Spring Boot requires a separate container to run it?
May not be required, it built Tomcat / Jetty like container. By introducing the pom.xml dependency:
<- spring-boot-starter- web:! represents the web module, containing a number of JAR package in this module ->
<- There are spring-related jar, built tomcat server, jackson, these web projects! common features are automatically incorporated ->
<dependency>
<the groupId> org.springframework.boot </ the groupId>
<the artifactId> Starter-Spring-Boot-Web </ the artifactId>
</ dependency>
Core comment Spring Boot Which? It mainly consists of several notes which composed?
Start class above annotations are @SpringBootApplication, it is also the core Spring annotation Boot, mainly contains the following three combinations of notes:
@SpringBootConfiguration
@EnableAutoConfiguration: Open function automatically configured, an option can also turn off auto-configuration, such as the data source close auto-configuration feature: @SpringBootApplication(exclude = { DataSourceAutoConfiguration.class }).
@ComponentScan: Spring component scans.
How to understand the meaning Starters in Spring Boot?
What Starters that?
Starters can be understood as a starter, which contains a series of applications which can be integrated into the dependencies, you can integrate Spring and other one-stop technology, without the need to find that sample code and dependencies. If you want to use the Spring JPA to access the database, just add spring-boot-starter-data-jpastarter depend ready to use. Starters include the dependence of many projects need to use, they can continue to run fast, are supported by a series of management transitive dependencies.
Starters naming?
Spring Boot are based on the official starter spring-boot-starter-named, it represents a particular type of application. Third-party launcher does not start with spring-boot name, they are the official Spring Boot reserved. On average, a third party should be so named, like the mybatis mybatis-spring-boot-starter.
Starters Category:
1) provided by the initiator Spring boot
| Initiator name | Functional Description |
|---|---|
| spring-boot-starter | The core module includes an automatic configuration support, log database and support for YAML configuration file. |
| spring-boot-starter-amqp | Supports AMQP protocol (Advanced Message Queuing Protocol) via spring-rabbit |
| spring-boot-starter-aop | I.e. oriented programming support AOP, comprising a spring-aop and AspectJ |
| spring-boot-starter-artemis | JMS support through Apache Artemis API (Java Message Service API) |
| spring-boot-starter-batch | Support Spring Batch, including HSQLDB database |
| spring-boot-starter-cache | Spring's support for Cache abstract |
| spring-boot-starter-cloud-connectors | Support Spring Cloud Connectors, simplified in such as Cloud Foundry or Heroku cloud platform connectivity services |
| spring-boot-starter-data-elasticsearch | Support ElasticSearch search and analysis engine, including spring-data-elasticsearch |
| spring-boot-starter-data-gemfire | GemFire supports distributed data storage, comprising a spring-data-gemfire |
| spring-boot-starter-data-jpa | 支持 JPA (Java Persistence API), 包括 spring-data-jpa, spring-orm, Hibernate |
| spring-boot-starter-data-solr | Support Apache Solr search platform, including spring-data-solr |
| spring-boot-starter-data-mongodb | MongoDB support data, including spring-data-mongodb |
| spring-boot-starter-data-rest | By spring-data-rest-webmvc, supported by data warehouse exposed Spring Data REST |
| spring-boot-starter-redis | Redis key-value store database support, including spring-redis |
| spring-boot-starter-data-jdbc | Supports JDBC database access |
| spring-boot-starter-jta-atomikos | By Atomikos support JTA distributed transaction processing |
| spring-boot-starter-jta-bitronix | By Bitronix support JTA distributed transaction processing |
| spring-boot-starter-security | Support spring-security |
| spring-boot-starter-test | Conventional tests rely support, including JUnit, Hamcrest, Mockito and spring-test module |
| spring-boot-starter-velocity | Velocity template engine support |
| spring-boot-starter-freemarker | Support FreeMarker template engine |
| spring-boot-starter-thymeleaf | Support Thymeleaf template engine, including integration with Spring |
| spring-boot-starter-mustache | Support Mustache template engine |
| spring-boot-starter-web | Support full-stack Web development, including Tomcat and spring-webmvc |
| spring-boot-starter-websocket | WebSocket support development |
| spring-boot-starter-ws | Spring Web Services Support |
| spring-boot-starter-groovy-templates | Groovy template engine support |
| spring-boot-starter-hateoas | Supports HATEOAS of RESTful Web services via spring-hateoas |
| spring-boot-starter-hornetq | By HornetQ JMS support |
| spring-boot-starter-log4j | Support Log4J logging framework |
| spring-boot-starter-logging | Introduces Spring Boot default logging framework Logback |
| spring-boot-starter-integration | It supports common spring-integration module |
| spring-boot-starter-jersey | Support services framework Jersey RESTful Web |
