1 ,@ spring boot application
This is the core annotation of Spring Boot, which is used in the main class of Spring Boot to identify that this is an application of Spring Boot and to open various capabilities of Spring Boot.
In fact, this annotation is a combination of three annotations: @SpringBootConfiguration, @EnableAutoConfiguration and @ComponentScan, which can also be used instead of @SpringBootApplication annotation.
2. @ Enable automatic configuration
Allow Spring Boot to automatically configure comments. When this annotation is enabled, Spring Boot can configure Spring Bean according to the packages or classes in the current classpath.
For example, if there is a JAR package Mybatis in the current classpath, the MybatisAutoConfiguration annotation can configure each Spring Bean of Mybatis according to relevant parameters.
3. @ Configuration
This is a comment added by Spring 3.0 to replace the applicationContext.xml configuration file. Everything that can be done in this configuration file can be registered through the class to which this comment belongs.
4 、@SpringBootConfiguration
This annotation is a variant of the @Configuration annotation, which is only used to decorate the configuration of Spring Boot, and can also be beneficial to the subsequent expansion of Spring Boot.
5. @ component scanning
This is a comment added by Spring 3. 1, which is used to replace the component-scan configuration in the configuration file, start component scanning, that is, automatically scan the @Component comment under the package path, and register the bean instance into the context.
For the first five annotations, please refer to the Detailed Explanation of Three Core Annotations of Spring Boot in this article.
6. @ Conditional
This is a new note in Spring 4.0, which is used to identify a Spring Bean or configuration file, and the configuration will not be opened until the specified conditions are met.
7 、@ ConditionalOnBean
Combines the @Conditional annotation to open the configuration only when the specified Bean exists in the container.
8 、@ ConditionalOnMissingBean
In contrast to the @Conditional Bean annotation, combining the @ conditional annotation opens the configuration when there is no specified Bean in the container.
9 、@ ConditionalOnClass
Combines the @Conditional annotation to open the configuration only if there is a specified class in the container.
10 ,@ conditionalomissingclass
Contrary to the @ConditionalOnMissingClass annotation, the combination @ Conditional annotation opens the configuration when there is no specified class in the container.
1 1 ,@ ConditionalOnWebApplication
Combination @ conditional comments, the current project type is WEB project open configuration.
There are currently three types of projects.
Enumeration type {
}
12 ,@ ConditionalOnNotWebApplication
The combination of @Conditional annotation, contrary to @ConditionalOnWebApplication annotation, only opens the configuration when the current project type is not a WEB project.
13 ,@ conditional property
Combines the @Conditional annotation to open the layout only when the specified attribute has the specified value.
14 ,@ conditional expression
Combines the @Conditional annotation and opens the configuration when the SpEL expression is true.
15 ,@ ConditionalOnJava
When the running Java JVM is within the specified version range, open the configuration with the @Conditional annotation.
16 ,@ conditional resource
Combines the @Conditional annotation to open the configuration only when there are specified resources under the classpath.
17 ,@ ConditionalOnJndi
When the specified JNDI exists, combine the @Conditional annotation to open the configuration.
18 ,@ conditionalonludplatform
Combined with @Conditional annotation, the configuration will only be opened when the specified cloud platform is activated.
19 ,@ conditionalonsingcandidate
Combined with the @Conditional annotation, open the configuration when the specified class has only one Bean in the container, or there are multiple beans at the same time, but it is the first choice.
20. @ Configure Properties
Used to load additional configurations (such as. Property file), which can be used on @Configuration annotation classes or @Bean annotation methods.
2 1 、@EnableConfigurationProperties
Generally, it should be used with the @ConfigurationProperties annotation to support the @ConfigurationProperties annotation configuration Bean.
22. @ After automatic configuration
Used for automatic configuration class, indicating that the automatic configuration class needs to be configured after another specified automatic configuration class.
For example, the automatic configuration class of Mybatis needs to be after the automatic configuration class of the data source.
23. Before @ Automatic Configuration
This is contrary to the use of the @AutoConfigureAfter annotation, indicating that the autoconfiguration class needs to be configured before another specified autoconfiguration class.
24. @ Import
This is a new annotation in Spring 3.0, which is used to import one or more classes decorated by the @Configuration annotation. This annotation is widely used in Spring Boot.
25 、@ImportResource
This is a new comment added by Spring 3.0 to import one or more Spring configuration files. This is very useful for Spring Boot to be compatible with old projects, because some configurations can only be imported with this comment, because they cannot be configured in the form of Java Config.
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