Normally, the jar package that starts springboot can be read through –spring.profiles.active=dev. application-dev.yml configuration file information, start it
This startup is very strange. Entering this startup environment parameter still has no effect,
It’s so scary, it’s so unexpected!
Instead of reading application-dev.yml, it reads the default application.yml file
However, using the startup parameters of jvm: java -jar -Dspring.profiles.active=dev, it can be started, which proves that the dev configuration file is valid
Entrance of application Class discovery:
public static void main(String[] args){ SpringApplication.run(Application.class,args); }
When calling the run method, no args were passed in!
Read the source code and find out, pass in the startup parameters, then parse the incoming parameters, and set the properties
Note:
Be careful, the startup code needs to pass in the startup parameters!!! Only then can the startup parameters be entered to take effect at startup
SpringBoot allows us to have multiple configuration files, and then dynamically load the corresponding configuration file based on conditions when the project starts.
There are now three configurations, one default configuration file (application.properties: because it is the name specified by SpringBoot, so it is called the default configuration file), and two specified environment configuration files (application-prod.properties and application-dev .properties: related to the corresponding environment, so they are called designated environment configuration files)
application-dev.properties
Simulation development configuration information
person.name=ZhangSan person.age=18
application-prod.properties
Simulate production configuration information
person.name=LiSi person.age=19
application.properties
Just specify the port number of a service and the configuration file that needs to be loaded when the project starts, SpringBoot will Automatically match application-{spring.profiles.active}.properties, and then find the application-dev.properties configuration file
server.port=8080 spring.profiles.active=dev #我们可以指定SpringBoot在启动时加载那个对应的配置文件
Create a case Person class and let it When instantiated, read information from the configuration file, read the rule: person.{property name}, create a new instance of Person, and add it to the IOC container.
Create a get request and return our Person instance. Let’s see if the perosn attribute value can load the corresponding configuration file according to the spring.profiles.active attribute we specified in the application.properties configuration file. Person Is the value in the instance the expected value?
@ConfigurationProperties(prefix = "person") //初始化的时候从配置文件中读取person.{属性名}的信息赋值给当前对象 @Data public class Person { private String name; private Integer age; } @Configuration //配置文件信息,将Person实例注入到IOC容器中 public class MyConfig { @Bean public Person person() { return new Person(); } }
@RestController //Create a get request and return our Person instance. Let’s see if the perosn attribute value can be specified in the spring configuration file according to the application.properties configuration file. The .profiles.active attribute loads the corresponding configuration file. Is the value in the Person instance the expected value?
@RequestMapping("/user") public class PersonController { @Autowired private Person person; @GetMapping public Person getPerson() { return person; } }
When the project is run, visit http://localhost:8080/user and the result is returned:
{"name":"ZhangSan","age":18}
Change the value of spring.profiles.active in application.properties to prod and request access to http: //localhost:8080/user, return result:
{"name":"LiSi","age":19}
In addition, if we have already installed the project Packaged into a jar, you can specify the value of spring.profiles.active by assigning values to parameters from the command line when starting the SpringBoot project
java -jar .\web-02-0.0.1-SNAPSHOT.jar --spring.profiles.active=dev
Another more practical one is that SpringBoot loads application.properties and The path and priority of application.yaml (seen from the official SpringBoot documentation: https://docs.spring.io/spring-boot/docs/current/reference/html/features.html#features.external-config. application-json), loading priority:
application.properties and application.yaml
under /config/{first-level subdirectory} under the directory where the jar package is locatedapplication.properties and application.yaml under /config in the directory where the jar package is located
application.properties and application.properties under the directory where the jar package is located application.yaml
application.properties and application.yaml in /config under classpath
application.properties and application.yaml under classpath
The scenario is: Our project has been running for a long time, and the configuration file needs to be modified due to emergencies. But we don’t dare to modify the old configuration files at will. At this time, we can put our new coordination files in a high-priority place.
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