What
is spring-boot-starter-parent in Spring-Boot pom.xml file?
We have seen that
spring-boot application pom.xml has parent declaration as shown in the below
pom.xml file. Why do we need that?
|
As we know, in general,
parent pom declarations allows us to manage following things for multiple child
projects.
- Configuration:
It allows us to maintain consistancy in terms of java version and other
related properties accross all sub projects.
- Depedency
Management:
This will control all versions of the dependencies to avoid dependency
version conflicts.
- Default
Plugin Configuration
Let’s explore real-time spring boot interview questions.
1. What is Spring Boot?
A) Spring Boot is a sub-project of Spring’s open source
organization. It is a one-stop solution for Spring components. It mainly
simplifies the difficulty of using Spring. It saves a lot of configuration and
provides various launchers, so developers can get started quickly.
2. Why use Spring Boot?
A) Spring Boot has many advantages, such as:
·
Operate independently
·
Simplified configuration
·
Automatic configuration
·
No code generation and XML configuration
·
Application monitoring
·
Easy to get started
Spring Boot has so many advantages.
3) What are the advantages of Spring Boot?
A) The advantages of Spring Boot are:
·
Reduce development, testing time and effort.
·
Using JavaConfig helps avoid using XML.
·
Avoid a lot of Maven import and various version conflicts.
·
Provide advice development methods.
·
Start development quickly by providing default values.
·
There is no separate web server required. This means you no
longer need to start Tomcat, Glassfish or anything else.
·
Less configuration is required because there is no web.xml
file. Just add the class annotated with @Configuration and add the method
annotated with @Bean. Spring will automatically load the object and manage it
as before. You can even add @Autowired to the bean method to have Spring
automatically load the required dependencies.
·
Environment-based configuration Using these properties, you can
pass the environment you are using to the application: -Dspring.profiles.active
= {enviornment}. After loading the main application properties file,
Spring will load the subsequent application properties file in (application{environment}
.properties).
4) What are the core configuration files for Spring
Boot? What is the difference between them?
A) The core configuration files for Spring Boot are the
application and bootstrap configuration files.
The application configuration file is easy to understand and is
primarily used for automated configuration of Spring Boot projects.
The bootstrap configuration file has the following application
scenarios.
·
When using Spring Cloud Config to configure the hub, you need to
add the configuration properties of the connection to the configuration center
in the bootstrap configuration file to load the configuration information of
the external configuration center.
·
Some fixed attributes that cannot be overridden;
·
Some encryption/decryption scenarios;
5) What is JavaConfig?
A) Spring JavaConfig is a product of the Spring community that
provides pure Java methods for configuring Spring IoC containers. So it
helps to avoid using XML configuration. The advantages of using JavaConfig
are:
·
Object-oriented configuration. Since the configuration is
defined as a class in JavaConfig, users can take advantage of the
object-oriented features in Java. A configuration class can inherit from
another, override its @Bean method, and so on.
·
Reduce or eliminate XML configuration. The benefits of
externalization configuration based on the principle of dependency injection
have been proven. However, many developers don’t want to switch back and
forth between XML and Java. JavaConfig provides developers with a pure
Java way to configure Spring containers similar to the XML configuration
concept. From a technical point of view, it is possible to configure the
container using only the JavaConfig configuration class, but in fact many
people think that it is ideal to mix JavaConfig and XML.
·
Type safety and refactoring friendly. JavaConfig provides a
type-safe way to configure the Spring container. Thanks to Java 5.0
support for generics, it is now possible to retrieve beans by type rather than
by name, without any cast or string-based lookups.
6) What are the formats of Spring Boot configuration
files? What is the difference between them?
A) .properties and .yml, the main difference between them is the
writing format.
1).properties
App.user.name = javastack
2).yml
App: user: name: javastack
In addition, .yml format does not support
@PropertySourceannotations import
configuration.
7) Which is the core annotation of Spring Boot? Which annotations
is it mainly composed of?
