mvn archetype:create-from-project
Maps
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Sets
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Lists
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Queues
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Utilities
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HashMap
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HashSet
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PriorityQueue
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Collections
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Hashtable
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LinkedHashSet
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Vector
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Arrays
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TreeMap
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TreeSet
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LinkedList
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LinkedHashMap
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keytool -genseckey -alias mykey -keyalg AES -keysize 128 -storetype jceks -keystore keystore.jks -storepass password -keypass password
keytool -genkeypair -alias mykey -keyalg RSA -keysize 1024 -storetype jceks -validity 365 -keypass password -keystore ppkeystore.jck -storepass password -dname "cn=localhost, ou=Verisign, o=MyComp Inc, l=Foster City, st=California, c=US"
As mentioned above a public key can be given to user to encrypt data. A public key can be considered as open padlock which can be used to lock something but cannot be used to unlock.keytool -export -alias mykey -storetype jceks -keystore ppkeystore.jck -storepass password -file public.crt
This certificate is of standard X.509 that is the Public key Infrastructure for 509. This standard is used to generate certificates by Certificate Authority(CA).
The certificate contains Issuer, Validity, Public Key Info. The certificate itself is digitally signed by the private key of the issuing authority like Thawte, Verisign and the signature is also embedded in the certificate in the Signature Algorithm section. This type of certificates that are issued by a third party are generally used for webapplications that need to run on HTTPS/SSL port.keytool -importcert -alias mykey -file public.crt -keystore pptruststore.jck -keypass password -storepass password
Owner: CN=localhost, OU=Verisign, O=MyComp Inc, L=Foster City, ST=California, C=US Issuer: CN=localhost, OU=Verisign, O=MyComp Inc, L=Foster City, ST=California, C=US Serial number: 5218562e Valid from: Sat Aug 24 12:13:58 IST 2013 until: Sun Aug 24 12:13:58 IST 2014 Certificate fingerprints: MD5: FC:CA:65:5D:25:0D:4A:4F:7E:4F:B9:A0:31:6B:42:16 SHA1: C2:FD:48:18:E5:EF:9D:B4:3E:3F:34:3E:D3:24:B1:42:A4:EE:F3:52 Signature algorithm name: SHA1withRSA Version: 3 Trust this certificate? [no]: yes Certificate was added to keystore
<dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.8</version> </dependency>
import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.PrivateKey; import java.security.PublicKey; import javax.crypto.Cipher; import org.apache.commons.codec.binary.Base64; public class AssymmetricKey { public static void main(String[] args) throws Exception { KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA"); keyPairGenerator.initialize(1024); KeyPair keyPair = keyPairGenerator.generateKeyPair(); PrivateKey privateKey = keyPair.getPrivate(); PublicKey publicKey = keyPair.getPublic(); String dataToBeEncrypted = "MyHome"; Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); String encryptedData =Base64.encodeBase64String(cipher.doFinal(dataToBeEncrypted.getBytes())); System.out.println("Encrypted Data: " + encryptedData); Cipher dipher = Cipher.getInstance("RSA"); dipher.init(Cipher.DECRYPT_MODE, privateKey); System.out.println(new String(dipher.doFinal(Base64.decodeBase64(encryptedData)))); } }
<dependency> <groupId>commons-codec</groupId> <artifactId>commons-codec</artifactId> <version>1.8</version> </dependency>
import java.io.UnsupportedEncodingException; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.KeyGenerator; import javax.crypto.NoSuchPaddingException; import javax.crypto.SecretKey; import javax.crypto.spec.SecretKeySpec; import org.apache.commons.codec.binary.Base64; public class SymmetricKey { public static void main(String[] args) throws Exception { //Generate Symmetric key KeyGenerator generator = KeyGenerator.getInstance("AES"); generator.init(128); SecretKey key = generator.generateKey(); byte[] symmetricKey =key.getEncoded(); System.out.println("key : "+symmetricKey); //Encrypt Data String encryptedData = encryptWithAESKey("asd", symmetricKey); System.out.println("Encrypted Data : " + encryptedData); //Decrypt Data System.out.println("Decrypted Data : " +decryptWithAESKey(encryptedData, symmetricKey)); } public static String encryptWithAESKey(String data, byte[] key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException { SecretKey secKey = new SecretKeySpec(key,"AES"); Cipher cipher = Cipher.getInstance("AES"); cipher.init(Cipher.ENCRYPT_MODE, secKey); byte[] newData = cipher.doFinal(data.getBytes()); return Base64.encodeBase64String(newData); } public static String decryptWithAESKey(String inputData, byte[] key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException { Cipher cipher = Cipher.getInstance("AES"); SecretKey secKey = new SecretKeySpec(key, "AES"); cipher.init(Cipher.DECRYPT_MODE, secKey); byte[] newData = cipher.doFinal(Base64.decodeBase64(inputData.getBytes())); return new String(newData); } }In the above example KeyGenerator is instantiated with AES algorithm. Every Java Implementation needs to implement one of below given algorithm.
