[Java知识库]spring boot 自定义起步依赖

需求：

我们在一个项目中添加自定义起步依赖，无序额外配置即可使用jedis（开箱即用）

首先我们在mystarter自定义起步依赖model中加入

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
            <version>2.5.4</version>
        </dependency>
        <!--加入jedis坐标-->
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>2.6.0</version>
        </dependency>

然后新建一个类

package com.demo.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import redis.clients.jedis.Jedis;

@Configuration
public class JedisAutoConfiguration {

    @Bean
    public Jedis jedis(){

        return new Jedis("localhost",6379);
    }

}

在resources里面添加这个文件META-INF/spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.demo.config.JedisAutoConfiguration

以上自定义起步依赖就好了

然后我们在另一个model中测试

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!--加入我们的自定义starter（起步依赖）-->
        <dependency>
            <groupId>org.example</groupId>
            <artifactId>mystarter</artifactId>
            <version>1.0-SNAPSHOT</version>
        </dependency>

/*
* @SpringBootApplication
* 这个注解里面有@EnableAutoConfiguration又通过
* @Import(AutoConfigurationImportSelector.class)引入了AutoConfigurationImportSelector.class
*
* 所以会自动找META-INF/spring.factories
* */
@SpringBootApplication
public class Demo1Application {

    public static void main(String[] args) {
        ConfigurableApplicationContext applicationContext = SpringApplication.run(Demo1Application.class, args);
        Jedis bean = applicationContext.getBean(Jedis.class);
        System.out.println(bean);
    }

}

--------------------------------------------------------

通过以上就完成了自定义起步依赖

优化一下配置

在自定义model中加入

package com.demo.config;

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

import java.io.Serializable;


@ConfigurationProperties(prefix = "redis")
public class RedisProperties implements Serializable {
    private String host="localhost";
    private Integer port=6379;

    public String getHost() {
        return host;
    }

    public void setHost(String host) {
        this.host = host;
    }

    public Integer getPort() {
        return port;
    }

    public void setPort(Integer port) {
        this.port = port;
    }
}

修改JedisAutoConfiguration类

package com.demo.config;

import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import redis.clients.jedis.Jedis;

@Configuration
/*
 * 启用pojo,映射到yml文件中，并且交给spring容器进行管理
 * */
@EnableConfigurationProperties(RedisProperties.class)
@ConditionalOnClass(Jedis.class)//当类路径下又Jedis.class这个整个注解配置才会生效
public class JedisAutoConfiguration {

    @Bean
    /*如果别人在自己代码中配置了就不要把这个bean加入容器*/
    @ConditionalOnMissingBean(name = "jedis")
    public Jedis jedis(RedisProperties redisProperties){

        return new Jedis(redisProperties.getHost(), redisProperties.getPort());
    }

}

----

在测试的model中application.yaml文件中配置

redis:
  host: localhost
  port: 6379

这样就不用把redis的ip和端口号写死在自定义起步依赖中了