ConfigPropertiesHelper

The ConfigPropertiesHelper class allows to simplify the implementation of the configuration API in Plugins configuration for named properties.

Overview of the API

The named configuration API has the following methods^[1]

Their default implementations do nothing

:

• The NamedConfiguration.getConfigurationPropertiesNames(String confName) method return the names of the properties for one named configuration. Return null by default
• The NamedConfiguration.getConfigurationPropertyType(String propertyName, String confName) method return the type of a property for a property name. Return null by default
• The NamedConfiguration.hasConfigurationProperty(String propertyName, String confName) method return true if a property with the specified name exists. Return false by default
• The NamedConfiguration.getConfigurationProperty(File dir, String propertyName, String confName) method return the value for a configuration property. Return null by default
• The NamedConfiguration.setConfigurationProperty(File dir, String propertyName, String confName, Object value) method sets the value for a configuration property. Does nothing by default

Using the Helper

The helper is used by:

• >Creating the default configuration (or the named configurations) in the Plugin configuration constrictor, then add propertirs for this or these configurations
• Then using the various methods of the ConfigPropertiesHelper to implement the named configuration API

Create a configuration

The ConfigPropertiesHelper instance will maintain the values of all properties. The first thing to do is to create the properties in the constructor of the Plugin configuration.

• To create the set of properties for the default configuration, use the ConfigPropertiesHelper.createDefaultConfiguration() method
• To create the set of properties for a named configuration, use the ConfigPropertiesHelper.createConfiguration(String configName) method

The result of these methods is a ConfigPropertiesHelper.ConfigSet instance.

Create properties for a configuration

To create a property for a configuration, use either:

• The ConfigPropertiesHelper.ConfigSet.addProperty(String name, Class type, Object defaultValue) method
• Or one of the addxxxProperty(String name) methods. In that case the default value will be set automatically by the class

Implement the API

• The NamedConfiguration.getConfigurationPropertiesNames(String confName) method can be implemented by using the ConfigPropertiesHelper.getConfigurationPropertiesNames(String confName) method
• The NamedConfiguration.getConfigurationPropertyType(String propertyName, String confName) method can be implemented by using the ConfigPropertiesHelper.getConfigurationPropertyType(String propertyName, String confName) method
• The NamedConfiguration.hasConfigurationProperty(String propertyName, String confName) method can be implemented by using the ConfigPropertiesHelper.hasConfigurationProperty(String propertyName, String confName) method
• The NamedConfiguration.getConfigurationProperty(File dir, String propertyName, String confName) method can be implemented by using the ConfigPropertiesHelper.getConfigurationProperty(File dir, String propertyName, String confName) method
• The NamedConfiguration.setConfigurationProperty(File dir, String propertyName, String confName, Object value) method can be implemented by using the ConfigPropertiesHelper.setConfigurationProperty(File dir, String propertyName, String confName, Object value) method

Example

In the following example, we have a Plugin configuration with two properties.

   public class OpenPNGImagePluginConfiguration implements Configuration {
      private static OpenPNGImagePluginConfiguration conf = null;
      private final ConfigPropertiesHelper helper = new ConfigPropertiesHelper();

      private OpenPNGImagePluginConfiguration() {
        ConfigPropertiesHelper.ConfigSet set = helper.createDefaultConfiguration();
        set.addIntProperty("maxWidth").setValue(1000);
        set.addBooleanProperty("limitWidth");
      }

      public static OpenPNGImagePluginConfiguration getInstance() {
        if (conf == null) {
          conf = new OpenPNGImagePluginConfiguration();
        }
        return conf;
      }

      @Override
      public Set<String> getConfigurationPropertiesNames(String confName) {
         return helper.getConfigurationPropertiesNames(confName);
      }

      @Override
      public boolean hasConfigurationProperty(String propertyName, String confName) {
        return helper.hasConfigurationProperty(propertyName, confName);
      }

      @Override
      public Object getConfigurationProperty(File dir, String propertyName, String confName) {
        return helper.getConfigurationProperty(dir, propertyName, confName);
      }

      @Override
      public Class getConfigurationPropertyType(String propertyName, String confName) {
        return helper.getConfigurationPropertyType(propertyName, confName);
      }

      @Override
      public void setConfigurationProperty(File dir, String propertyName, String confName, Object property) {
        helper.setConfigurationProperty(dir, propertyName, confName, property);
      }
   }