一、springboot starter

springboot starter：引入相关依赖和初始化配置（自动配置）

一般可以根据starter区分是spring官方还是第三方：

二、自定义一个简单的starter

一、创建一个hello-spring-boot-starter的maven项目并配置pom.xml文件

<?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 
                             http://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>2.2.2.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>cn.itcast</groupId>
    <artifactId>hello-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
        </dependency>
    </dependencies>
</project>

2、创建配置属性类HelloProperties

/*
 *读取配置文件转换为bean
 * */
@ConfigurationProperties(prefix = "hello")
public class HelloProperties {
    private String name;
    private String address;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    @Override
    public String toString() {
        return "HelloProperties{" +
                "name='" + name + '\'' +
                ", address='" + address + '\'' +
                '}';
    }
}

3、创建服务类HelloService

public class HelloService {
    private String name;
    private String address;

    public HelloService(String name, String address) {
        this.name = name;
        this.address = address;
    }

    public String sayHello(){
        return "你好！我的名字叫 " + name + "，我来自 " + address;
    }
}

4、创建自动配置类HelloServiceAutoConfiguration

/*
* 配置类，基于Java代码的bean配置
* */

@Configuration
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfiguration {
    private HelloProperties helloProperties;

    //通过构造方法注入配置属性对象HelloProperties
    public HelloServiceAutoConfiguration(HelloProperties helloProperties) {
        this.helloProperties = helloProperties;
    }

    //实例化HelloService并载入Spring IoC容器
    @Bean
    @ConditionalOnMissingBean
    public HelloService helloService(){
        return new HelloService(helloProperties.getName(),helloProperties.getAddress());
    }
}

5、在resources目录下创建META-INF/spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
cn.itcast.config.HelloServiceAutoConfiguration

然后

二、新建一个maven项目去使用该jar包

1、pom：

<?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 http://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>2.2.2.RELEASE</version>
        <relativePath/>
    </parent>
    <groupId>cn.itcast</groupId>
    <artifactId>myapp</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <!--导入自定义starter-->
        <dependency>
            <groupId>cn.itcast</groupId>
            <artifactId>hello-spring-boot-starter</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
    </dependencies>
</project>

 2、创建application.yml文件

server:
  port: 8080
hello:
  name: xiaoming
  address: beijing

3、controller

package cn.itcast.controller;

import cn.itcast.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/hello")
public class HelloController {
    //HelloService在我们自定义的starter中已经完成了自动配置，所以此处可以直接注入
    @Autowired
    private HelloService helloService;

    @GetMapping("/say")
    public String sayHello(){
        return helloService.sayHello();
    }
}

4、启动类

package cn.itcast;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class HelloApplication {
    public static void main(String[] args) {
        SpringApplication.run(HelloApplication.class,args);
    }
}

5、执行启动类main方法，访问地址http://localhost:8080/hello/say