spring-boot.md

The spring-boot-starter-parent is a great way to use Spring Boot, but it might not be suitable all of the time. Sometimes you may need to inherit from a different parent POM, or you might not like our default settings. In those cases, “Using Spring Boot without the Parent POM” for an alternative solution that uses an import scope. you can still keep the benefit of the dependency management (but not the plugin management) by using a scope=import dependency, as follows:

<dependencyManagement>
		<dependencies>
		<dependency>
			<!-- Import dependency management from Spring Boot -->
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-dependencies</artifactId>
			<version>2.1.0.BUILD-SNAPSHOT</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

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With that setup, you can also override individual dependencies by overriding a property in your own project. For instance, to upgrade to another Spring Data release train, you would add the following to your pom.xml:

<properties>
	<spring-data-releasetrain.version>Fowler-SR2</spring-data-releasetrain.version>
</properties>

Check the spring-boot-dependencies pom for a list of supported properties.

The preceding sample setup does not let you override individual dependencies by using a property, as explained above. To achieve the same result, you need to add an entry in the dependencyManagement of your project before the spring-boot-dependencies entry. For instance, to upgrade to another Spring Data release train, you could add the following element to your pom.xml:

<dependencyManagement>
	<dependencies>
		<!-- Override Spring Data release train provided by Spring Boot -->
		<dependency>
			<groupId>org.springframework.data</groupId>
			<artifactId>spring-data-releasetrain</artifactId>
			<version>Fowler-SR2</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-dependencies</artifactId>
			<version>2.1.0.BUILD-SNAPSHOT</version>
			<type>pom</type>
			<scope>import</scope>
		</dependency>
	</dependencies>
</dependencyManagement>

Importing Additional Configuration Classes

You need not put all your @Configuration into a single class. The @Import annotation can be used to import additional configuration classes. Alternatively, you can use @ComponentScan to automatically pick up all Spring components, including @Configuration classes.

Importing XML Configuration

If you absolutely must use XML based configuration, we recommend that you still start with a @Configuration class. You can then use an @ImportResource annotation to load XML configuration files.

If you structure your code as suggested above (locating your application class in a root package), you can add @ComponentScan without any arguments. All of your application components (@Component, @Service, @Repository, @Controller etc.) are automatically registered as Spring Beans.

The @SpringBootApplication annotation is equivalent to using @Configuration, @EnableAutoConfiguration, and @ComponentScan with their default attributes.

Spring Boot VS Spring

Spring Boot 是针对于Spring搭建一套服务所需要进行的重复繁琐操作的改进

• spring boot starter可以引入一套兼容的各组件依赖
• spring boot 约定优于配置，提供了一套默认的配置，即插即用。如需自定义配置，只需要对对应参数进行设置即可。
• spring boot 使用了内嵌容器
• spring boot actuator对服务进行了监控