PluginConfigConverter.java :  » Web-Framework » vraptor » org » vraptor » config » xml » Java Open Source

package org.vraptor.config.xml;

import java.util.HashMap;
import java.util.Map;

import org.vraptor.config.PluginConfig;
import org.vraptor.config.Property;

import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;

/**
 * A config factory component xml converter
 *
 * @author Guilherme Silveira
 * @author Rafael Steil
 */
public class PluginConfigConverter implements Converter {

  /**
   * Can it convert this class type?
   *
   * @see com.thoughtworks.xstream.converters.Converter#canConvert(java.lang.Class)
   */
  public boolean canConvert(Class clazz) {
    return clazz.equals(PluginConfig.class);
  }

  /**
   * Translates an object in the space to a xml string
   *
   * @see com.thoughtworks.xstream.converters.Converter#marshal(java.lang.Object,
   *      com.thoughtworks.xstream.io.HierarchicalStreamWriter,
   *      com.thoughtworks.xstream.converters.MarshallingContext)
   */
  public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {
    PluginConfig object = (PluginConfig) value;
    writer.setValue(object.getPluginClass().getName());
  }

  /**
   * Translates xml to an object
   */
  public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
    try {
      if (reader.hasMoreChildren()) {
        return unmarshallWithProperties(reader, context);
      } else {
        return unmarshallWithoutProperties(reader, context);
      }
    } catch (ClassNotFoundException e) {
      throw new ConversionException(e.getMessage(), e);
    }
  }

  private Object unmarshallWithoutProperties(HierarchicalStreamReader reader, UnmarshallingContext context)
      throws ClassNotFoundException {
    String value = reader.getValue();
    if (value == null) {
      throw new NullPointerException("The plugin element must have a value defined: the plugin type.");
    }
    return new PluginConfig(Class.forName(value.trim()), new HashMap<String,String>());
  }

  private Object unmarshallWithProperties(HierarchicalStreamReader reader, UnmarshallingContext context) throws ClassNotFoundException {
    String pluginClassName = reader.getAttribute("type");

    if (pluginClassName == null) {
      throw new NullPointerException("The plugin element must have a 'type' attribute");
    }

    Map<String,String> properties = new HashMap<String,String>();
    PluginConfig config = new PluginConfig(Class.forName(pluginClassName), properties);

    while (reader.hasMoreChildren()) {
      reader.moveDown();
      if (reader.getNodeName().equals("property")) {
        Property property = (Property) context.convertAnother(config, Property.class);
        properties.put(property.getName(), property.getValue());
      }
      reader.moveUp();
    }

    return config;
  }
}