POJO to Map conversion

ApacheCommonExample.java

/**
 * Using Apache Common Bean Utils.
 */
import org.apache.commons.beanutils.BeanUtils;
import java.util.HashMap;

public class ApacheCommonExample throws IllegalAccessException, 
    InvocationTargetException, NoSuchMethodException {
	
	public HashMap<String,Object> convert(Person person) {
		HashMap<String,Object> hashMap = BeanUtils.describe(person);
		return hashMap;
	}
}

IntrospectorExample.java

/**
 * Using Introspector.
 */
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;

public class IntrospectorExample {
	
	public HashMap<String, Object> convert(Person person) 
			throws IntrospectionException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
		
  		HashMap<String, Object> hashMap = new HashMap<String, Object>();
  		BeanInfo beanInfo = Introspector.getBeanInfo(device.getClass());
  		
  		for(PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
  			Method reader = pd.getReadMethod();
  			
  			if(reader != null) {
  				hashMap.put(pd.getName(), reader.invoke(device));
  			}
  		}
		return hashMap;
	}
	
	public void mergeObject(Person source, Person target) 
					throws IntrospectionException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
		
		BeanInfo beanInfo;
		beanInfo = Introspector.getBeanInfo(target.getClass());
	
		// iterate all attributes
		for (PropertyDescriptor descriptor : beanInfo.getPropertyDescriptors()) {
			
			// only copy writable attributes
			if (descriptor.getWriteMethod() != null) {
				//Object oriVal = descriptor.getReadMethod().invoke(target);
				// only copy values where destination value is null
				//if (oriVal == null) {
				Object defaultValue = descriptor.getReadMethod().invoke(source);
				if(defaultValue != null)
					descriptor.getWriteMethod().invoke(target,defaultValue);
				//}
			}
		}
	}
}

JacksonExample.java

/**
 * Using Jackson Databind.
 */
import java.util.HashMap;
import com.fasterxml.jackson.databind.ObjectMapper;

public class JacksonExample {
	
	private static final ObjectMapper objectMapper = new ObjectMapper();
	
	@SuppressWarnings("unchecked")
	public HashMap<String, Object> convert(Person person) {
		
		HashMap<String, Object> hashMap = objectMapper.convertValue(person, HashMap.class);
		return hashMap;
	}
}

Person.java

// A POJO getter/setter
class  Person{
	String name;
	String age;
	
	//getter and setter
}