参考：https://www.cnblogs.com/yuansc/p/9088212.html
STEP1：创建一个SpringBoot 项目，并添加下面两个依赖到pom.xml文件当中。
<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>
STEP2: 编写Service类
···
public class StarterService {
private String config;
public StarterService(String config) {
this.config = config;
}
public String[] split(String separatorChar) {
return StringUtils.split(this.config, separatorChar);
}
}
···
STEP3：编写配置文件读取类
@ConfigurationProperties("example.service")
public class StarterServiceProperties {
private String config;
public void setConfig(String config) {
this.config = config;
}
public String getConfig() {
return config;
}
}
STEP4：编写AutoConfigure类
@Configuration
@ConditionalOnClass(StarterService.class)
@EnableConfigurationProperties(StarterServiceProperties.class)
public class StarterAutoConfigure {
@Autowired
private StarterServiceProperties properties;
@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "example.service", value = "enabled", havingValue = "true")
StarterService starterService (){
return new StarterService(properties.getConfig());
}
}
解释一下代码中用到的几个注解：
•@ConditionalOnClass，当classpath下发现该类的情况下进行自动配置。
•@ConditionalOnMissingBean，当Spring Context中不存在该Bean时。
•@ConditionalOnProperty(prefix = "example.service",value = "enabled",havingValue = "true")，当配置文件中example.service.enabled=true时。
