springboot 自定义starter之AutoConfiguration【原】

八、自定义starter

AutoConfiguration：

1、这个场景需要使用到的依赖是什么？

没有特别依赖的配置

2、如何编写自动配置

@Configuration  //指定这个类是一个配置类
@ConditionalOnXXX  //在指定条件成立的情况下自动配置类生效
@AutoConfigureAfter({YYY.class,ZZZ.class})  //指定自动配置类的顺序，在哪个自动配置类之后才配置
@Bean  //给容器中添加组件,写成@Component也可
​
@ConfigurationPropertie // 结合相关xxxProperties类来绑定相关的配置
@EnableConfigurationProperties //让xxxProperties生效直接加入到容器中，可以直接使用@Autowired自动包装该xxxProperties类
​
//自动配置类要能加载
//将需要启动就加载的自动配置类，配置在META-INF/spring.factories  （比如spring-boot-autoconfigure-1.5.14.RELEASE.jar包的类路径下的/META-INF/spring.factories文件）
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\

模式：

starter启动器只用来做依赖导入；可以是一个空jar文件，仅提供辅助性依赖管理，这些依赖可能用于自动装配或其它类库。所以建模块时建成普通manven即可。

autoconfigurer自动配置模块必需要依赖spring-boot-starter, 所以建模块时最好建成springboot项目。

starter和autoconfigurer分成两个项目， 是为了形成一个starter对应对多autoconfigurer的后期扩展，方便管理。以后别人引用时只需要引用starter，而不用关心autoconfigurer。

建议命名规则

	命名规则	定义名	举例
官方starter	spring-boot-starter-OfficalDefinition	名字在后面	spring-boot-starter-jdbc
自定义starter	MyDefinition-spring-boot-starter	名字在前面	starter叫mybatis-spring-boot-starter

项目说明

1、my-spring-boot-starter-autoconfigurer  自动配置模块

2、my-spring-boot-starter 场景启动器starter模块 ，依赖my-spring-boot-starter-autoconfigurer

3、starter-demo 主项目 依赖my-spring-boot-starter

starter-demo-2019-6-12 15-17-11.snag

步骤

1、自动配置模块 my-spring-boot-starter-autoconfigurer

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 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>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>my-spring-boot-starter-autoconfigurer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>my-spring-boot-starter-autoconfigurer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <!--autoconfigurer只需要依赖原生的spring-boot-starter-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <!-- 配置文件自动映射 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-configuration-processor</artifactId>
            <optional>true</optional>
        </dependency>
    </dependencies>

</project>

Ticket.java

package com.example.simple.bean;

import java.io.Serializable;

public class Ticket implements Serializable {
    public Integer id;
    public String name;
    private String type;

    public Ticket() {
    }

    public Ticket(Integer id, String name, String type) {
        this.id = id;
        this.name = name;
        this.type = type;
    }
//get set  toString ....
}

TicketProperties.java

package com.example.simple.bean;

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

//和application.properties或application.yml产生关联
@ConfigurationProperties(prefix = "com.ticket")
public class TicketProperties {
    Integer id;//可以用 application.properties中com.ticket.id=xxx 的配置自动赋值
    String name;//可以用 application.properties中com.ticket.name=xxx 的配置自动赋值
    String type;//可以用 application.properties中com.ticket.type=xxx 的配置自动赋值

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }
}

ITicketService.java

接口

package com.example.simple.service;

import com.example.simple.bean.Ticket;
import com.example.simple.bean.TicketProperties;

public interface ITicketService {
    public Ticket getDefaultTicket(String type);

    public TicketProperties getTicketProperties();

    public void setTicketProperties(TicketProperties ticketProperties);
}

PianoTicketService.java

package com.example.simple.service;

import com.example.simple.bean.Ticket;
import com.example.simple.bean.TicketProperties;

/**
 * 为了在 TicketServiceAutoConfiguration 的@Bean注解的方法中使用以返回该对象到IOC容器中，
 * 最终可以让其它依赖后的项目的Controller,Service等组件使用@Autowired自动装配该Bean
 */
public class PianoTicketService implements ITicketService {
    TicketProperties ticketProperties;

    @Override
    public Ticket getDefaultTicket(String type){//用于其它项目的Controller中
        Ticket ticket = new Ticket(9999,ticketProperties.getName(),ticketProperties.getType());
        return ticket;
    }

    @Override
    public TicketProperties getTicketProperties() { //get方法
        return ticketProperties;
    }

    @Override
    public void setTicketProperties(TicketProperties ticketProperties) {//set方法
        this.ticketProperties = ticketProperties;
    }

}

ViolinTicketService.java

package com.example.simple.service;

import com.example.simple.bean.Ticket;
import com.example.simple.bean.TicketProperties;

public class ViolinTicketService implements ITicketService {
    TicketProperties ticketProperties;

    @Override
    public Ticket getDefaultTicket(String type){//用于其它项目的Controller中
        Ticket ticket = new Ticket(9999,ticketProperties.getName(),ticketProperties.getType());
        return ticket;
    }

    @Override
    public TicketProperties getTicketProperties() {//get方法
        return ticketProperties;
    }

    @Override
    public void setTicketProperties(TicketProperties ticketProperties) {//set方法
        this.ticketProperties = ticketProperties;
    }

