Everyday Utils

• Quick way to read contents from a file:

http://stackoverflow.com/questions/326390/how-to-create-a-java-string-from-the-contents-of-a-file
http://stackoverflow.com/questions/5529532/how-to-get-a-test-resource-file

Example java daemon code for Powershell interaction

Copy-pasted from: https://forums.oracle.com/forums/thread.jspa?messageID=10078419

public class Gobbler implements Runnable {
 
    private PrintStream out;
    private String message;
 
    private BufferedReader reader;
 
    public Gobbler(InputStream inputStream, PrintStream out) {
        this.reader = new BufferedReader(new InputStreamReader(inputStream));
               this.out = out;
        this.message = ( null != message ) ? message : "";
    }
 
    public void run() {
        String line;
 
        try {
            while (null != (line = this.reader.readLine())) {
                out.println(message + line);
            }
            this.reader.close();
        } catch (IOException e) {
            System.err.println("ERROR: " + e.getMessage());
        }
    }
}
 
 
public class PowerConsole {
 
    private ProcessBuilder pb;
    Process p;
    boolean closed = false;
    PrintWriter writer;
 
    PowerConsole(String[] commandList) {
        pb = new ProcessBuilder(commandList);
        try {
            p = pb.start();
        } catch (IOException ex) {
            throw new RuntimeException("Cannot execute PowerShell.exe", ex);
        }
        writer = new PrintWriter(new OutputStreamWriter(new BufferedOutputStream(p.getOutputStream())), true);
        Gobbler outGobbler = new Gobbler(p.getInputStream(), System.out);
        Gobbler errGobbler = new Gobbler(p.getErrorStream(), System.out);
        Thread outThread = new Thread(outGobbler);
        Thread errThread = new Thread(errGobbler);
        outThread.start();
        errThread.start();
    }
 
    public void execute(String command) {
        if (!closed) {
            writer.println(command);
            writer.flush();
        } else {
            throw new IllegalStateException("Power console has ben closed.");
        }
    }
 
    public void close() {
        try {
            execute("exit");
            p.waitFor();
        } catch (InterruptedException ex) {
        }
    }
 
    public static void main(String[] args) throws IOException, InterruptedException {
        /*   PowerConsole pc = new PowerConsole(new String[]{"/bin/bash"});
        
        PowerConsole pc = new PowerConsole(new String[]{"/bin/bash"});
        pc.execute("pwd");
        pc.execute("ls");
        pc.execute("cd /");
        pc.execute("ls -l");
        pc.execute("cd ~");
        pc.execute("find . -name 'test.*' -print");
        pc.close();
         */
        //      PowerConsole pc = new PowerConsole(new String[]{"cmd.exe"});
        PowerConsole pc = new PowerConsole(new String[]{"powershell.exe", "-NoExit", "-Command", "-"});
        System.out.println("========== Executing dir");
        pc.execute("dir"); 
        System.out.println("========== Executing cd\\");
        pc.execute("cd \\"); Thread.sleep(2000);
        System.out.println("========== Executing dir");
        pc.execute("dir"); Thread.sleep(2000);
        System.out.println("========== Executing cd \\temp");
        pc.execute("cd \\temp"); Thread.sleep(2000);
        System.out.println("========== Executing dir");
        pc.execute("dir"); Thread.sleep(2000);
        System.out.println("========== Executing cd \\bubba");
        pc.execute("cd \\bubba"); Thread.sleep(2000);
        System.out.println("========== Exiting .... bye.");
        pc.close();
    }
}

I tested this and there is still a little problem -look at the test below.
It seems that when thecommand
executed in the powershell prints only a one ot two lines,
powershell doesn't flush the output stream
.... but this rather problem of powershell, not the java code
I have not a clue how to force powershell to flush
it's output stream after each command.

