A little example shows how to develop services with interfaces and implementations without dependencies to Spring Framework or Google Guice:

The Maven pom.xml

	4.0.0
	de.schaeftlein.dev
	jsr330-sample
jar
	jsr330-sample
	0.0.1-SNAPSHOT
	Sample App with Spring 3.0 RC 2 and JSR330

		3.0.0.RC2
	

	
		
			org.springframework
			spring-core
			${springVersion}
		
		
			org.springframework
			spring-beans
			${springVersion}
		
		
			org.springframework
			spring-context
			${springVersion}
		
		
			org.springframework
			spring-asm
			${springVersion}
		
		
			org.springframework
			spring-expression
			${springVersion}
		
		
			junit
			junit
			4.7
			test
		
		
			javax.inject
			javax.inject
			1
		
	
	
		jsr330-sample
		src/main/java
		${basedir}/src/test/java

		
		
			
				src/main/resources
				
					**/.svn
					**/.svn/**
					**/_svn
					_svn
					**/_svn/**
				
			
		
		
			
				src/test/resources
				
					**/.svn
					**/.svn/**
					**/_svn
					_svn
					**/_svn/**
				
			
		


				org.apache.maven.plugins
				maven-compiler-plugin
				
					1.6
					1.6
				
			

				org.apache.maven.plugins
				maven-eclipse-plugin
				
					true
					true
					
						_svn
						.svn
					
				
			

				org.apache.maven.plugins
				maven-jar-plugin
				
					
						
							true
						
					
				
			
			

				org.apache.maven.plugins
				maven-source-plugin
				
					
						attach-sources
verify
						
							jar
						
					
				
			
		
	

a simple encode/decode interface

package de.schaeftlein.dev.spring;

public interface Encryption
{
  String encode(String value);
  String decode(String value);
}

a simple implementation for Encryption

package de.schaeftlein.dev.spring;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

import javax.inject.Named;

@Named // service name is the name of the class
public class URLEncoderEncyrption implements Encryption
{

  @Override
  public String decode(String value)
  {
    try
    {
      return URLDecoder.decode(value, "UTF-8");
    }
    catch (UnsupportedEncodingException e)
    {
      return null; // never happen
    }
  }

  @Override
  public String encode(String value)
  {
    try
    {
      return URLEncoder.encode(value, "UTF-8");
    }
    catch (UnsupportedEncodingException e)
    {
      return null; // never happen
    }
  }

}

a more secure implementation for Encryption

package de.schaeftlein.dev.spring;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.inject.Named;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import com.sun.org.apache.xml.internal.security.utils.Base64;

@Named("secure") // named service bean
public class Base64Encyption implements Encryption
{
  private sun.misc.BASE64Encoder base64encoder;
  private SecretKey key;

  public Base64Encyption()
  {
    try
    {
      DESKeySpec keySpec = new DESKeySpec("Your secret Key phrase".getBytes("UTF8"));
      SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
      key = keyFactory.generateSecret(keySpec);
      base64encoder = new BASE64Encoder();
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
  }

  @Override
  public String decode(String input)
  {
    try
    {
      Cipher cipher = Cipher.getInstance("DES"); // cipher is not thread safe
      cipher.init(Cipher.DECRYPT_MODE, key);
      byte[] bOut = cipher.doFinal(Base64.decode(input.getBytes("UTF-8")));
      return new String(bOut, "UTF-8");
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return null;
  }

  @Override
  public String encode(String plainTextPassword)
  {
    try
    {
      byte[] cleartext = plainTextPassword.getBytes("UTF8");

      Cipher cipher = Cipher.getInstance("DES"); // cipher is not thread safe
      cipher.init(Cipher.ENCRYPT_MODE, key);
      return base64encoder.encode(cipher.doFinal(cleartext));
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return null;
  }

}

a small interface for a service

package de.schaeftlein.dev.spring;

public interface SecureUtil
{
  void compareEncryption(String input);
}

a implementation for our service

package de.schaeftlein.dev.spring;

import javax.inject.Inject;
import javax.inject.Named;

@Named("SecureUtil")
public class SecureUtilImpl implements SecureUtil
{
  @Inject // automatically set by DI framework
  @Named("secure") // get the namend bean
  private Encryption secureEncryption;

  @Inject // automatically set by DI framework
  @Named("URLEncoderEncyrption") // get the bean by its classname
  private Encryption unsecureEncryption;

  public void compareEncryption(String input){

    String encodedSecure = secureEncryption.encode(input);
    System.out.println("Secure encoded: "+encodedSecure);
    String encodeUnsecure = unsecureEncryption.encode(input);
    System.out.println("Unsecure encoded: "+encodeUnsecure);
    System.out.println("Secure decoded: "+secureEncryption.decode(encodedSecure));
    System.out.println("Unsecure decoded: "+unsecureEncryption.decode(encodeUnsecure));
  }
}

finally a main class for testing

package de.schaeftlein.dev.spring;

import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main
{

  /**
   * main method
   */
  public static void main(String[] args)
  {
    ApplicationContext ctx = new AnnotationConfigApplicationContext(Main.class.getPackage().getName()); // new way to get Application context without applicationContext.xml available
    SecureUtil util = ctx.getBean("SecureUtil", SecureUtil.class); // get bean with new generics method
    util.compareEncryption("an sample input string 1234567890");
  }

}

output of our Main class

19.11.2009 18:56:03 org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@c1b531: startup date [Thu Nov 19 18:56:03 CET 2009]; root of context hierarchy
19.11.2009 18:56:03 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor 
INFO: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
19.11.2009 18:56:03 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@a83b8a: defining beans [org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,secure,SecureUtil,URLEncoderEncyrption]; root of factory hierarchy
Secure encoded: QDQvd4uK14YNUQ4uoqhqsZEMDDxUqJAMyisvZr2wsA2GyMC5tSEIiw==
Unsecure encoded: an+sample+input+string+1234567890
Secure decoded: an sample input string 1234567890
Unsecure decoded: an sample input string 1234567890