A) The annotation above the startup class is
@SpringBootApplication, which is also a core annotation for Spring Boot. The
main combination contains the following three annotations:
@SpringBootConfiguration: Combines the @Configuration annotation
to implement the configuration file.
@EnableAutoConfiguration: Turns on automatic configuration. You
can also turn off an automatic configuration option, such as turning off data
source auto-configuration: @SpringBootApplication(exclude = {
DataSourceAutoConfiguration.class }).
@ComponentScan: Spring component scan.
8) What are the ways to enable Spring Boot features?
1) Inherit the spring-boot-starter-parent project
2) Import spring-boot-dependencies project dependencies
9) Does Spring Boot require a separate container to run?
A) It is not necessary, and a container such as Tomcat/ Jetty is
built in.
10) What are the ways to run Spring Boot?
1) Packing with commands or putting them into a container
2) Run with the Maven/Gradle plugin
3) directly execute the main method to run
11) What is Swagger? Did you implement it with Spring Boot?
A) Swagger is widely used for visual APIs, using the Swagger UI
to provide an online sandbox for front-end developers. Swagger is a tool
for generating visual representations of RESTful web services, specifications
and full framework implementations.
It enables documents to be updated at the same speed as the
server. When properly defined by Swagger, consumers can use a minimal
amount of implementation logic to understand and interact with remote
services. Therefore, Swagger eliminates the guesswork when calling the
service.
12) What is Spring Profiles?
A) Spring Profiles allows users to register beans based on
configuration files (dev, test, prod, etc.). Therefore, when the
application is running in development, only certain beans can be loaded, while
in PRODUCTION, some other beans can be loaded.
Suppose our requirement is that the Swagger document is only for
the QA environment and all other documents are disabled. This can be done
using a configuration file. Spring Boot makes it easy to use configuration
files.
13) What is Spring Batch?
A) Spring Boot Batch provides reusable functions that are
important when working with large numbers of records, including
logging/tracking, transaction management, job processing statistics, job
restarts, skipping, and resource management.
It also provides more advanced technical services and features
that enable extremely high volume and high-performance batch operations through
optimization and partitioning techniques. Simple and complex high-volume
batch jobs can use the framework to process a large amount of information in a
highly scalable manner.
14) What is a FreeMarker template?
A) FreeMarker is a Java-based templating engine that initially
focused on dynamic web page generation using the MVC software
architecture. The main advantage of using Freemarker is the complete
separation of the presentation and business layers.
Programmers can handle application code, and designers can
handle html page design. Finally, you can combine these with freemarker to
give the final output page.
15) How to implement exception handling using Spring Boot?
Spring provides a very useful way to handle exceptions using
ControllerAdvice. We handle all exceptions thrown by the controller class
by implementing a ControlerAdvice class.
Spring Framework
16) Which starter maven dependencies have you used?
A) Used some of the following dependencies
spring-boot-starter-activemqspring-boot-starter-securityspring-boot-starter-web
This helps increase fewer dependencies and reduces version
conflicts.
17) What is a CSRF attack?
A) CSRF stands for cross-site request forgery. This is an attack
that forces the end user to perform unwanted operations on the currently
authenticated web application.
CSRF attacks are specifically targeted at state change requests,
not data theft because an attacker cannot view responses to forged requests.
18) What is WebSockets?
A) WebSocket is a computer communication protocol that provides
a full duplex communication channel over a single TCP connection.
·
WebSocket is bidirectional – you can use a WebSocket client or
server to initiate a message.
·
WebSocket is full-duplex – client and server communication are
independent of each other.
·
Single TCP connection – The initial connection uses HTTP and
then upgrades this connection to a socket-based connection. Then this
single connection is used for all future communications
·
Light – WebSocket message data exchange is much lighter than
http.
19) What is AOP?
A) In the software development process, the function of crossing
multiple points of the application is called a crossover problem. These
cross-cutting issues are different from the main business logic of the
application. Therefore, separating these crosscutting concerns from
business logic is where Aspect Oriented Programming (AOP) is.
20) What is Apache Kafka?