For analogy we can consider public key as a padlock as shown above and private key as the key to the padlock. A padlock can be used to lock a box without the key and than the key can be used to open the padlock opening the box.
public class Chef extends Thread{ String plate; public void run(){ plate="Ratatouille"; } }
public class John{ public static void main(String[] args) { Chef chef = new Chef (); chef .start(); System.out.println("Main consuming :"+chef .plate); } }
Main consuming :null
public class Chef extends Thread { String plate; public void run() { synchronized (this) { try { System.out.println("Chef: Prepairing Ratatouille..."); Thread.sleep(2000); plate = "Ratatouille"; System.out.println("Chef: Ratatouille prepaired, notify John"); this.notify(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }
public class John { public static void main(String[] args) throws InterruptedException { Chef chef = new Chef(); chef.start(); synchronized (chef) { if (chef.plate == null) { System.out.println("John : Plate is empty, wait.."); chef.wait(); } System.out.println("John consuming :" + chef.plate); } } }
John : Plate is empty, wait.. Chef: Prepairing Ratatouille... Chef: Ratatouille prepaired, notify John John consuming :RatatouilleHere now John checks if plate is emty or not. John calls wait() on Chef instance variable and waits, that is it releases lock on Chef instance. Chef class now can enter the synchronized block. It calls the notify() method on the same chef object and tells john to go ahead.
Object.wait()
Object.notify()
public class Bank { int balance = 100; public void deposit(int amount) { this.balance = amount; System.out.println(Thread.currentThread().getName()+" Deposit:" + balance); } public void withdraw(int amount) throws Exception{ if (balance >= amount) { System.out.println(Thread.currentThread().getName()+" Withdrawing:" + balance); Thread.sleep(5000); this.balance =this.balance- amount; System.out.println(Thread.currentThread().getName()+" Withdrawn" + balance); } else { System.out.println(Thread.currentThread().getName()+" Withdraw: entered amount : " + amount + " more than balance:" + balance); } } }
public class Withdrawer extends Thread { Bank bank; public Withdrawer(Bank bank) { this.bank = bank; } public void run(){ try { bank.withdraw(100); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
import java.util.TreeMap; public class TestBank { public static void main(String[] args) { Bank bank = new Bank(); Withdrawer withdrawer = new Withdrawer(bank); Withdrawer withdrawer2 = new Withdrawer(bank); withdrawer.start(); withdrawer2.start(); } }
Thread-0 Withdrawing:100 Thread-1 Withdrawing:100 Thread-0 Withdrawn0 Thread-1 Withdrawn-100
public class Bank { int balance = 100; public void deposit(int amount) { this.balance = amount; System.out.println(Thread.currentThread().getName()+" Deposit:" + balance); } public synchronized void withdraw(int amount) throws Exception{ if (balance >= amount) { System.out.println(Thread.currentThread().getName()+" Withdrawing:" + balance); Thread.sleep(5000); this.balance =this.balance- amount; System.out.println(Thread.currentThread().getName()+" Withdrawn" + balance); } else { System.out.println(Thread.currentThread().getName()+" Withdraw: entered amount : " + amount + " more than balance:" + balance); } } }
Thread-0 Withdrawing:100 Thread-0 Withdrawn0 Thread-1 Withdraw: entered amount : 100 more than balance:0
package com.hunaid.thread; public class MyThread extends Thread{ public void run(){ System.out.println("MyThread run called"); for(int i=0;i<=5;i++){ System.out.println(i); } } }
package com.hunaid.thread; public class ThreadTest { public static void main(String args[]){ MyThread myThread = new MyThread(); myThread.start(); System.out.println("In Main after starting MyThread"); } }Here we have created a instance of MyThread class and called the method start() on it.
MyThread run called 0 1 2 3 4 5 In Main after starting MyThreadThe text 'In Main after starting MyThread' could be printed anywhere between 0 to 5. That is because while the thread MyThread is running JVM could decide to give the main thread that is main() method the execution slot.
| Host | |
| SOAP | REST |
| JAX-WS | JAX-RS |
| Spring-ws | Spring-MVC-REST |
| Client | |
| SOAP | REST |
| JAX-WS(wsimport) | Google REST APP |
| SOAP UI | Apache REST |