SpringBoot系列 - 自定义starter

前言

starter可以认为是一种服务，某个功能开发者不需要关注各种依赖库的处理，不需要具体的配置信息。由Springboot自定注入需要的bean。比如spring-boot-starter-jdbc这个starter的存在。我们直接使用@Autowired引入DataSource的bean就可以，Spring Boot会自动创建DataSource的实例。

实例

添加maven依赖

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

编写需要定义的Bean

public class DankunService {
    private String prefix;
    private String suffix;

    public DankunService(String prefix, String suffix) {
        this.prefix = prefix;
        this.suffix = suffix;
    }
    public String wrap(String word) {
        return prefix + word + suffix;
    }
}

编写属性类

@ConfigurationProperties("dankun.service")
public class DankunServiceProperties {
    private String prefix;
    private String suffix;

    public String getPrefix() {
        return prefix;
    }

    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }

    public String getSuffix() {
        return suffix;
    }

    public void setSuffix(String suffix) {
        this.suffix = suffix;
    }
}

编写自动配置类

@Configuration
@ConditionalOnClass(DankunService.class)
@EnableConfigurationProperties(DankunServiceProperties.class)
public class DankunAutoConfigure {
    private final DankunServiceProperties properties;

    @Autowired
    public DankunAutoConfigure(DankunServiceProperties properties) {
        this.properties = properties;
    }

    @Bean
    @ConditionalOnMissingBean
    @ConditionalOnProperty(prefix = "dankun.service", value = "enabled",havingValue = "true")
    DankunService dankunService() {
        return new DankunService(properties.getPrefix(), properties.getSuffix());
    }
}

添加spring.factories

最后一步，在resources/META-INF/下创建spring.factories文件

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.dankun.autoconfig.DankunAutoConfigure

使用

修改application.yml配置文件，添加如下内容：

example.service:
  enabled: true
  prefix: ppp
  suffix: sss

测试类

@SpringBootTest
public class ApplicationTests {
    
    private DankunService dankunService;

    
    public void testStarter() {
        System.out.println(dankunService.wrap("hello"));
    }
}