Spring之動態注冊bean

什么場景下，需要主動向Spring容器注冊bean呢？

如我之前做個的一個支持掃表的基礎平臺，使用者只需要添加基礎配置 + Groovy任務，就可以丟到這個平臺上面來運行了，而這個基礎平臺是一直都在運行的，所以在新來任務時，最直觀需要注冊的就是 DataSource 數據源這個bean了，那么可以怎么玩？

I. 主動注冊Bean支持

借助BeanDefinition來實現bean的定義，從最終的使用來看，代碼比較少，幾行而已

public <T> T registerBean(String name, Class<T> clazz, Object... args) {BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(clazz);if (args.length > 0) {for (Object arg : args) {beanDefinitionBuilder.addConstructorArgValue(arg);}}BeanDefinition beanDefinition = beanDefinitionBuilder.getRawBeanDefinition();BeanDefinitionRegistry beanFactory = (BeanDefinitionRegistry) applicationContext.getBeanFactory();beanFactory.registerBeanDefinition(name, beanDefinition);return applicationContext.getBean(name, clazz);
}
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測試如下

import com.github.hui.story.quickstory.server.VisitService;
import lombok.ToString;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.stereotype.Component;@Component
public class BeanHolder {private final ConfigurableApplicationContext applicationContext;public BeanHolder(ConfigurableApplicationContext applicationContext) {this.applicationContext = applicationContext;initSer();}public void initSer() {InrSer ser = registerBean("test", InrSer.class);ser.name = "一灰";ser.uid = 22;System.out.println(ser);InrSer ser2 = registerBean("test2", InrSer.class, "一灰灰Blog", 20);System.out.println(ser2);}@ToStringpublic static class InrSer {private String name;private Integer uid;@Autowiredprivate VisitService visitService;public InrSer() {}public InrSer(String name, Integer uid) {this.name = name;this.uid = uid;}}private <T> T registerBean(String name, Class<T> clazz, Object... args) {BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(clazz);if (args.length > 0) {for (Object arg : args) {beanDefinitionBuilder.addConstructorArgValue(arg);}}BeanDefinition beanDefinition = beanDefinitionBuilder.getRawBeanDefinition();BeanDefinitionRegistry beanFactory = (BeanDefinitionRegistry) applicationContext.getBeanFactory();beanFactory.registerBeanDefinition(name, beanDefinition);return applicationContext.getBean(name, clazz);}
}
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