1.自定义启动器starter

 

1. 新建maven工程yahang-spring-boot-starter (starter是一个空JAR包，仅仅作为maven下载jar包的启动器)
2. 新建maven工程yahang-spring-boot-starter-autoconfigure (实际工作的模块)
3. yahang-spring-boot-starter作为一个启动器，设置依赖于yahang-spring-boot-starter-autoconfigure
4.     <dependency>

          <groupId>com.njupt</groupId>

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

          <version>0.0.1-SNAPSHOT</version>

       </dependency>
5. yahang-spring-boot-starter-autoconfigure模块下，设置依赖于spring-boot-starter
6.      <dependency>

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

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

            <version>2.3.0.RELEASE</version>

        </dependency>
7. yahang-spring-boot-starter-autoconfigure模块下，新建包com.njupt,然后新建一个实体类，该实体类为要配置为bean的类
   1. public class MyDataSource {
   2.     public String url;
   3.     public String username;
   4.     public String password;
   5.     public MyDataSource(String url, String username, String password) {
   6.         super();
   7.         this.url = url;
   8.         this.username = username;
   9.         this.password = password;
   10.     }  
   11. }
8. yahang-spring-boot-starter-autoconfigure模块下的com.njupt包下,然后新建一个MyDataSourceProperties类，该实体类为读取yml文件的类，并设置getter,setter方法。
   1. @ConfigurationProperties(prefix = "yahang.mydatasource")
   2. public class MyDataSourceProperties {
   3.     private String url;
   4.     private String username;
   5.     private String password;
9. yahang-spring-boot-starter-autoconfigure模块下的com.njupt包下,然后新建一个MyDataSourceAutoConfigure类，该类使用MyDataSourceProperties对象的属性，new MyDataSource对象，并注入为Bean
   1. @Configuration
   2. @ConditionalOnWebApplication
   3. @EnableConfigurationProperties(MyDataSourceProperties.class)
   4. public class MyDataSourceAutoConfigure {
   5.    
   6.     @Autowired
   7.     private MyDataSourceProperties myDataSourceProperties;
   8.    
   9.     @Bean
   10.     public MyDataSource getDataSource() {
   11.         String url=myDataSourceProperties.getUrl();
   12.         String username=myDataSourceProperties.getUsername();
   13.         String password=myDataSourceProperties.getPassword();
   14.         return new MyDataSource(url, username, password);
   15.     }
   16. }
10. 为了让Springboot加载MyDataSourceAutoConfigure，需要在resources目录下新建META-INF/spring.factories
    1. org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
    2. com.njupt.MyDataSourceAutoConfigure
11. 使用maven install 安装autoconfigure和starter模块。
12. 测试
     
    1. 新建Springboot的web应用，pom文件引入自定义的starter
    2.         <dependency>

                 <groupId>com.njupt</groupId>

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

                 <version>0.0.1-SNAPSHOT</version>

                 </dependency>
    3. 编写application.yml
       1. yahang:
       2.   mydatasource:
       3.     url: localhaost
       4.     username: yahang
       5.     password: 123456
    4. 编写测试代码
       1. @Controller
       2. public class MyController {
       3.    
       4.     @Autowired
       5.     private MyDataSource dataSource;
       6.     @ResponseBody
       7.     @RequestMapping("/test")
       8.     public String getDatasource() {
       9.         return dataSource.url+" : "+ dataSource.username+" : "+dataSource.password;
       10.     }
       11. }
    5. 测试