SpringBoot自动配置自定义Starter

下面创建一个 spring-boot-starter-hello 的启动器，这个启动器的Person与配置文件的属性绑定，可以供引入这个启动器的项目进行配置。HelloService 使用sayHello方法输出Person内容。HelloAautoConfiguration是配置类，产生HelloService的bean。

项目结构：

首先创建一个SpringBoot项目，pom要做一些修改：

添加如下两个依赖：

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

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-configuration-processor</artifactId>
   <optional>true</optional>
</dependency>

spring-boot-starter：包含自动配置的基本包，spring-boot-configuration-processor：添加这个依赖会在配置文件产生提示。

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>1.5.19.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<groupId>cn.cld</groupId>
	<artifactId>spring-boot-starter-hello</artifactId>
	<version>0.0.1-SNAPSHOT</version>

	<properties>
		<java.version>1.8</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-configuration-processor</artifactId>
			<optional>true</optional>
		</dependency>

	</dependencies>

</project>

Person.java

package cn.cld;

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

@ConfigurationProperties(prefix = "person")
public class Person {
    private String id="DEFAULT";
    private String name="DEFAULT1";

    public String getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

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

@ConfigurationProperties(prefix = "person") 把Person类和配置文件绑定。


HelloService.java

package cn.cld;

public class HelloService {
    private Person person;

    public Person getPerson() {
        return person;
    }

    public void setPerson(Person person) {
        this.person = person;
    }

    public String sayHello(){
        return "Say : "+this.person;
    }
}

HelloAautoConfiguration.java

package cn.cld;

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.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
@EnableConfigurationProperties(Person.class)
@ConditionalOnWebApplication
@ConditionalOnClass(HelloService.class)
@ConditionalOnProperty(prefix = "person",value = {"id","name"},matchIfMissing=true)
public class HelloAautoConfiguration {
    @Autowired
    private Person person;

    @Bean
    @ConditionalOnMissingBean(HelloService.class)
    public HelloService helloService(){
        HelloService hs=new HelloService();
        hs.setPerson(person);
        return hs;
    }

    public int getOrder(){
        return 0;
    }
}

@EnableConfigurationProperties(Person.class) 把与配置文件绑定的Person类导入到容器；

@ConditionalOnWebApplication 只有WEB应用，该配置类才生效；

@ConditionalOnClass(HelloService.class) 只有存在HelloService这个类配置类才生效；

@ConditionalOnProperty(prefix = "person",value = {"id","name"},matchIfMissing=true) 配置中存在person前缀，名称有id有name时候才生效，true说明即使不存在也生效，false不存在报错。

@ConditionalOnMissingBean(HelloService.class)容器里不存在HelloService的bean时候才创建该Bean.

最后创建META-INF目录在里面创建如下文件

spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=cn.cld.HelloAautoConfiguration

最后，其他SpringBoot项目引入这个自定义启动器，就可以注入HelloService进行sayHello调用，并可以在配置文件里配置person的值。