手写一个简单的SpringBoot Starter

现在各种自定义的starter屡见不鲜，也许就需要自己来自定义一个starter了。学习一下starter的构建必备

## starter-定义

首先需要自顶一个配置bean

```

package com.zhao.starter;

import org.springframework.boot.context.properties.ConfigurationProperties;

import org.springframework.boot.context.properties.EnableConfigurationProperties;

@EnableConfigurationProperties(StarterBean.class)

@ConfigurationProperties(prefix = "starterbean")

public class StarterBean {

private String id;

private String name;

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

@Override

public String toString() {

return "StarterBean{" +

"id='" + id + '\'' +

", name='" + name + '\'' +

'}';

}

}

```

然后需要通过Springboot自动注入的注解，以及Spring spi 的spring.factories将配置bean加入自动配置的管理

```

@Configuration

@ConditionalOnClass

public class StartBeanAutoConfiguration {

static {

System.out.println("custom auto configuration init ");

}

@Bean

public StarterBean starterBean(){

return new StarterBean();

}

}

```

资源目录下新建META-INF文件夹下spring.factories文件，

```

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.zhao.starter.StartBeanAutoConfiguration

```

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 http://maven.apache.org/xsd/maven-4.0.0.xsd">

<modelVersion>4.0.0</modelVersion>

<groupId>com.zhao</groupId>

<artifactId>starter-demo</artifactId>

<version>1.0-SNAPSHOT</version>

<dependencies>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-autoconfigure</artifactId>

<version>2.2.2.RELEASE</version>

</dependency>

</dependencies>

</project>

```

使用maven install之后就可以在新建项目时使用了。

## starter使用测试

pom定义

```

<?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.zhao</groupId>

<artifactId>starter-use-demo</artifactId>

<version>1.0-SNAPSHOT</version>

<dependencies>

<dependency>

<groupId>com.zhao</groupId>

<artifactId>starter-demo</artifactId>

<version>1.0-SNAPSHOT</version>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

<version>2.2.2.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<version>2.2.2.RELEASE</version>

<scope>test</scope>

</dependency>

</dependencies>

</project>

```

启动类

```

@SpringBootApplication

public class StarterUseApplication {

public static void main(String[] args) {

SpringApplication.run(StarterUseApplication.class,args);

}

}

```

配置starter需要的bean的配置

```

starterbean.id=test123

starterbean.name=zhaozhen

```

测试类

```

@RunWith(SpringRunner.class)

@SpringBootTest(classes = StarterUseApplication.class)

public class StarterUseTest {

@Autowired

StarterBean starterBean;

@Test

public void starUse(){

System.out.println(starterBean);

}

}

```

测试结果，正常使用