【SpringBoot教程 自定义Starter】3. 自定义@Enabel
前言
SpringBoot中提供了很多Enable开头的注解，这些注解都是用于动态启用某些功能的。而其底层原理是使用@Import注解导入一些配置类，实现Bean的动态加载。
如：@EnableAsync、@EnableScheduling
自定义starter实战
需求：编写一个starter连接mysql的功能。使用者引入依赖，只有使用@EnableJdbc才能连上数据库。
项目结构如下
- enable-spring-boot-starter（自定义的starter SPI机制）
- test-starter（使用 starter）
创建enable-spring-boot-starter项目
pom.xml
<parent><groupId>org.springframework.bootgroupId><artifactId>spring-boot-starter-parentartifactId><version>2.4.2version>
parent>
<modelVersion>4.0.0modelVersion>
<groupId>com.terrygroupId>
<artifactId>enable-spring-boot-starterartifactId>
<version>1.0-SNAPSHOTversion><properties><maven.compiler.source>8maven.compiler.source><maven.compiler.target>8maven.compiler.target>properties><dependencies><dependency><groupId>org.springframework.bootgroupId><artifactId>spring-boot-configuration-processorartifactId>dependency><dependency><groupId>org.springframeworkgroupId><artifactId>spring-jdbcartifactId><version>5.3.3version>dependency><dependency><groupId>com.zaxxergroupId><artifactId>HikariCPartifactId><version>3.4.5version>dependency><dependency><groupId>mysqlgroupId><artifactId>mysql-connector-javaartifactId>dependency>dependencies>
创建jdbc 自动装配类
import com.zaxxer.hikari.HikariDataSource;
import lombok.extern.java.Log;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.core.JdbcTemplate;/*** jdbc 自动装配* @author terry* @version 1.0* @date 2022/6/5 11:48*/
//@Configuration
@Log
public class JdbcAutoConfiguration {@Bean// mysql属性自动注入到HikariDataSource中// @ConfigurationProperties(prefix = "mysql")public HikariDataSource dataSource(){log.info("配置hikar1...");return new HikariDataSource();}@Beanpublic JdbcTemplate jdbcTemplate(HikariDataSource dataSource){log.info("配置JdbcTemplate..." + dataSource.getJdbcUrl());return new JdbcTemplate(dataSource);}
}
创建@EnableJdbc注解
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.context.annotation.Import;@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Import({JdbcAutoConfiguration.class})
@Documented
public @interface EnableJdbc {}
创建test-starter项目
故意给包名取得不一样，来验证是否能自动装配：
enable-spring-boot-starter包名：com.terry
test-starter包名：com.terrybg
pom.xml
<parent><groupId>org.springframework.bootgroupId><artifactId>spring-boot-starter-parentartifactId><version>2.4.2version>
parent><modelVersion>4.0.0modelVersion><groupId>com.terrybggroupId><artifactId>test-starterartifactId><properties><maven.compiler.source>8maven.compiler.source><maven.compiler.target>8maven.compiler.target>properties><dependencies><dependency><groupId>com.terrygroupId><artifactId>enable-spring-boot-starterartifactId><version>1.0-SNAPSHOTversion>dependency>dependencies>
启动类
/*** 自定义starter 使用* @author terry* @version 1.0* @date 2022/6/5 14:04*/
@SpringBootApplication
@EnableJdbc
public class App {public static void main(String[] args) {SpringApplication.run(App.class);}
}
application.yml
mysql:driverClassName: com.mysql.cj.jdbc.DriverjdbcUrl: jdbc:mysql://192.168.126.156:3306/testusername: rootpassword: 123456
成功自动装配
Initializing ExecutorService 'applicationTaskExecutor'
2022-06-05 15:57:49.089 INFO 41568 --- [ main] com.terry.config.JdbcAutoConfiguration : 配置hikar...
2022-06-05 15:57:49.109 INFO 41568 --- [ main] com.terry.config.JdbcAutoConfiguration : 配置JdbcTemplate...jdbc:mysql://192.168.126.156:3306/test
2022-06-05 15:57:49.173 INFO 41568 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2022-06-05 15:57:49.181 INFO 41568 --- [ main] com.terrybg.App : Started App in 1.82 seconds (JVM running for 2.894)
启动类注释@EnableJdbc
import com.terry.config.EnableJdbc;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;/*** 自定义starter 使用* @author terry* @version 1.0* @date 2022/6/5 14:04*/
@SpringBootApplication
// @EnableJdbc
public class App {public static void main(String[] args) {SpringApplication.run(App.class);}
}
测试运行成功：(没有自动装配)
2022-06-05 15:56:05.855 INFO 14280 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2022-06-05 15:56:05.864 INFO 14280 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2022-06-05 15:56:05.864 INFO 14280 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.41]
2022-06-05 15:56:05.943 INFO 14280 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2022-06-05 15:56:05.943 INFO 14280 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 808 ms
2022-06-05 15:56:06.173 INFO 14280 --- [ main] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2022-06-05 15:56:06.365 INFO 14280 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2022-06-05 15:56:06.375 INFO 14280 --- [ main] com.terrybg.App : Started App in 1.735 seconds (JVM running for 2.927)本文来自互联网用户投稿，文章观点仅代表作者本人，不代表本站立场，不承担相关法律责任。如若转载，请注明出处。 如若内容造成侵权/违法违规/事实不符，请点击【内容举报】进行投诉反馈！