C:\temp>java -jar PowerShell.jar
========== Executing dir
 
 
    Directory: Microsoft.PowerShell.Core\FileSystem::C:\temp
 
 
Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        2012-01-09     01:16       5290 PowerShell.jar
 
 
========== Executing cd\
========== Executing dir
 
 
    Directory: Microsoft.PowerShell.Core\FileSystem::C:\
 
 
Mode                LastWriteTime     Length Name
----                -------------     ------ ----
d----        2012-01-08     02:56            61587b977687a6e22fbe
d----        2011-12-14     03:19            Documents and Settings
d----        2011-12-15     00:05            oraclexe
d-r--        2012-01-08     03:44            Program Files
d----        2012-01-05     19:59            sqldeveloper
d----        2012-01-09     01:15            temp
d----        2012-01-09     01:13            WINDOWS
-a---        2011-12-14     03:12          0 AUTOEXEC.BAT
-a---        2011-12-14     03:12          0 CONFIG.SYS
 
 
========== Executing cd \temp
========== Executing dir
 
 
    Directory: Microsoft.PowerShell.Core\FileSystem::C:\temp
 
 
Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---        2012-01-09     01:16       5290 PowerShell.jar
 
 
========== Executing cd \bubba
Set-Location : Cannot find path 'C:\bubba' because it does not exist.
At line:1 char:3
+ cd  <<<< \bubba
========== Exiting .... bye.
 
C:\temp>

Simple way to read properties file in Java

Copy pasted from Link: http://www.mkyong.com/java/java-properties-file-examples/

package com.mkyong.common;
 
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;
 
public class App 
{
    public static void main( String[] args )
    {
     Properties prop = new Properties();
 
     try {
      //set the properties value
      prop.setProperty("database", "localhost");
      prop.setProperty("dbuser", "mkyong");
      prop.setProperty("dbpassword", "password");
 
      //save properties to project root folder
      prop.store(new FileOutputStream("config.properties"), null);
 
     } catch (IOException ex) {
      ex.printStackTrace();
        }
    }
}

package com.mkyong.common;
 
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;
 
public class App 
{
    public static void main( String[] args )
    {
     Properties prop = new Properties();
 
     try {
               //load a properties file
      prop.load(new FileInputStream("config.properties"));
 
               //get the property value and print it out
                System.out.println(prop.getProperty("database"));
      System.out.println(prop.getProperty("dbuser"));
      System.out.println(prop.getProperty("dbpassword"));
 
     } catch (IOException ex) {
      ex.printStackTrace();
        }
 
    }
}

package com.mkyong.common;
 
import java.io.FileInputStream;
import java.io.IOException;
import java.utilutil.Properties;
 
public class App 
{
    public static void main( String[] args )
    {
     Properties prop = new Properties();
 
     try {
               //load a properties file from class path, inside static method
      prop.load(App.class.getClassLoader().getResourceAsStream("config.properties");));
 
               //get the property value and print it out
                System.out.println(prop.getProperty("database"));
      System.out.println(prop.getProperty("dbuser"));
      System.out.println(prop.getProperty("dbpassword"));
 
     } catch (IOException ex) {
      ex.printStackTrace();
        }
 
    }
}

javax - Image IO SPI framework - supported readers / writers in registry

Base-64 implementation example

Copy-pasted from: http://www.wikihow.com/Encode-a-String-to-Base64-With-Java

public class Base64 {
 
    private static final String base64code = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
            + "abcdefghijklmnopqrstuvwxyz" + "0123456789" + "+/";
 
    private static final int splitLinesAt = 76;
 
    public static byte[] zeroPad(int length, byte[] bytes) {
        byte[] padded = new byte[length]; // initialized to zero by JVM
        System.arraycopy(bytes, 0, padded, 0, bytes.length);
        return padded;
    }
 
    public static String encode(String string) {
 
        String encoded = "";
        byte[] stringArray;
        try {
            stringArray = string.getBytes("UTF-8");  // use appropriate encoding string!
        } catch (Exception ignored) {
            stringArray = string.getBytes();  // use locale default rather than croak
        }
        // determine how many padding bytes to add to the output
        int paddingCount = (3 - (stringArray.length % 3)) % 3;
        // add any necessary padding to the input
        stringArray = zeroPad(stringArray.length + paddingCount, stringArray);
        // process 3 bytes at a time, churning out 4 output bytes
        // worry about CRLF insertions later
        for (int i = 0; i < stringArray.length; i += 3) {
            int j = ((stringArray[i] & 0xff) << 16) +
                ((stringArray[i + 1] & 0xff) << 8) + 
                (stringArray[i + 2] & 0xff);
            encoded = encoded + base64code.charAt((j >> 18) & 0x3f) +
                base64code.charAt((j >> 12) & 0x3f) +
                base64code.charAt((j >> 6) & 0x3f) +
                base64code.charAt(j & 0x3f);
        }
        // replace encoded padding nulls with "="
        return splitLines(encoded.substring(0, encoded.length() -
            paddingCount) + "==".substring(0, paddingCount));
 
