1、创建spring boot项目，命名为mymsgstarter-spring-boot-starter。项目结构见图。其中MsgProperties、MsgAutoConfiguration、MsgService分别为配置属性类、配置类、和服务类。
2、配置属性类MsgProperties，使用@ConfigurationProperties(prefix = "com.mymsg")声明，并设置prefix前缀。定义属性类中的属性msg。@ConfigurationProperties(prefix = "com.mymsg")public class MsgProperties { private String msg = "default msg"; public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; }}
3、服务类MsgService，定义msg属性，此类为普通的service，提供给其他服务调用。public class MsgService { private String msg; public MsgService(String msg) { this.msg = msg; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; }}
4、自动配置类MsgAutoConfiguration。注入配置属性类，并把配置属性类中的msg值赋予给service中msg。@Configuration@EnableConfigurationProperties(MsgProperties.class)@ConditionalOnClass(MsgService.class)public class MsgAutoConfiguration { @Autowired private MsgProperties msgProperties; @Bean @ConditionalOnMissingBean @ConditionalOnProperty(prefix = "com.mymsg",value = "enabled",matchIfMissing = true) public MsgService msgService() { return new MsgService(msgProperties.getMsg()); }}
5、注册自动配置类spring.factoriesorg.springframework.data.repository.core.support.RepositoryFactorySupport=com.mypro.springboot.mymsgstarterspringbootstarter.MsgAutoConfiguration
6、install。在idea中的maven projects窗口，找到项目，lifecycle下选中install并执行，即可install jar包至本地maven仓库。注意，maven setting中，MAVEN-Runner下的jdk要选择1.8，否则install报无效字符-paramters的异常。另，pom.xml中的<build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build>要去掉，否则项目jar包的目录不合规范
7、新创建项目，在pom.xml中引入自定义starter的依赖，更新依赖包<dependency> <groupId>com.mypro.springboot</groupId> <artifactId>mymsgstarter-spring-boot-starter</artifactId> <version>0.0.1-SNAPSHOT</version></dependency>
8、编写测试类。@RunWith(SpringRunner.class)@SpringBootApplication@ComponentScan(basePackages = {"com.mypro","com.myproject"})public class MyMsgStarterTest { @Autowired private MsgService msgService; @Test public void test() { System.out.println(msgService.getMsg()); }}
9、测试结果1配置属性类MsgProperties的msg的默认值为default msg，测试结果输出为default msg。
10、测试结果2在application.properties中设置msg的值，com.mymsg.msg=hello world，测试结果输出为hello world
