What is sc4j

sc4j provides an easy and fast possibility to read properties (e.g. from a properties file). The default implementation reads the configuration from a properties file, but it is very easy to swap the implementation against your own one. For this purpose, only the 'ConfigurationInterface' provider must be implemented.

Simple Example

If you would like to read the following property file:

#my configuration file

# this is the mail host to send the mails
email.host=smtp@bartels.de

# the port to from the mail host
email.port=20

#authentication 
email.account.user.name=bartels
email.account.user.pwd=bartels
```
	
Normally we would implement a class to wrap the access to the property file,
Like the following example:

```java

public class MyConfiguration {
   public static final String EMAIL_HOST = "email.host";
   public static final String EMAIL_PORT = "email.port";
   public static final String EMAIL_ACCOUNT_USER_NAME = "email.account.user.name";
   public static final String EAMIL_ACCOUNT_USER_PWD  = "email.account.user.pwd";
   
   public static final String EMAIL_HOST_DEFAULT_VALUE = "foobar@bartels.de";
   
   private Properties properties;
   
   public MyConfiguration(final String propertyFilePath) {
        // some magic to load the file and the properties;
   }
   
   public String getEmailHost() {
      String host = properties.get(EMAIL_HOST);
      return host == null ? EMAIL_HOST_DEFAULT_VALUE : host;
   }
   
   public int getEmailPort() {
      String  sPort = properties.get(EMAIL_PORT);
      if(sPort != null) {
         int port = Integer.parseInt(sPort);
         return port;
      }
      throw new IllegalStateException("invalid argument");
   }
   
   // getter methods for the other properties
   [...]
}

```

and then we would use the class like this:

```java
  [...]
  
  public void configureMailSystem() {
     // load the properties
     MyConfiguration config = new MyConfiguration("MyPropertiesFile.properties");  
     
     // do something with the loaded properties
     config.getEmailHost();
  }
```

With the sc4j lib we only need to define an interface with the properties we would like to read:

```java

@PropertyFile("MyPropertiesFile.properties")
public interface MyConfiguration {

   /**
   *
   * @return returns the email.host property if the property is null the default value will returned
   */
   @DefaultValue("foobar@bartels.de")
   String emailHost();

   int emailPort();
   
   /**
   * with the PropertyPath annotions you're able to specify a different property key to read the property
   * @return returns the email.account.user.name property
   */
   @PropertyPath("email.account.user.name")
   String userName();

   @PropertyPath("email.account.user.pwd")
   String userPwd();
}

```

how to use the interface:

```java
   public class MyFancyClass {
      // load the properties
      private static final MyConfiguration CONFIG = ConfigurationFactory.create(MyConfiguration.class);
   
      public void configureMailSystem() {
         // do something with the loaded properties
         CONFIG.emailHost();
      }
   }
```