    }
    public static String splitLines(String string) {
 
        String lines = "";
        for (int i = 0; i < string.length(); i += splitLinesAt) {
 
            lines += string.substring(i, Math.min(string.length(), i + splitLinesAt));
            lines += "\r\n";
 
        }
        return lines;
 
    }
    public static void main(String[] args) {
 
        for (int i = 0; i < args.length; i++) {
 
            System.err.println("encoding \"" + args[i] + "\"");
            System.out.println(encode(args[i]));
 
        }
 
    }
 
}

Java sample to do Https

Copied from blog: http://www.java-samples.com/showtutorial.php?tutorialid=1343

import java.io.*;
import java.net.*;
import java.security.Security.*;
import com.sun.net.ssl.*;
import com.sun.*; 
 public class sslpost {
       public static void main(String[] args){
        String cuki=new String();
try { 
System.setProperty("java.protocol.handler.pkgs", "com.sun.net.ssl.internal.www.protocol");
java.security.Security.addProvider(new com.sun.net.ssl.internal.ssl.Provider()); 
URL url = new URL("https://www.sunpage.com.sg/sso/login.asp"); 
 HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();
connection.setDoInput(true); 
connection.setDoOutput(true);

connection.setRequestMethod("POST"); 
connection.setFollowRedirects(true); 


String query = "UserID=" + URLEncoder.encode("williamalex@hotmail.com"); 
query += "&"; 
query += "password=" + URLEncoder.encode("password"); 
query += "&"; 
query += "UserChk=" + URLEncoder.encode("Bidder");
// This particular website I was working with, required that the referrel URL should be from this URL
// as specified the previousURL. If you do not have such requirement you may omit it.
query += "&"; 
query += "PreviousURL=" + URLEncoder.encode("https://www.sunpage.com.sg/sso/login.asp"); 


//connection.setRequestProperty("Accept-Language","it"); 
//connection.setRequestProperty("Accept", "application/cfm, image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, image/png, ///"); 
//connection.setRequestProperty("Accept-Encoding","gzip"); 


connection.setRequestProperty("Content-length",String.valueOf (query.length())); 
connection.setRequestProperty("Content-Type","application/x-www- form-urlencoded"); 
connection.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows 98; DigExt)"); 


// open up the output stream of the connection 
DataOutputStream output = new DataOutputStream( connection.getOutputStream() ); 


// write out the data 
int queryLength = query.length(); 
output.writeBytes( query ); 
//output.close();


System.out.println("Resp Code:"+connection.getResponseCode()); 
System.out.println("Resp Message:"+ connection.getResponseMessage()); 


// get ready to read the response from the cgi script 
DataInputStream input = new DataInputStream( connection.getInputStream() ); 


// read in each character until end-of-stream is detected 
for( int c = input.read(); c != -1; c = input.read() ) 
    System.out.print( (char)c ); 
input.close(); 
} 
catch(Exception e) 
{ 
System.out.println( "Something bad just happened." ); 
System.out.println( e ); 
e.printStackTrace(); 
} 
}
}

ThreadLocal - Usage and Explanation

Refer to a developer article : http://java.dzone.com/articles/java-thread-local-%E2%80%93-how-use

Read documentation on usage first in the above link. Then refer to the following sample code from the developer:

01.package com.veerasundar;

02. 

03.public class Context {

04. 

05.  private String transactionId = null;

06. 

07.        /* getters and setters here */

08. 

09.}

 

01.package com.veerasundar;

02. 

03./**

04. * this class acts as a container to our thread local variables.

05. * @author vsundar

06. *

07. */

08.public class MyThreadLocal {

09. 

