Spring Boot

April 28, 2023

https://spring.io/projects/spring-boot
中文：https://springdoc.cn/spring-boot/
How-to：https://springdoc.cn/spring-boot/howto.html

创建项目

https://start.spring.io/
镜像：https://start.springboot.io/

xml

<!-- pom.xml -->

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.0.6</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>17</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>RELEASE</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

java

@RestController
@SpringBootApplication
public class MyApplication {

    @RequestMapping("/")
    String home() {
        return "Hello World!";
    }

    public static void main(String[] args) {
         Logger logger = LoggerFactory.getLogger(MyApplication.class);

        // 这些log不会被spring boot捕获
        logger.trace("before trace");
        logger.debug("before debug");
        logger.info("before info");
        logger.warn("before warn");
        logger.error("before error");

        SpringApplication.run(MyApplication.class, args);

        // 这些log会被spring boot捕获，由spring boot处理
        logger.trace("after trace");
        logger.debug("after debug");
        logger.info("after info");
        logger.warn("after warn");
        logger.error("after error");
    }

}

运行下面的命令，可以在项目根目录的 target 目录下得到可执行 jar 包

mvn package

一个项目典型的布局如下

com
 +- example
     +- myapplication
         +- MyApplication.java
         |
         +- customer
         |   +- Customer.java
         |   +- CustomerController.java
         |   +- CustomerService.java
         |   +- CustomerRepository.java
         |
         +- order
             +- Order.java
             +- OrderController.java
             +- OrderService.java
             +- OrderRepository.java

@SpringBootApplication 注解默认会扫描当前类下的所有子包

配置 Spring Boot

starter 默认生成了空文件 application.properties
也可以通过 application.yml 进行配置更直观

yaml

server:
    port: 8080

spring:
    application:
        name: ${APP_NAME:unnamed}
    datasource:
        url: jdbc:hsqldb:file:testdb
        username: sa
        password:
        driver-class-name: org.hsqldb.jdbc.JDBCDriver
        hikari:
            auto-commit: false
            connection-timeout: 3000
            validation-timeout: 3000
            max-lifetime: 60000
            maximum-pool-size: 20
            minimum-idle: 1
logging:
    level:
        root: INFO

使用开发者工具（Developer Tools）

https://springdoc.cn/spring-boot/using.html#using.devtools

xml

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>
</dependencies>

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