lang.String as a URI to an XML document Example code:

import java.io.*;
 
 import javax.xml.parsers.Docu...

RSA key/certificate file formats: pkcs#7, pkcs#8, pkcs#12, pem

Created by freyo on April 07, 2011 15:29:01 Last update: April 07, 2011 15:29:01

Format Name Description PKCS #7 Cryptographic Message Syntax Standard A PKCS #7 file can be used to store certificates, which is a SignedData structure without data (just the certificates). The file name extension is usually .p7b , .p7c PKCS #8 Private-Key Information Syntax Standard. Used to carry private certificate keypairs (encrypted or unencrypted). PKCS #12 Personal Information Exchange Syntax Standard. Defines a file format commonly used to store private keys with accompanying public key certificates, protected with a password-based symmetric key. It is the successor to PFX from Microsoft. DER Distinguished Encoding Rules A binary format for keys or certificates. It is a message transfer syntax specified by the ITU in X.690. PEM Privacy Enhanced Mail Base64 encoded DER certificates or keys, with additional header...

Java file as url

Created by alfa on April 06, 2011 13:23:40 Last update: April 06, 2011 13:23:40

A file can be read as URL with the java.net package. You must provide absolute path after the URI scheme name file:// .

package com.demo.io;
 
 
 
 import java.io.*;
 
 i...

Java read file as byte array

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.*;
 
 
...

Ξ Notes

Android xml resource example