自定义starter

自定义类

package com.myboot;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@ConfigurationProperties(prefix = "spring.person")
public class PersonProperties {
    // 姓名
    private String name;
    // 年龄
    private int age;
    // 性别
    private String sex = "M";

    // Getter & Setter

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

    public void setAge(int age) {
        this.age = age;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public String getSex() {
        return sex;
    }
}

package com.myboot;

public class PersonService {
    private PersonProperties properties;

    public PersonService() {
    }

    public PersonService(PersonProperties properties) {
        this.properties = properties;
    }

    public void sayHello(){
        System.out.println("大家好，我叫: " + properties.getName() + ", 今年" + properties.getAge() + "岁"
                + ", 性别: " + properties.getSex());
    }
}

package com.myboot;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
//ConfigurationProperties的辅助类，用于在容器中生成bean
@EnableConfigurationProperties(PersonProperties.class)
//判断类是否存在，如果存在装配到容器中，即生成bean
@ConditionalOnClass(PersonService.class)

//判断配置是否有效，即装配开关
@ConditionalOnProperty(prefix = "spring.person", value = "enabled", matchIfMissing = true)
public class PersonServiceAutoConfiguration {

    @Autowired
    private PersonProperties properties;

    @Bean
    @ConditionalOnMissingBean(PersonService.class)  // 当容器中没有指定Bean的情况下，自动配置PersonService类
    public PersonService personService() {
        PersonService personService = new PersonService(properties);
        return personService;
    }
}

解释：

@EnableConfigurationProperties:使ConfigurationProperties生效，并且将关联的类实例化放在容器中
@Conditional(TestCondition.class)

这句代码可以标注在类上面，表示该类下面的所有@Bean都会启用配置，也可以标注在方法上面，只是对该方法启用配置。

@ConditionalOnBean（仅仅在当前上下文中存在某个对象时，才会实例化一个Bean）
@ConditionalOnClass（某个class位于类路径上，才会实例化一个Bean）
@ConditionalOnExpression（当表达式为true的时候，才会实例化一个Bean）
@ConditionalOnMissingBean（仅仅在当前上下文中不存在某个对象时，才会实例化一个Bean）
@ConditionalOnMissingClass（某个class类路径上不存在的时候，才会实例化一个Bean）
@ConditionalOnNotWebApplication（不是web应用）
@ConditionalOnProperty：使@Configuration生效

编写启动配置文件
/META-INF/spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.myboot.PersonServiceAutoConfiguration

解释：
spring.factories的作用：
springboot在初始化的时候SpringFactoriesLoader会去加载spring.factories中的工厂类的实现方法
pom 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>

    <groupId>com.mybootstarter</groupId>
    <artifactId>my-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-autoconfigure</artifactId>
            <version>2.1.6.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <version>2.1.6.RELEASE</version>
            <optional>true</optional>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

测试项目

在测试项目中引入此GAV
测试类如下

package com.mystarter.test.myspringbootstartertest;

import com.myboot.PersonService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.Resource;

@SpringBootApplication
@RestController
@RequestMapping("starter")
public class MySpringbootStartertestApplication {
    @Resource
    private PersonService personService;

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

    @RequestMapping("t")
    public Object starterT() {
         personService.sayHello();
         return null;

    }
}