如何检查Spring-boot或相关框架的所有合格bean

Question

I want to know how to discover all qualifying beans that should be implemented when using some component together Spring.

For example, when using JPA and Spring Boot we need beans as like as sessionFactory and dataSource (Any more? I don't know, see It?).

Is there any official place where I can check the pre requisite list of beans?

Answer 1

I've made many searches through the official schemas and I couldn't find a pattern for bean dependencies.

After some time I've come into some steps that helped me and maybe help others. I'm answering this also because there are a lot of material related to Beans in XML files and in a Maven project, but if you try to create a XML free project, things become more rare when using Spring.

Notice: in deep Spring doesn't cares if the bean is an annotation or inside a XML. I preferred these configurations as a personal choice.

Some project details:

• Gradle (project configurations are in application.properties file)

• Java 8

• Bean class(es) for src and for test. Note: You can use extends among them.

• In case of doubt, https://start.spring.io/ an awesome way to create from nothing a spring project with your dependencies. Gradle format dependencies usually can be found at maven repository nearby the maven format.

Resolution:

• Create a unit test (eg JUnit) to just test your layer. For example mine was persistence layer.

• Be careful to add each framework(that is going to be loaded by Spring) at once. Dealing with many unconfigured frameworks at same time would lead to caos since may be hard to figure out from where the Bean class should come from.

• When the test fails look at his bottom of your console. Some exception will be thrown saying that a Bean with some name is missing. This are the guys you need.

• Create a method typed with @Bean inside a class typed with @Configuration. This method must returns variable/object type complained in the exception message. Additional annotations maybe be required, for example, @EnableTransactionManagement for JPA beans.

Bonus:

Spring is deeply connected to IoC (dependency injection) and containers. Take a look at this contents because when you see that you realizes why to use Beans.