SpringBoot动态创建Bean

àì夳堔傛蜴生んèń 2022-08-22 00:24 187阅读 0赞

SpringBoot测试版本：1.3.4.RELEASE

参考代码如下：

package com.spring.configuration;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.beans.factory.support.BeanDefinitionBuilder;
    import org.springframework.beans.factory.support.DefaultListableBeanFactory;
    import org.springframework.boot.autoconfigure.condition.ConditionalOnExpression;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.ConfigurableApplicationContext;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.jdbc.core.JdbcTemplate;
    
    @Configuration
    /**
     * 这里的conditional是一个可选条件，表示当这个表达式为true的时候，才动态创建bean
     */
    @ConditionalOnExpression("${my.configuration.enabled}")
    public class DynamicConfiguration
    {
    	@Autowired
    	private ApplicationContext applicationContext;
    	
    	/**
    	 * 这个方法返回Runnable只是一个幌子，最重要的是执行方法里面的代码
    	 */
    	@Bean
    	public Runnable dynamicConfiguration() throws Exception
    	{
    		ConfigurableApplicationContext context = (ConfigurableApplicationContext)applicationContext;
    		DefaultListableBeanFactory beanFactory = (DefaultListableBeanFactory)context.getBeanFactory();
    		
    		BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(UserService.class);
    		/**
    		 * 设置属性
    		 */
    		beanDefinitionBuilder.addPropertyValue("name", "myConfigure");
    		beanDefinitionBuilder.addPropertyValue("jdbcTemplate", applicationContext.getBean(JdbcTemplate.class));
    		
    		/**
    		 * 注册到spring容器中
    		 */
    		beanFactory.registerBeanDefinition("userService", beanDefinitionBuilder.getBeanDefinition());
    		return null;
    	}
    }
    class UserService
    {
    	private String name;
    	private JdbcTemplate jdbcTemplate;
    	public String getName()
    	{
    		return name;
    	}
    	public void setName(String name)
    	{
    		this.name = name;
    	}
    	public JdbcTemplate getJdbcTemplate()
    	{
    		return jdbcTemplate;
    	}
    	public void setJdbcTemplate(JdbcTemplate jdbcTemplate)
    	{
    		this.jdbcTemplate = jdbcTemplate;
    	}
    }

之后，就可以使用如下方式获取对象了  
applicationContext.getBean(UserService.class);  
applicationContext.getBean("userService", UserService.class)