Mapping Dozer vs MapStruct
In multi-tier applications there is often a need for mapping between two data models. In this article you can read about comparing two mapping libraries:
- Dozer (http://dozer.sourceforge.net/) - popular library, where mapping is configured by XML files
- MapStruct (http://mapstruct.org/) - library, which is used for example in JHipster generator
The most common use case is coping data from entity objects to DTO objects usually used in service REST/SOAP.
| Dozer | MapStruct | |
| Description | Mapping rules are defined in XML files, which are then loaded during application runtime. Dozer is using reflection mechanism for mapping. | Mapping rules are defined in Java files, mostly in annotations. Based on this rules MapStruct generates Java classes, which are then used for mapping. |
| Speed | Dozer uses reflection mechanism for mapping, which means it is slower than MapStruct. In example (link) it is mapped 1 000 000 objects. On my notebook it takes about 16 seconds. | MapStruct invoke methods of classes, which were generated before compilation. Thanks to that it works faster than Dozer. In example (link) it is mapped 1 000 000 objects. On my notebook it takes about 3 seconds. |
| MapStruct is about 500% faster than Dozer. | ||
| Security | When you make a mistake in XML that contains mapping rules you will know about it only during invoking mapping (runtime error). | When you make a mistake in property name, you will know about it during compilation. Thanks that application will be more reliable. |
| Immutable objects | Dozer can access private properties (by reflection). It makes possible to map immutable objects which haven’t setters. It requires that immutable object has a constructor without parameters and in mapping files you should add attribute is-accessible="true" to destination fields. | Unfortunately MapStruct hasn’t ability to map immutable objects. There is an open issue about that. |
| Debugging | Mapping rules are defined mostly in XML files. During application runtime that files are loaded. Thus debugging mapping process is difficult – you have to set breakpoints in Dozer classes. | You can set breakpoint in classes, which was generated during compilation. Thanks that you can easily determine which classes are used for mapping and debug them. |
| Popularity (as at the date 23.03.2016) | Creation date: 04.06.2005 Stackoverflow: 1610 posts Github: https://github.com/DozerMapper/dozer Last release date: 22.04.2014 | Creation date: 22.05.2012 Stackoverflow: 108 posts Github: https://github.com/mapstruct/mapstruct Last release date: 16.03.2016 |
| Additional advantages |
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I've prepared a small application, which does the same mapping using Dozer and MapStruct libraries. You can easily notice the difference in speed.