Spring-Boot-201 Flashcards
Do we require a parent tag in mvn while configuring the Boot ?
Yes with Mvn a tag is required
To which package all the boot dependncies fall on?
spring-boot-starters
How the Main class should be?
It should have annotated with @SpringBootApplication
Also provide the arg to SpringBootApplication.run in main method
What is mvnw
Maven wrapper, it is an automated building tool by spring boot
What goes in tag on pom.xml?
org.springframework.boot>
spring-boot-starter-parent>
What is a 12 factor app?
I. Codebase
One codebase tracked in revision control, many deploys
II. Dependencies
Explicitly declare and isolate dependencies
III. Config
Store config in the environment
IV. Backing services
Treat backing services as attached resources
V. Build, release, run
Strictly separate build and run stages
VI. Processes
Execute the app as one or more stateless processes
VII. Port binding
Export services via port binding
VIII. Concurrency
Scale out via the process model
IX. Disposability
Maximize robustness with fast startup and graceful shutdown
X. Dev/prod parity
Keep development, staging, and production as similar as possible
XI. Logs
Treat logs as event streams
XII. Admin processes
Run admin/management tasks as one-off processes
Can we have a yml prop also ?
Yes we can have yml also as prop
What is @SpringBootApplication composed of ?
@Confuguration, @ComponentScan, @EnableWebConfiguration
What does SprinBootaPPLICATION.RUN DOES
It gets to know which class is booting up
What is SpringApplicatioBuilder class?
Sometimes you require heirarchy or need multiple things to while booting up , this will help
new SpringApplicationBuilder(Main.cllass).child(otherconfig.class).run(args)
generally the weconfig goes to child part (like these)
How you can mute the logging info
new SpringApplicationBuilder(Main.class).logStraytupInfo(false).run(args);
How we can have profiles
With the same SpringApplicationBuilder use .profiles
How can we add listeners
Yes .listener and then impl the Interface like ApplicationEvent
How can we deliberately stop spring assuming the AutoConfiguration?
There are .operators like to SBApp class like : .web(WebApplicationType.NONE)
What @Order will do ?
If you want to execute the Main in certain order
How can we provide the prop files to Main
We can use Or @PropertySource, use default application.prop or applicaion.yml and place it in classpath
Yes Env variable can be used also
How can the property be accessed in a class?
@Value(“${prop}”)
How can be give the prop form cmd?
–prop=val Or -DProp=val
How to use mvnw
mvnw spring-boot:run -Dspring.config.name=val
What all is included in Spring web
Spring -web, webmvc, webflux & websocket
What are the names of he folder for static contents
/static, /public, /resources, /META-INF/resources
Can index.html server automatically?
Yes many of the java frameworks does that
What flexibility do we have with JSOn and XMl in Boot?
Yes the JSOn HttpMessageConverter is autoadded, and if the App has JSOnXMLExtension in CPath then XML converter will be auto added
Can we have more control about JSON to and fro processing?
Yes need to extend JsonSerializer Or JsonDesiriallizer and @JSonComponent.
By default Jackson is provided by Boot
Can we change the Jacksoon default date format?
Yes spring.jackson.date-format=SimpleDateFormat
Does Boot do the content negotiation by default?
Yes
What is the default error page locatin ?
/error
Where custom error page be created?
/src/main/resources/public/error : such as 55.html, 404.html, and the like
Whic anntoations to be used for handling errors?
@ControllerAdvice & @ExceptionHandler
How can custom error pages be registered?
By implementing ErrorPageRegistrar and declaring as Spring Bean
Say something about @RestController?
The @RestController offers @Controller also , and it used for handling request mappings, request input or exception handling
Say something about @RequestMapping ?
It is used for mapping the Http Methods , request params, headers and mediatypes. It can be used at class or method level
Explain @Autowired ?
The autowired can be ommitted , spring 5 and above auto does it, also it is used for injecting the constrtr dependency
Explain @PathVariable?
It is used for defining the variable which are coming into path , as /api/{id}, the name should match with the arg type
@RequestBody?
This is used to map JSON or XMl data to a Model class.
The Boot auto does it as it auto uses MappingJackson2HttpMessageConverter
ResponseEntity?
This return a full details API response with headers and the body which is converted to HttpMessageConvertors and wriiten to HTTP
@ResponseStatus?
This is used generally when null is returned with a status code.
State some of Principles of Spring FW?
Single Resposibility Principle(SIP) Open Closed Liskov-Substituion Interface Segregation Dependency Inversion
Explain SIP?
The SIP states that a module, class or fnction must have one resposibility & only one reason to change.
If we do not follow SIP, what will be the impact?
The classes will have cyclomatic complexity & poor testability
Explain OCP?
It states that class must be open for extension but closed for modification
In Boot, how does the Context Component Scan does automatically?
the package of @SpringBootApplication is taken into consideration by default
