SpringBoot通过yml等配置文件动态生成多个Bean

demo说明

通过在yaml等配置文件中配置map，然后根据map生成多个Bean。

比如如下配置：就应该生成2个Bean。

最后效果：应该在Spring容器中生成name=key1, name=key2的两个Bean。

配置文件对应的类

package test.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;

import java.util.Map;

/**
 * @author wenei
 * @date 2022-01-06 20:00
 */
@ConfigurationProperties("test")
@Data
public class BeanProperties {

    private Map<String, String> mapping;
}

Config

注入到Spring容器中的Bean类型。

package test.config;

import lombok.Data;

/**
 * @author wenei
 * @date 2022-01-06 20:00
 */
@Data
public class Config {

    private String value;
}

核心处理类

通过@Import导入ImportBeanDefinitionRegistrar的实现类；

同时实现EnvironmentAware接口，注入Environment，然后通过Binder将Environment配置绑定出一个配置类；

最后通过配置类动态绑定BeanDefinition到容器中。

(为什么不能使用Autowired方式注入BeanProperties？我的理解：因为这还只是Spring容器的加入BeanDefinition的阶段，所有的BeanDefinition还没有实例化成Bean)

package test.config;

import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.context.EnvironmentAware;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Import;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.env.Environment;
import org.springframework.core.type.AnnotationMetadata;

import java.util.Map;
import java.util.Objects;

/**
 * @author wenei
 * @date 2022-01-06 20:00
 */
@Configuration
@EnableConfigurationProperties(BeanProperties.class)
@Import(AppConfig.ImportConfig.class)
public class AppConfig {


    public static class ImportConfig implements ImportBeanDefinitionRegistrar, EnvironmentAware {

        private BeanProperties beanProperties;

        @Override
        public void registerBeanDefinitions(AnnotationMetadata annotationMetadata, BeanDefinitionRegistry beanDefinitionRegistry) {
            for (Map.Entry<String, String> entry : beanProperties.getMapping().entrySet()) {
                // 注册bean
                RootBeanDefinition beanDefinition = new RootBeanDefinition();
                beanDefinition.setBeanClass(Config.class);
                MutablePropertyValues values = new MutablePropertyValues();
                values.addPropertyValue("value", entry.getValue());
                beanDefinition.setPropertyValues(values);
                beanDefinitionRegistry.registerBeanDefinition(entry.getKey(), beanDefinition);
            }
        }

        @Override
        public void setEnvironment(Environment environment) {
            // 通过Binder将environment中的值转成对象
            beanProperties = Binder.get(environment).bind(getPropertiesPrefix(BeanProperties.class), BeanProperties.class).get();
        }

        private String getPropertiesPrefix(Class<?> tClass) {
            return Objects.requireNonNull(AnnotationUtils.getAnnotation(tClass, ConfigurationProperties.class)).prefix();
        }
    }
}

最后使用

package test.api;

import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import test.config.BeanProperties;
import test.config.Config;

import javax.annotation.Resource;

/**
 * @author wenei
 * @date 2022-01-06 20:02
 */
@RestController
@RequiredArgsConstructor
public class ConfigApi {

    private final BeanProperties beanProperties;

    @Resource(name = "key1")
    private Config key1Config;

    @GetMapping("/config")
    public String config() {
        return beanProperties.getMapping().toString();
    }

    @GetMapping("key1")
    public String key1() {
        return key1Config.getValue();
    }
}