Simple Bean Mapper ---- Turn a Map<String, String> into an instance of any object an object. * key is the property name * value is the value associate to the property A key "class" must refer to the class name that must be instantiated

SimpleBeanMapper.java

package io.milkyway.spendtracker.servlet;

import java.beans.*;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.Map;

/**
 * Simple Bean Mapper
 *
 * Convert Map<String, String> to an object where the map :
 *  - key is the property name
 *  - value is the value associate to the property
 *
 *  The clazz of the object must be defined:
 *
 * Learn by example:
 * <code>
 *   class Cat
 *   {
 *     String name;
 *     boolean male;
 *   }
 *
 *   // test
 *   Map params = new Map();
 *   params.put("clazz", Cat.class.getName());
 *   params.put("name", "Bob");
 *   params.put("male", "true");
 *
 *   Cat cat = (Cat)BeanMapper.create(params);
 *   assert cat.name == "Bob";
 * </code>
 *
 * @author vicben01
 */
public class SimpleBeanMapper
{
  public static Object create(Map<String, String> params) throws IOException, ClassNotFoundException, IntrospectionException, InvocationTargetException, IllegalAccessException
  {
    if (params.get("clazz") == null)
      throw new NullPointerException("Bean is not defined, clazz == null");

    ClassLoader cl = Thread.currentThread().getContextClassLoader();
    Object instance = Beans.instantiate(cl, params.get("clazz"));
    BeanInfo bean = Introspector.getBeanInfo(instance.getClass());
    for (PropertyDescriptor property : bean.getPropertyDescriptors())
    {
      Method method = property.getWriteMethod();
      if (method != null)
      {
        String name = toVarName(method.getName());
        String value = params.get(name);
        Type type = method.getGenericParameterTypes()[0];
        String s = type.toString();
        if ("boolean".equals(s))
        {
          method.invoke(instance, new Boolean(value));
        }
        else if ("int".equals(s))
        {
          method.invoke(instance, new Integer(value));
        }
        else if(s.contains("float"))
        {
          method.invoke(instance, new Float(value));
        }
        else if(s.contains("long"))
        {
          method.invoke(instance, new Long(value.replace("L","")));
        }
        else if(s.contains("double"))
        {
          method.invoke(instance, new Double(value));
        }
        else if(s.contains("String"))
        {
          method.invoke(instance, value);
        }
        else
        {
          // do nothing
        }
      }
    }
    return instance;
  }

  private static String toVarName(String methodName)
  {
    String s = methodName.replace("set", "");
    return s.substring(0,1).toLowerCase() + s.substring(1);
  }
}