| spring-boot-starter-mail | Support javax.mail module |
| spring-boot-starter-mobile | Support spring-mobile |
| spring-boot-starter-social-facebook | 支持 spring-social-facebook |
| spring-boot-starter-social-linkedin | Support spring-social-linkedin |
| spring-boot-starter-social-twitter | Support spring-social-twitter |
| spring-boot-starter-actuator | Product line for increasing the related functions, such as measurement and monitoring |
| spring-boot-starter-remote-shell | Added support of remote ssh shell |
| spring-boot-starter-tomcat | 引入了 Spring Boot 默认的 HTTP 引擎 Tomcat |
| spring-boot-starter-jetty | 引入了Jetty HTTP引擎（用于替换Tomcat） |
| spring-boot-starter-undertow | 引入了Undertow HTTP引擎（用于替换Tomcat) |
4）其他第三方启动器（略）
Spring Boot实现热部署有哪几种方式？
在Spring Boot实现代码热部署是一件很简单的事情，代码的修改可以自动部署并重新热启动项目。
1）引用devtools依赖
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
修改一个java类时就可以实现热更新了。
2）自定义配置热部署
以下配置用于自定义配置热部署，可以不设置。
#热部署开关，false即不启用热部署
spring.devtools.restart,enabled: true
#指定热部署的目录
#spring.devtools.restart.additional-paths: src/main/java
#指定目录不更新
spring.devtools.restart.exclude: test/**
3）Intellij Idea工具修改实现热部署
需要改以下两个位置：
勾上自动编译或者手动重新编译
File > Settings > Compiler-Build Project automatically
注册使用快捷键的方式：
ctrl + shift + alt + / > Registry > 勾选Compiler autoMake allow when app running
注意事项：
1）生产环境devtools将被禁用，如java -jar方式或者自定义的类加载器等都会识别为生产环境。
2）打包应用默认不会包含devtools，除非你禁用SpringBoot Maven插件的excludeDevtools属性。
3）Thymeleaf无需配置 spring.thymeleaf.cache:false，devtools默认会自动设置，参考完整属性。
下面是devtools自动配置的完整源码：
@Order(Ordered.LOWEST_PRECEDENCE)
public class DevToolsPropertyDefaultsPostProcessor implements EnvironmentPostProcessor {
private static final Map<String, Object> PROPERTIES;
static {
Map<String, Object> devToolsProperties = new HashMap<>();
devToolsProperties.put("spring.thymeleaf.cache", "false");
devToolsProperties.put("spring.freemarker.cache", "false");
devToolsProperties.put("spring.groovy.template.cache", "false");
devToolsProperties.put("spring.mustache.cache", "false");
devToolsProperties.put("server.servlet.session.persistent", "true");
devToolsProperties.put("spring.h2.console.enabled", "true");
devToolsProperties.put("spring.resources.cache.period", "0");
devToolsProperties.put("spring.resources.chain.cache", "false");
devToolsProperties.put("spring.template.provider.cache", "false");
devToolsProperties.put("spring.mvc.log-resolved-exception", "true");
devToolsProperties.put("server.servlet.jsp.init-parameters.development", "true");
devToolsProperties.put("spring.reactor.stacktrace-mode.enabled", "true");
PROPERTIES = Collections.unmodifiableMap(devToolsProperties);
}
@Override
public void postProcessEnvironment(ConfigurableEnvironment environment,
SpringApplication application) {
if (isLocalApplication(environment) && canAddProperties(environment)) {
PropertySource<?> propertySource = new MapPropertySource("refresh",
PROPERTIES);
environment.getPropertySources().addLast(propertySource);
}
}
private boolean isLocalApplication(ConfigurableEnvironment environment) {
return environment.getPropertySources().get("remoteUrl") == null;
}
private boolean canAddProperties(Environment environment) {
return isRestarterInitialized() || isRemoteRestartEnabled(environment);
}
private boolean isRestarterInitialized() {
try {
Restarter restarter = Restarter.getInstance();
return (restarter != null && restarter.getInitialUrls() != null);
}
catch (Exception ex) {
return false;
}
}
private boolean isRemoteRestartEnabled(Environment environment) {
return environment.containsProperty("spring.devtools.remote.secret");
}
}
4）devtools会在windows资源管理器占用java进程，在开发工具里面杀不掉，只能手动kill掉，不然重启会选成端口重复绑定报错。
Spring Boot如何定义多套不同环境配置？
简单来说，Profile就是Spring Boot可以对不同环境或者指令来读取不同的配置文件。
假如有开发、测试、生产三个不同的环境，需要定义三个不同环境下的配置。
1）基于properties文件类型可以另外建立3个环境下的配置文件：
applcation.properties application-dev.properties application-test.properties application-prod.properties
然后在applcation.properties文件中指定当前的环境spring.profiles.active=test，这时候读取的就是application-test.properties文件。
2）基于yml文件类型，只需要一个applcation.yml文件即可，推荐此方式。关注微信公众号“Java精选”（w_z90110），回复关键字领取资料：如Mysql，Hadoop，Dubbo，CAS源码等等，免费领取视频教程、资料文档和项目源码。Java面试题持续更新中...
spring:
profiles:
active: prod
---
spring:
profiles: dev
server:
port: 8080
---
spring:
profiles: test
server:
port: 8081
---
spring.profiles: prod
spring.profiles.include:
- proddb
- prodmq
server:
port: 8082
---
spring:
profiles: proddb
db:
name: mysql
---
spring:
profiles: prodmq
mq:
address: localhost
其中dev代表开发，test代表测试，prod代表正式环境。此时读取的就是prod的配置，prod包含proddb,prodmq，此时可以读取proddb,prodmq下的配置。也可以同时激活三个配置，如下：
spring.profiles.active: prod,proddb,prodmq
3）基于Java代码，在JAVA配置代码中也可以加不同Profile下定义不同的配置文件，@Profile注解只能组合使用@Configuration和@Component注解。
@Configuration
@Profile("prod")
public class ProductionConfiguration {
// ...
}
4）指定Profile
main方法启动方式：在Eclipse Arguments里面添加
--spring.profiles.active=prod
插件启动方式：
spring-boot:run -Drun.profiles=prod
jar运行方式：
java -jar xx.jar --spring.profiles.active=prod
除了在配置文件和命令行中指定Profile，还可以在启动类中写死指定，通过SpringApplication.setAdditionalProfiles方法
SpringApplication.class
public void setAdditionalProfiles(String... profiles) {
this.additionalProfiles = new LinkedHashSet<String>(Arrays.asList(profiles));
}