以下例子代碼在github中，代碼鏈接
Spring Boot起步依賴(lài)（starter）大大簡(jiǎn)化了項(xiàng)目構(gòu)建中的依賴(lài)配置唁情，利用了傳遞依賴(lài)解析椅亚，把常用庫(kù)聚合在一起荆萤，組成了幾個(gè)為特定功能而定制的依賴(lài)，這些依賴(lài)項(xiàng)是使項(xiàng)目快速啟動(dòng)和運(yùn)行所需的依賴(lài)項(xiàng)，如spring-boot-starter-web起步依賴(lài)痹愚，聚合了spring-boot-starter憎瘸、spring-boot-starter-json入篮、spring-boot-starter-tomcat、spring-web幌甘、spring-webmvc等依賴(lài)潮售，使得我們的web項(xiàng)目無(wú)需引入多個(gè)web相關(guān)的依賴(lài)項(xiàng)以及為了解決版本沖突等問(wèn)題。
官方starter命名的格式是spring-boot-starter-*锅风，如spring-boot-starter-actuator酥诽、spring-boot-starter-web、spring-boot-starter-test等官方starter皱埠，平常我們自己定義的starter一般命名格式是thirdProject-spring-boot-starter
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本文示例代碼項(xiàng)目結(jié)構(gòu)是寫(xiě)一個(gè)自定義的demo-spring-boot-starter引入兩個(gè)jar包demo1和demo2肮帐，然后在project項(xiàng)目中引入demo-spring-boot-starter，項(xiàng)目結(jié)構(gòu)如圖所示：
項(xiàng)目結(jié)構(gòu).png
一、demo1項(xiàng)目
（1）pom文件如下：
<?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>
<groupId>com.fiuty</groupId>
<artifactId>demo1</artifactId>
<version>1.0-SNAPSHOT</version>
</project>
（2）demo1只有一個(gè)Student類(lèi)：
@Data
public class Student {
private String name;
private Integer age;
}
二训枢、demo2
（1）pom文件如下：
<?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>
<groupId>com.fiuty</groupId>
<artifactId>demo2</artifactId>
<version>1.0-SNAPSHOT</version>
</project>
（2）同樣托修，demo2也只有一個(gè)類(lèi)Teacher：
@Data
public class Teacher {
private String name;
private Integer age;
}
三、demo-spring-boot-starter項(xiàng)目
（1）定義starter需要引入spring-boot-starter依賴(lài)恒界、spring-boot-autoconfigure依賴(lài)以及第三方j(luò)ar demo1和demo2的依賴(lài)睦刃，如果需要配置元信息的話，還需引入spring-boot-configuration-processor依賴(lài)十酣。
（2）引入demo1和demo2的pom文件：
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo1</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo2</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
完整的pom文件如下：
<?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 https://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>2.4.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.fiuty</groupId>
<artifactId>demo-spring-boot-starter</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>demo-spring-boot-starter</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<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>
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo1</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo2</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
（3）demo-spring-boot-starter的代碼結(jié)構(gòu)如下圖所示涩拙，有一個(gè)DemoConfiguration配置類(lèi)（注入了兩個(gè)bean，demo1的student和demo2的teacher）耸采，還有兩個(gè)properties配置類(lèi)用于讀取yaml文件的配置值兴泥，還有自動(dòng)裝配類(lèi)DemoAutoConfiguration和自動(dòng)裝配配置文件spring.factories，用于項(xiàng)目啟動(dòng)時(shí)初始化bean并且被spring容器管理：
demo-spring-boot-starter的代碼結(jié)構(gòu).png
- TeacherProperties配置類(lèi)：
@ConfigurationProperties(prefix = "com.demo2")
@Configuration
@Data
public class TeacherProperties {
private String name = "defaultTeacher";
private Integer age = 30;
}
- StudentProperties配置類(lèi)
@ConfigurationProperties(prefix = "com.demo1")
@Configuration
@Data
public class StudentProperties {
private String name = "defaultStudent";
private Integer age = 10;
}
- DemoConfiguration配置類(lèi)洋幻，將yaml文件的配置值賦值到兩個(gè)bean郁轻，demo1的student和demo2的teacher：
@Configuration
//允許導(dǎo)入配置類(lèi),配置類(lèi)bean被spring容器管理
@EnableConfigurationProperties({StudentProperties.class, TeacherProperties.class})
@Slf4j
public class DemoConfiguration {
@Bean
public Student getStudent(StudentProperties studentProperties) {
Student student = new Student();
log.info("初始化student");
student.setName(studentProperties.getName());
student.setAge(studentProperties.getAge());
return student;
}
@Bean
public Teacher getTeacher(TeacherProperties teacherProperties) {
Teacher teacher = new Teacher();
teacher.setName(teacherProperties.getName());
teacher.setAge(teacherProperties.getAge());
return teacher;
}
}
- DemoAutoConfiguration自動(dòng)裝配類(lèi)
//自動(dòng)裝配,項(xiàng)目啟動(dòng)即在spring容器中注冊(cè)管理相關(guān)bean
@Import(DemoConfiguration.class)
@Configuration
public class DemoAutoConfiguration {
}
- META-INF spring.factories配置自動(dòng)裝配類(lèi)，需要注意的是spring.factories需放在resource
的目錄下文留，在引入starter的時(shí)候spring容器會(huì)注冊(cè)相關(guān)自動(dòng)裝配bean好唯。
# Auto Confiure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.fiuty.demo.spring.boot.starter.configure.DemoAutoConfiguration,\
com.fiuty.demo.spring.boot.auto.assemble.AssembleAutoConfiguration
四、project項(xiàng)目
（1）project項(xiàng)目結(jié)構(gòu)如下燥翅，引入自定義starter骑篙，在yaml文件配置starter的兩個(gè)配置類(lèi)，最后注入demo1的student bean和demo2的teacher bean森书，獲取其name和age的值：
project項(xiàng)目結(jié)構(gòu).png
（2）引入自定義的starter的pom文件如下：
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo-spring-boot-starter</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
完整的pom文件：
<?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 https://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>2.4.0</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.fiuty</groupId>
<artifactId>project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>project</name>
<description>Demo project for Spring Boot</description>
<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-starter-web</artifactId>
</dependency>
<dependency>
<groupId>com.fiuty</groupId>
<artifactId>demo-spring-boot-starter</artifactId>
<version>0.0.1-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
（3）代碼如下
- DemoController
@RestController
@RequestMapping("/api")
public class DemoController {
@Autowired
private DemoService demoService;
@GetMapping("/student/info")
public String studentInfo() {
return demoService.studentInfo();
}
@GetMapping("/teacher/info")
public String info() {
return demoService.teacherInfo();
}
}
- DemoService
public interface DemoService {
String studentInfo();
String teacherInfo();
}
- DemoServiceImpl
@Service
public class DemoServiceImpl implements DemoService {
@Autowired
private Student student;
@Autowired
private Teacher teacher;
@Override
public String studentInfo() {
return student.getName() + ":" + student.getAge();
}
@Override
public String teacherInfo() {
return teacher.getName() + ":" + teacher.getAge();
}
}
- application.yaml
com:
demo1:
age: 18
name: zhangsan
demo2:
name: lili
age: 25
在寫(xiě)yaml文件的時(shí)候可以看到有相關(guān)提示靶端，如下圖所示：
發(fā)現(xiàn)配置前綴.gif
發(fā)現(xiàn)配置1.png
發(fā)現(xiàn)配置2.png
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最后項(xiàng)目跑起來(lái)，瀏覽器訪問(wèn)：
瀏覽器1.png
瀏覽器2.png