Apache Kafka is a distributed publish-subscribe messaging
system. It is an extensible, fault-tolerant publish-subscribe messaging
system that enables us to build distributed applications. This is an
Apache top-level project. Kafka is suitable for offline and online
messaging.
Microservices
21) How do we monitor all Spring Boot microservices?
A) Spring Boot provides monitor endpoints to monitor the metrics
of individual microservices. These endpoints are useful for getting
information about the application, such as whether they are up and running, and
whether their components, such as databases, are working.
However, one of the main drawbacks or difficulties with using
monitors is that we have to open the application’s knowledge points separately
to understand their status or health. Imagine a microservice involving 50
applications, and the administrator will have to hit the execution terminals of
all 50 applications.
To help us deal with this situation, we will use
https://github.com/codecentric/spring-boot-admin
Open source project. Built on top of the Spring Boot
Actuator, it provides a Web UI that allows us to visualize the metrics of
multiple applications.
22) What is the Spring Boot automatic configuration principle?
A) Note @EnableAutoConfiguration, @Configuration, @ConditionalOnClass
is the core of automatic configuration, first it must be a configuration file,
and then according to the class path to have this class to automatically
configure.
23) What is the directory structure of Spring Boot?
Cn +- javastack +- MyApplication.java | +- customer | +-
Customer.java | +- CustomerController.java | +- CustomerService.java | +-
CustomerRepository.java | +- order +- Order.java +- OrderController. Java +-
OrderService.java +- OrderRepository.java
This directory structure is the mainstream and recommended
practice, and the @SpringBootApplication annotation is added to the main entry
class to enable Spring Boot’s capabilities, such as automatic configuration,
component scanning, and so on.
24) How do you understand Starters in Spring Boot?
A) Starters can be understood as a launcher, which contains a
set of dependencies that can be integrated into the application. You can
integrate Spring and other technologies in one place without having to find
sample code and dependencies everywhere. If you want to use Spring JPA to
access the database, just add the spring-boot-starter-data-jpa launcher
dependency to use.
Starters contain dependencies that are needed in many projects.
They run quickly and continuously and are a set of supported management
transitive dependencies.
25) How do I run some specific code when Spring Boot starts?
A) You can implement the interface ApplicationRunner or
CommandLineRunner. These two interfaces are implemented in the same way. They
only provide a run method.
Spring Microservices
26) What are the ways in which Spring Boot can read configurations?
A) Spring Boot can bind variables via @PropertySource, @Value,
@Environment, @ConfigurationProperties.
27) What log framework does Spring Boot support? Which is the
recommended and default log framework?
A) Spring Boot supports Java Util Logging, Log4j2, and Lockback
as the logging framework. If you use the Starters launcher, Spring Boot will
use Logback as the default logging framework.
28) What are the ways in which SpringBoot implements hot deployment?
A) There are two main ways:
·
Spring Loaded
·
Spring-boot-devtools
29) How do you understand the Spring Boot configuration load order?
A) In Spring Boot, there are several ways to load a
configuration.
1.
Properties file;
2.
YAML files;
3.
System environment variables;
4.
Command line parameters;
and many more……
30) How does Spring Boot define multiple sets of different
environment configurations?
A) Provide multiple sets of configuration files, such as:
Applcation.properties application-dev.properties
application-test.properties application-prod.properties
Specify a specific configuration file at runtime.
31) Can Spring Boot be compatible with older Spring projects? How do
I do this?
A) Compatible, use
@ImportResourceannotations to import
old Spring project configuration file.
32) What are the methods to protect Spring Boot applications?
·
Use HTTPS in production
·
Check your dependencies with Snyk
·
Upgrade to the latest version
·
Enable CSRF protection
·
Use content security policies to prevent XSS attacks
33) What are the new features of Spring Boot 2.X? What is the
difference with 1.X?
·
Configuration change
·
JDK version upgrade
·
Third-party class library upgrade
·
Responsive Spring programming support
·
HTTP/2 support
·
Configuration property binding
·
More improvements and enhancements…
No comments:
Post a Comment