springboot自动配置自定义的Starter

￡神魔★判官ぃ 2022-02-20 15:49 252阅读 0赞

# springboot自动配置自定义的Starter #

### 文章目录 ###

*  springboot自动配置自定义的Starter
 *   *   *  1.自动配置原理
         *  2.自定义Starter

代码示例下载： [https://github.com/2010yhh/springBoot-demos/tree/master/springboot-user-starter][https_github.com_2010yhh_springBoot-demos_tree_master_springboot-user-starter]

### 1.自动配置原理 ###

1.  @SpringBootApplication
2.  @EnableAutoConfiguration
3.  @Import(EnableAutoConfigurationImportSelector.class)(//AutoConfigurationImportSelector)
4.  EnableAutoConfigurationImportSelector（//AutoConfigurationImportSelector）使用SpringFactoriesLoader.loadFactoryNames方法来扫描具有MEAT-INF/spring.factories文件的jar包（SpringBoot 在启动时会去依赖的starter包中寻找 `resources/META-INF/spring.factories`文件，然后根据文件中配置的Jar包去扫描项目所依赖的Jar包）
5.  根据 `spring.factories`配置加载`AutoConfigure`类;根据 `@Conditional`等注解的条件，进行自动配置并将Bean注入Spring 容器中。

### 2.自定义Starter ###

1.新建springboot工程（Configuration Processor）

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 1]  
会自动引入需要的pom依赖：

<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>

2.定义自动配置的属性类

@ConfigurationProperties("com.ctg.test.user")
    public class UserProperties {
        private String userName;
        private String passWord;
       ......
    }

3.定义自动配置服务类

public class UserService {
        private String userName;
        private String passWord;
        public UserService(String userName,String passWord) {
            this.userName =userName;
            this.passWord =passWord;
        }
        public void print(){
            System.out.println("userName:"+userName);
            System.out.println("passWord:"+passWord);
        }
    }

4.定义AutoConfigure类

/**
     * @ConditionalOnBean:当容器中有指定的Bean的条件下
     * @ConditionalOnClass：当类路径下有指定的类的条件下
     * @ConditionalOnExpression:基于SpEL表达式作为判断条件
     * @ConditionalOnJava:基于JVM版本作为判断条件
     * @ConditionalOnJndi:在JNDI存在的条件下查找指定的位置
     * @ConditionalOnMissingBean:当容器中没有指定Bean的情况下
     * @ConditionalOnMissingClass:当类路径下没有指定的类的条件下
     * @ConditionalOnNotWebApplication:当前项目不是Web项目的条件下
     * @ConditionalOnProperty:指定的属性是否有指定的值
     * @ConditionalOnResource:类路径下是否有指定的资源
     * @ConditionalOnSingleCandidate:当指定的Bean在容器中只有一个，或者在有多个Bean的情况下，用来指定首选的Bean @ConditionalOnWebApplication:当前项目是Web项目的条件下
     */
    @Configuration
    @ConditionalOnClass(UserService.class)
    @EnableConfigurationProperties(UserProperties.class)
    public class UserAutoConfigure {
        @Autowired
        UserProperties userProperties;
        @Bean
        @ConditionalOnMissingBean
        @ConditionalOnProperty(prefix = "com.ctg.test.user", value = "enabled", havingValue = "true")
        UserService userService (){
            return new UserService(userProperties.getUserName(),userProperties.getPassWord());
        }
    }

5.spring.factories文件

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
      com.ctg.test.springbootuserstarter.UserAutoConfigure

最终工程目录;  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 2]  
6.打包,随便打包方式  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 3]  
生成：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 4]

7.测试  
测试工程配置文件：

#定义自动配置的属性
    com:
      ctg:
        test:
          user:
            user-name: zyq
            pass-word: 123456
            enabled: true

测试工程pom引入：

<dependency>
                <groupId>com.ctg.test</groupId>
                <artifactId>user-springboot-starter</artifactId>
                <version>1.0.0-SNAPSHOT</version>
            </dependency>

测试示例：

@RunWith(SpringRunner.class)
    @SpringBootTest
    public class SpringbootStarterTestApplicationTests {
        @Autowired
        UserService userService;
        @Test
        public void contextLoads() {
        }
        @Test
        public void starterTest() {
            userService.print();
        }
    }

debug发现自定义的Starter已经注册进来  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3loaHloaHloaHloaA_size_16_color_FFFFFF_t_70 5]  
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[https_github.com_2010yhh_springBoot-demos_tree_master_springboot-user-starter]: https://github.com/2010yhh/springBoot-demos/tree/master/springboot-user-starter
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