Using IndexedDB on Web Browser with Well Known Design Patterns — Only with Java by Mrs. Gwitany and Dr. Jackl

In the article “Using IndexedDB in Web Browser — All in Java” Mrs. Gwitany and Dr. Jackl told us how we could use Java with Elemental2 to build a simple prototype based on WebAPIs for IndexedDB. This time they’ll show us how to build the already shown code to be testable and maintainable with all the Design Patterns we already know from our server-side experiences with Java.

In the server-side Java world we use following patterns all the time, so we want to use them in the Web browser apps as well:

• Dependency Injection: we inject dependent object into a main object so that we could easily mock the injected object to be able to test the main object in a simple unit test. This is very useful especially if the dependent object uses e.g. database which can’t be booted very quickly.
• Service and Repository Pattern: we build services and those services access data repositories to be able to call the database operations.
• Rich Domain Model: we don’t want to build anemic domain model which contents only data, instead we also want to have some logics in it which is called rich domain model.
• Builder Pattern: we build our object step-by-step using correct sequence of…