10.  public static final ThreadLocal userThreadLocal = new ThreadLocal();

11. 

12.    public static void set(Context user) {

13.      userThreadLocal.set(user);

14.  }

15. 

16.   public static void unset() {

17.        userThreadLocal.remove();

18.   }

19. 

20.   public static Context get() {

21.       return userThreadLocal.get();

22.   }

23.}

 

01.package com.veerasundar;

02. 

03.public class ThreadLocalDemo extends Thread {

04. 

05.   public static void main(String args[]) {

06. 

07.        Thread threadOne = new ThreadLocalDemo();

08.       threadOne.start();

09. 

10.      Thread threadTwo = new ThreadLocalDemo();

11.       threadTwo.start();

12.  }

13. 

14.   @Override

15.   public void run() {

16.     // sample code to simulate transaction id

17.       Context context = new Context();

18.        context.setTransactionId(getName());

19. 

20.        // set the context object in thread local to access it somewhere else

21.       MyThreadLocal.set(context);

22. 

23.     /* note that we are not explicitly passing the transaction id */

24.        new BusinessService().businessMethod();

25.     MyThreadLocal.unset();

26. 

27.  }

28.}

 

01.package com.veerasundar;

02. 

03.public class BusinessService {

04. 

05.  public void businessMethod() {

06.      // get the context from thread local

07.        Context context = MyThreadLocal.get();

08.      System.out.println(context.getTransactionId());

09. }

10.}

 

 

Program to manipulate dependency map

Java Code :
-------------
package com.test.data;

import java.util.*;

// @author - Lakshman.
public class DependencyMap {
   
    private Map> dataMap = null;
   
    private Map valueMap = new HashMap();
   
    public DependencyMap(Map> argMap) {
        if (argMap != null) {
            dataMap = argMap;
        }
        else {
            dataMap = new HashMap>();
        }
    }
   
    public void createMap(String keyName, String keyVal) {       
        if (!dataMap.containsKey(keyName)) {
            return;
        }
       
        // Check if value is already set in values map.
        if (!valueMap.containsKey(keyName)) {
            valueMap.put(keyName, keyVal);           
        }
       
        // Get dependents.
        ArrayList valList = dataMap.get(keyName);
        if (valList == null) {
            return;
        }

        // Increment the value.
        int val = Integer.parseInt(keyVal);
        val++;
        String depVal = Integer.toString(val);

        // For each dependent, set - value + 1
        for (String depKey : valList) {
            if (!valueMap.containsKey(depKey)) {
                valueMap.put(depKey, new String(depVal));
            }
        }

        // For each dependent, recursively traverse.
        for (String depKey : valList) {
            createMap(depKey, depVal);
        }       
    }
   
    public void displayValueMap() {
        for (Map.Entry valEntry : valueMap.entrySet()) {
            System.out.println("Key = " + valEntry.getKey() + " :: Value = " + valEntry.getValue());
        }
    }
   
    public void displayDataMap() {
        if (dataMap == null) {
            return;
        }
       
        int count = 0;
        for (Map.Entry> dataMapEntry : dataMap.entrySet()) {
            count++;
            System.out.print("Element number - " + count);
            System.out.print (" - Key = " + dataMapEntry.getKey() + " :: Dependenct List = ");
            ArrayList valList = dataMapEntry.getValue();
            if (valList == null) {
                System.out.println();
                continue;
            }
            for (String val : valList) {
                System.out.print(val + " ; ");
            }
            System.out.println();
        }
    }
   
    private static HashMap> populateMap1() {
        HashMap> dataMap = new HashMap>();

        ArrayList valList = new ArrayList();
        valList.add("B");
        valList.add("C");
        valList.add("E");
        dataMap.put("A", valList);
       
        valList = new ArrayList();
        valList.add("C");
        valList.add("D");
        dataMap.put("B", valList);
       
        valList = new ArrayList();
        valList.add("E");
        dataMap.put("C", valList);

        dataMap.put("D", null);
        dataMap.put("E", null);       
       
        return dataMap;
    }
   
    public static void testcase1() {
        Map> dataMap = populateMap1();
        DependencyMap depMap = new DependencyMap(dataMap);
        depMap.displayDataMap();
        depMap.createMap("A", "1");
        depMap.displayValueMap();       
    }
   
    public static void main(String[] args) {
        testcase1();
    }
}

Output
--------
Element number - 1 - Key = D :: Dependenct List =
Element number - 2 - Key = E :: Dependenct List =
Element number - 3 - Key = A :: Dependenct List = B ; C ; E ;
Element number - 4 - Key = B :: Dependenct List = C ; D ;
Element number - 5 - Key = C :: Dependenct List = E ;

