Question

I am developing a Java web project and not applying Spring MVC, Spring web-flow to it (because it is quite simple). I have a small problem when attaching value from HTTP request to Java object. Is there any standalone library or utility support us to bind data from client request to a server object automatically (matched by property name) without using Spring? Assume that parameters in client request had already built to a map.
When I work with Grails (a web framework for Groovy), it has a very awesome way to fill data in request parameter to object by using: object.properties=parameters, but I do not know that in Java, do we have a similar mechanism to implement it?
Thank you so much.

Answer 1

Apache Commons might help with BeanUtilsBean. It has cool methods like getProperty() and setProperty(), which might help if you wanna try to code it by hand using reflection. There’s also the populate(Object bean, Map properties) method, which, i believe, is the closest to what you want.

Dozer is a java library specialized in mapping stuff from one structure to other. It might help.

This guy posted a similar question on coderanch and, after some discussion, he came up with the following:

public static <T extends Object> T setFromMap(Class<T> beanClazz, HashMap<String, String> propValues) throws Exception  
{  
    T bean = (T) beanClazz.newInstance();  
    Object obj = new Object();  
    PropertyDescriptor[] pdescriptors = null;  
    BeanInfo beanInfo = Introspector.getBeanInfo(beanClazz);  
    pdescriptors = beanInfo.getPropertyDescriptors();  
    for(int i=0; i<pdescriptors.length; i++)  
    {  
        String descriptorName = pdescriptors[i].getName();  
        if(!(descriptorName.equals("class")))  
        {  
            String propName = descriptorName;  
            String value = (String) propValues.get(propName);  
            if(value != null)  
            {  
                Object[] objArray = new Object[1];  
                objArray[0] = value;  
                Method writeMethod = pdescriptors[i].getWriteMethod();  
                writeMethod.invoke(bean, objArray);  
            }  
        }  
    }
    return bean;
}