CODEWITHSUNDEEP
javajavabeans
slim
slim

Reputation: 41271

Canonicalizing Java bean property names

I have a bunch of third-party Java classes that use different property names for what are essentially the same property:

public class Foo {
   public String getReferenceID();
   public void setReferenceID(String id);
   public String getFilename();
   public void setFilename(String fileName);
}

public class Bar {
   public String getRefID();
   public void setRefID(String id);
   public String getFileName();
   public void setFileName(String fileName);
}

I'd like to be able to address these in a canonicalized form, so that I can treat them polymorphically, and so that I can do stuff with Apache BeanUtils like:

PropertyUtils.copyProperties(object1,object2);

Clearly it would be trivial to write an Adapter for each class ...

public class CanonicalizedBar implements CanonicalizedBazBean {
    public String getReferenceID() {
        return this.delegate.getRefID();
    }
    // etc.
}

But I wonder is there something out there more generalized and dynamic? Something that would take a one-to-many map of property name equivalences, and a delegate class, and produce the Adapter?

Upvotes: 9

Views: 1056

Answers (5)

eaglestorm
eaglestorm

Reputation: 1202

I haven't done much with it but you may be able to use Aspect Oriented Programming to do this.

What you should be able to do I think is add a method to each of the classes that internally calls the real method. See this article about half way down it talks about mixins.

AspectJ is probably the most popular implementation.

Upvotes: 1

Asaf
Asaf

Reputation: 6510

Although, I personally have never used it. I noticed that a project called orika is noted as having the best performance and the ability to automatically understand many such mappings. At any rate it also supports custom mappings and uses generated code to implicitly define the adapters.

You can also define a custom mapper, that is if you know how to canonize the member names you can use that knowledge to build a mapping that is true for all your objects. for instance:

DefaultFieldMapper myDefaultMapper = new DefaultFieldMapper() {
   public String suggestMapping(String propertyName, Type<?> fromPropertyType) {
      // split word according to camel case (apache commons lang)
      String[] words= StringUtils.splitByCharacterTypeCamelCase(propertyName);
      if(words[0].length() > 6) {
         // trim first camel-cased word of propery name to 3 letters
         words[0]= words[0].substring(0,2);
         return StringUtils.join(words);
      } else {
         // remains unchanged
         return propertyName;
      }   
   }
}

mapperFactory.registerDefaultFieldMapper(myDefaultMapper );

Upvotes: 2

nidomiro
nidomiro

Reputation: 830

maybe something like that:

public class CanonicalizedBar implements CanonicalizedBazBean {
public String getReferenceID() {
    Method m = this.delegate.getClass().getDeclaredMethod("getReferenceID");
    if(m == null)
        m = this.delegate.getClass().getDeclaredMethod("getRefID");
    ...
    return m.invoke();
}
// etc.
}

Upvotes: 2

Puspendu Banerjee
Puspendu Banerjee

Reputation: 2651

  1. First Option is Dozer.

  2. Second option is Smooks Framework with a tweak. It will be beneficial to use Smook's Graphical mapper.

  3. Another option would be XStream with custom Mapper.

Upvotes: 4

JB Nizet
JB Nizet

Reputation: 692181

I've never used it, but I think you're looking for Dozer:

Dozer is a Java Bean to Java Bean mapper that recursively copies data from one object to another. Typically, these Java Beans will be of different complex types.

Dozer supports simple property mapping, complex type mapping, bi-directional mapping, implicit-explicit mapping, as well as recursive mapping. This includes mapping collection attributes that also need mapping at the element level.

Dozer not only supports mapping between attribute names, but also automatically converting between types. Most conversion scenarios are supported out of the box, but Dozer also allows you to specify custom conversions via XML.

Upvotes: 6

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