Spring framework comes with many modules that makes java developers' life easier. Spring Boot works like a charm. It has never been easier to write java applications.
This document is created to show how simple a JPA application can be written.
A JPA application starts with creating JPA entity and DAO classes. JPA entity classes can be generated using a tool that comes with any Java IDE. In spring data, DAO classes are called as Repository classes. A repository or DAO object is used to save,update,delete or retrieve entity objects. Traditionally DAO classes were created using Base Dao classes. Base classes were saving us from writing boiler plates for save, update or delete methods. But when it comes to retrieval methods, boiler plate codes were unavoidable. Good news is that, spring data comes with a good idea. Query methods save us from boiler plates. See [1] for more details.
Entity class is a standard JPA entity.
An example service class is given below. By use of Autowired annotation, repository object is easily acquired. No XML configuration is needed. Method is marked as transactional for declarative transaction management. Component annotation is necessary to make this class spring managed.
Spring boot application is started like this. EnableJpaRepositories is needed if repositories other than Jpa is also used. EntityScan is needed if entity classes are in a separate jar file.
Compare this code with your legacy application. Thank you spring framework :) For complete code listing see github link at [2]. For the second part of this document see [3].
1. Spring Data - Query methods
2. Github - essync
3. Spring Boot Elasticsearch Application
This document is created to show how simple a JPA application can be written.
A JPA application starts with creating JPA entity and DAO classes. JPA entity classes can be generated using a tool that comes with any Java IDE. In spring data, DAO classes are called as Repository classes. A repository or DAO object is used to save,update,delete or retrieve entity objects. Traditionally DAO classes were created using Base Dao classes. Base classes were saving us from writing boiler plates for save, update or delete methods. But when it comes to retrieval methods, boiler plate codes were unavoidable. Good news is that, spring data comes with a good idea. Query methods save us from boiler plates. See [1] for more details.
Entity class is a standard JPA entity.
An example service class is given below. By use of Autowired annotation, repository object is easily acquired. No XML configuration is needed. Method is marked as transactional for declarative transaction management. Component annotation is necessary to make this class spring managed.
Spring boot application is started like this. EnableJpaRepositories is needed if repositories other than Jpa is also used. EntityScan is needed if entity classes are in a separate jar file.
Compare this code with your legacy application. Thank you spring framework :) For complete code listing see github link at [2]. For the second part of this document see [3].
1. Spring Data - Query methods
2. Github - essync
3. Spring Boot Elasticsearch Application
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