Spring Boot 自定義Starter

為什么要自定義Starter

Spring Boot Starter 是一種簡(jian)化依賴管理(li)和自動配置的機制。下面詳細介紹如何創建(jian)自定義 Starter。

Starter 的基本概念

命名規范

官方 Starter: spring-boot-starter-{name}
自定義 Starter: {name}-spring-boot-starter

核心組件

autoconfigure 模塊: 包(bao)含自動(dong)配(pei)置邏輯

starter 模(mo)塊: 只包含依(yi)賴(lai)管理

創建自定義 Starter

項目結構

my-starter/
├── my-spring-boot-autoconfigure/
│   ├── src/main/java/
│   │   └── com/example/mystarter/
│   └── pom.xml
└── my-spring-boot-starter/
    ├── src/main/resources/
    │   └── META-INF/
    │       └── spring.factories
    └── pom.xml

自動配置模塊

<!-- my-spring-boot-autoconfigure/pom.xml -->
<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>

配置屬性類

@ConfigurationProperties(prefix = "my.service")
public class MyServiceProperties {
    private String prefix = "Hello";
    private String suffix = "!";
    
    // getters and setters
    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; }
}

服務類

public class MyService {
    private final String prefix;
    private final String suffix;
    
    public MyService(String prefix, String suffix) {
        this.prefix = prefix;
        this.suffix = suffix;
    }
    
    public String wrap(String message) {
        return prefix + " " + message + " " + suffix;
    }
}

自動配置類

@Configuration
@ConditionalOnClass(MyService.class)
@EnableConfigurationProperties(MyServiceProperties.class)
public class MyServiceAutoConfiguration {
    
    @Bean
    @ConditionalOnMissingBean
    public MyService myService(MyServiceProperties properties) {
        return new MyService(properties.getPrefix(), properties.getSuffix());
    }
    
    @Bean
    @ConditionalOnProperty(name = "my.service.enabled", havingValue = "true")
    @ConditionalOnMissingBean
    public MyServiceController myServiceController(MyService myService) {
        return new MyServiceController(myService);
    }
}

注冊自動配置

在 src/main/resources/META-INF/spring.factories 中(zhong)：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.example.mystarter.MyServiceAutoConfiguration

需要注意，spring boot 3.x 取消了spring.factories, 替代方案為在路徑 src/main/resources/META-INF/spring 創建一個文件org.springframework.boot.autoconfigure.AutoConfiguration.imports

把(ba)需要自動裝配一(yi)行一(yi)行放入

com.example.mystarter.MyServiceAutoConfiguration