At a recent interview, a SpringBoot asked me 30 questions!

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From SSH to SpringMVC, with the development of Spring, it is easier to develop SpringBoot. SpringBoot has become a must for Java programmers.

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1. What is SpringBoot?

Spring Boot makes it easy to create standalone, production-level Spring-based applications that you can “run.” Most Spring Boot applications require minimal Spring configuration.

2.SpringBoot features?

Create a stand-alone Spring application
Embed directly into Tomcat, Jetty, or Undertow (no need to deploy WAR file)
Provide hardened “starter” dependencies to simplify build configurations
Automatically configure Spring and 3rd Party libraries whenever possible
Provides production-ready functionality, such as metrics, health checks, and externalized configuration
There is no code generation and no XML configuration required

3. How to quickly build a SpringBoot project?

Using the Web UI. http://start.spring.io
Use through Spring Tool Suite.
Used through IntelliJ IDEA.
Use the Spring Boot CLI.

4.SpringBoot boot class annotations? What annotations does it consist of?

@SpringBootApplication

@springBootConfiguration: The @Configuration annotation is combined to realize the function of the Configuration file.
@enableAutoConfiguration: Enable or disable the automatic configuration function.
@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class })
@ComponentScan:Spring component scanning

5. What is YAML?

YAML (/ˈjæməl/, ending like camel camel) is a readable format for data serialization. YAML references many other languages, including C, Python, and Perl. It’s more structured.

6. Which configuration file formats does SpringBoot support?

1.properties

java.xiaokaxiu.name = xiaoka
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2.yml

java:
  xiaokaxiu:
     name: xiaoka
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7.SpringBoot boot mode?

The main method
Command line java-jar way
mvn/gradle

8.SpringBoot needs a separate container to run?

No, Tomcat/Jetty is built in.

9.SpringBoot configuration path?

Command line arguments
Java: JNDI properties in comp/env
JVM System Properties
Operating system environment variables
Randomly generated attributes prefixed with random.* (they can be referenced when setting other attributes, such as ${random.long})
Properties or appliaction.yml file outside the application
Application. properties or appliaction.yml file packaged within the application
Annotated PropertySource via @propertysource
The default attribute

Tips: This list is sorted by priority, meaning that any property set in a high-priority property source overrides the same property set in a low-priority property source.

10. Application. The properties and application. Yml file location can be put on? Priority?

External, in the /config subdirectory relative to the application run directory.
External, in the directory where the application is running.
Built-in, in the config package.
Built-in, in the Classpath root.

The list is sorted by priority, with higher priority overwriting lower priority.

Of course we can specify the location of the file to load the configuration file ourselves.

Java - jar xiaoka. Jar - spring. Config. The location = / home/application. The ymlCopy the code

11.SpringBoot automatic configuration principle?

@ EnableAutoConfiguration automatic configuration (open) the annotations introduced AutoConfigurationImportSelector, methods of this class will scan all exist the meta-inf/spring. Factories jars.

12.SpringBoot hot deployment mode?

spring-boot-devtools
Spring Loaded
Jrebel
Template hot deployment

13.“bootstrap.yml“ 和“application.yml“?

Bootstrap. yml takes precedence over application.yml

14. How does SpringBoot change the port number?

In the yml:

server :
  port : 8888

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properties:

server.port = 8888
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Command 1:

Java-jar xiaoka.jar -- server.port=8888Copy the code

Command 2:

java - Dserver.port=8888 -jar xiaoka.jar
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15. How can I enable the SpringBoot feature?

Inherits the spring-boot-starter-parent project
Import the spring-boot-Dependencies project dependencies

16. How is SpringBoot compatible with Spring projects?

In the startup class add:

@ImportResource(locations = {“classpath:spring.xml”})

17.SpringBoot configuration monitoring?

<dependency> 
  <groupId>org.springframework.boot</groupId> 
  <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
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18. Which endpoint to visit for Bean assembly report information?

/ beans endpoint

19. Which endpoint is closed for application access?

/shutdown

This endpoint is disabled by default. If enabled, the following Settings are required.

 endpoints:
      shutdown:
        enabled: true
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Or the properties format is ok.

20. Which endpoint is visited to view published application information?

/info

21. How many combined annotations for the requested access?

@PatchMapping

@PostMapping

@GetMapping

@PutMapping

@DeleteMapping

22. Starter?

Understood as a combination of dependencies, the starter includes one or a set of functional-dependent dependencies, avoiding the hassle of having to rely on them and conflicting packages. Greatly improved the development efficiency.

There is a default value for the configuration, and if we configure it ourselves, the default value will be overridden.

23. Mybatis SpringBoot integration?

mybatis-spring-boot-starter

24. What are SpringProfiles?

Generally speaking, we go from development to production, through development (dev), test, and launch (PROD). We use different configurations at different times. Spring Profiles allows users to register beans against configuration files (dev, test, PROd, etc.). They allow us to choose what configuration to use and when.

25. Configuration files for different environments?

It can be application-{profile}.properties/yml, but the default is to launch the main configuration file application.properties. Generally our different environment configuration is as follows.

application.properties: Primary configuration file
application-dev.properties: Development environment configuration file
application-test.properties: Test environment configuration file
application.prop-properties: configuration file of the production environment

26. How do I activate an environment configuration?

Let’s say we activate the development environment.

Yml:

spring:
 profiles:
  active: dev
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