Key = D :: Value = 3
Key = E :: Value = 2
Key = A :: Value = 1
Key = B :: Value = 2
Key = C :: Value = 2

Servlets / JSP Tutorials

Servlets 3.0 / JSP 2.2 tutorials - 1: http://courses.coreservlets.com/Course-Materials/csajsp2.html

Unicode character APIs in Java

package com.struts1.tutorials.utils;

import java.util.ArrayList;
import java.util.List;

public class UnicodeCheck {
   
    public static int countUnicodeCharacters(char[] charArray) {
        if(charArray == null || charArray.length == 0)
            return 0;
        int numUnicodeChars = 0;
        for (int i = 0; i < charArray.length; i++) {
            if (Character.isLetter(charArray[i]) && !((charArray[i] >= 'a') && (charArray[i] <= 'z'))
                    && !((charArray[i] >= 'A') && (charArray[i] <= 'Z'))) {
                numUnicodeChars++;
                System.out.println("Unicode character = " + charArray[i]);
            }           
        }
        return numUnicodeChars;
    }
   

    // This does not work.
    public static int countUnicodeCharacters2(char[] charArray){
        if(charArray == null || charArray.length == 0)
            return 0;
        int numUnicodeChars = 0;
       
        System.out.println("********* Start Testing isLetter() API ************");
        for (int i = 0; i < charArray.length; i++) {
            if (Character.isLetter(charArray[i]) && !Character.isLowerCase(charArray[i]) && !Character.isUpperCase(charArray[i])) {
                numUnicodeChars++;
                System.out.println("isLetter() API : Character is unicode = " + charArray[i]);
                System.out.println("Character = " + charArray[i] +
                        " :: int value = " + i +
                        " :: getType = " + Character.getType(charArray[i]));
            }
        }
        System.out.println("********* End Testing isLetter() API ************");
        System.out.println("isLetter() API: Count of unicode characters = " + numUnicodeChars);
        return numUnicodeChars;
       
    }   
   
    public static void testcase1(char[] chArr) {
        System.out.println("Begin Testcase1()");
        for (char ch : chArr ) {
            int i = ch;
            System.out.println("Character = " + ch +
                                " :: int value = " + i +
                                " :: getType = " + Character.getType(ch));
            Character.UnicodeBlock block = Character.UnicodeBlock.of(ch);
            System.out.println("Unicode block = " + block);
            System.out.println("isUnicodeIdentifierPart = " + Character.isUnicodeIdentifierPart(ch));
            System.out.println("isUnicodeIdentifierStart = " + Character.isUnicodeIdentifierStart(ch));
        }
    }
   
    public static void main(String[] args) {
       
        List pwdList = new ArrayList();       
        pwdList.add("welcome1");
        pwdList.add("Enañol");
        pwdList.add("wel\u00f1");       
        pwdList.add("bargain12345");
        pwdList.add("....12345");
        pwdList.add("change1234");
        pwdList.add("cat12345");
               
        for (String pwd : pwdList) {
            char[] pwdChars = pwd.toCharArray();
            int count = countUnicodeCharacters(pwdChars);           
            System.out.println("Input password = " + pwd + " :: unicode chars count = " + count);
        }
    }
}


Output
=====
Input password = welcome1 :: unicode chars count = 0
Unicode character = ñ
Input password = Enañol :: unicode chars count = 1
Unicode character = ñ
Input password = welñ :: unicode chars count = 1
Input password = bargain12345 :: unicode chars count = 0
Input password = ....12345 :: unicode chars count = 0
Input password = change1234 :: unicode chars count = 0
Input password = cat12345 :: unicode chars count = 0