Spring之动态注册bean的实现方法

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Spring之动态注册bean

什么场景下，需要主动向Spring容器注册bean呢？

如我之前做个的一个支持扫表的基础平台，使用者只需要添加基础配置 + Groovy任务，就可以丢到这个平台上面来运行了，而这个基础平台是一直都在运行的，所以在新来任务时，最直观需要注册的就是 DataSource 数据源这个bean了，那么可以怎么玩？

I. 主动注册Bean支持

借助BeanDefinition来实现bean的定义，从最终的使用来看，代码比较少，几行而已

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);
}

测试如下

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);
  }

  @ToString
  public static class InrSer {
    private String name;
    private Integer uid;

    @Autowired
    private 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);
  }
}

输出如下