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定义自己的starter

标签：SpringBoot
2019-03-05

原理

  • springboot启动默认只会扫描本项目下的带@Configuration注解的类，如果自定义starter，不在本工程中，是无法加载的，故要配置META-INF/spring.factories配置文件

  • springboot启动时会去依赖的starter包中寻找 resources/META-INF/spring.factories，自动配置bean

  • @Configuration与@Bean->基于java代码的bean配置

  • @Conditional->设置自动配置条件依赖

  • @EnableConfigurationProperties与@ConfigurationProperties->读取配置文件转换为bean

  • @EnableAutoConfiguration->实现bean发现与加载。

添加依赖

<groupId>com.qif</groupId>
#命名规范 name-spring-boot-starter
<artifactId>qif-spring-boot-starter</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>jar</packaging>

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

配置文件读取类

@ConfigurationProperties(prefix = "com.qif")
@Data
public class QifProperties {
    private boolean enabled;
    private String name;
}

编写功能类

public class QifService {
    private String name;

    public QifService(String name) {
        this.name = name;
    }
    
    public void sayHello() {
       System.out.println("hello:"+name)
    }
    
}

编写AutoConfigure类

@Configuration
#当classpath下发现该类的情况下进行自动配置
@ConditionalOnClass(QifService.class)
@EnableConfigurationProperties(QifProperties.class)
@ConditionalOnProperty(prefix = "com.qif", value = "enabled", havingValue = "true")
public class StarterAutoConfigure {

    @Autowired
    private QifProperties properties;

    @Bean
	#当Spring Context中不存在该Bean时
    @ConditionalOnMissingBean
    QifService qifService(){
        return new QifService(properties.getName());
    }

}

在resources/META-INF/下创建spring.factories文件并编写内容

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.qif.StarterAutoConfigure

测试

#将自定义starter依赖添加到项目中
<dependency>
    <groupId>com.qif</groupId>
    <artifactId>qif-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>
 </dependency>

#application.yml 配置文件中添加配置信息
com
  qif
    enabled: true
    name： quincy

#JUNIT测试
@Autowired
private QifService qifService;

@Test
public void starterTest() {
    System.out.println(qifService.sayHello());
}

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