}

TicketServiceAutoConfiguration.java

package com.example.simple.config;

import com.example.simple.bean.TicketProperties;
import com.example.simple.service.ITicketService;
import com.example.simple.service.PianoTicketService;
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.ConditionalOnWebApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration//标注这是一个配置类，这个类的位置不需要在启动类MySpringBootApplication的子包下，因为由META-INF/spring.factories指定了加载位置
@ConditionalOnWebApplication//添加一些条件（也可以不加）web项目时才有效
@ConditionalOnClass({ITicketService.class})//ITicketService.class存在时本配置才有效
//@ConditionalOnMissingClass({"com.example.simple.service.ITicketService"})//指定类不存在的时候配置才有效
@EnableConfigurationProperties(TicketProperties.class)//让TicketProperties在当前配置中直接生效
public class TicketServiceAutoConfiguration {//声明自动配置类

    @Autowired
    TicketProperties ticketProperties;//自动包装

    //声明自动装配的Bean,这样当于在项目启动时就内置加载了该Bean
    @Bean
    //这个配置就是SpringBoot可以优先使用自定义Bean的核心所在，如果没有我们的自定义Bean ITicketService.class 存在, 那么才会自动配置一个新的Bean
    @ConditionalOnMissingBean(ITicketService.class)
    public ITicketService ticketService() {
        System.out.println("my-spring-boot-starter-autoconfigurer的bean:ticketService装配到容器成功");
        ITicketService ticketService = new PianoTicketService();//声明对象
        ticketService.setTicketProperties(ticketProperties);//设置属性
        return ticketService;//返回对象
    }

    // 参考: https://blog.csdn.net/xcy1193068639/article/details/81517456
    //@ConditionOnBean在判断list的时候，如果list没有值，返回false，否则返回true
    //@ConditionOnMissingBean在判断list的时候，如果list没有值，返回true，否则返回false，其他逻辑都一样

}

spring.factories

创建文件夹及文件 src\main\resources\META-INF\spring.factories  , 目录不可更改

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.example.simple.config.TicketAutoConfiguration

如果有多个自动配置类

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.xxx.yyy.Zzz1AutoConfiguration,\
com.xxx.yyy.Zzz2AutoConfiguration,\
com.xxx.yyy.Zzz3AutoConfiguration

2、启动器模块 my-spring-boot-starter

可以包含多个autoconfigurer模块, 方便其它项目引用

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
​
    <groupId>com.example</groupId>
    <artifactId>my-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>
​
    <!--引入自动配置模块-->
    <dependencies>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>my-spring-boot-starter-autoconfigurer</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>

        <!--
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>my-spring-boot-starter-other-autoconfigurer</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
        -->

    </dependencies>
</project>

3、 starter-demo

starter-demo为依赖my-spring-boot-starter的项目 , 就像正常maven项目一样, 在pom.xml添加my-spring-boot-starter即可.

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 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>2.1.5.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>starter-demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>starter-demo</name>
    <description>Demo project for Spring Boot</description>
​
    <properties>
        <java.version>1.8</java.version>
    </properties>
​
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
​
        <!--配置自定义的starter依赖-->
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>my-spring-boot-starter</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>
​
    </dependencies>
​
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
​
</project>

TicketController.java

http get访问入口 http://localhost:8080/ticket?type=piano

package com.example.starterdemo.controller;

import com.example.simple.bean.Ticket;
import com.example.simple.service.ITicketService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class TicketController {

    @Autowired
    ITicketService ticketService;

    //http://localhost:8080/ticket?type=piano
    @GetMapping(value = "/ticket")
    public Ticket getDefaultTicket(String type){
        Ticket ticket = ticketService.getDefaultTicket(type);
        return ticket;
    }
}

StarterDemoApplication.java

启动应用的类 , 启用了public ITicketService ticketService() 方法, 会在容器中添加ITicketService bean , 让默认自动配置失效, 当注释该方法后, 又可以启动自动配置.

package com.example.starterdemo;

import com.example.simple.bean.TicketProperties;
import com.example.simple.service.ITicketService;
import com.example.simple.service.PianoTicketService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class StarterDemoApplication {

    //声明自动装配的Bean,这样当于在项目启动时就内置加载了该Bean
    //本bean将会优先于my-spring-boot-starter-autoconfigurer自动装配模块的 TicketServiceAutoConfiguration 类中的ticketService bean的初始化,
    //而自动装配模块有@ConditionalOnMissingBean(ITicketService.class)条件,所以一旦配了该bean,将替换自动装配模块的bean
    //为了作出区别,本bean的初始化值不再从properties文件中获取,而是直接代码声明了.
    @Bean
    public ITicketService ticketService() {
        System.out.println("starter-demo的bean:ticketService装配到容器成功, my-spring-boot-starter-autoconfigurer的bean:ticketService不再装配");

        ITicketService ticketService = new PianoTicketService();//声明对象
        TicketProperties ticketProperties = new TicketProperties();
        ticketProperties.setId(8888);
        ticketProperties.setName("圣母颂");
        ticketProperties.setType("violin");

        ticketService.setTicketProperties(ticketProperties);//设置属性
        return ticketService;//返回对象
    }

    //http://localhost:8080/ticket?type=piano
    public static void main(String[] args) {
        SpringApplication.run(StarterDemoApplication.class, args);
    }
}

参考

SpringBoot @ConditionalOnBean、@ConditionalOnMissingBean注解源码分析与示例==>https://blog.csdn.net/xcy1193068639/article/details/81517456

我的项目git地址

我的git代码地址： https://gitee.com/KingBoBo/Spring-Boot-Starter-Demo  starter分支