spring动态注入

使用场景:jar提供的接口回调,仅Service名字不同,每次需要新写一个实现类,太过累赘,可以通过重复注入同一个实现,仅改变名字,示例如下,支持注入Bean和具体值

package com.yunjin.redis;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.stereotype.Component;

public class Spring {
	public static void main(String[] args) throws Exception {
		ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:" + Spring.class.getSimpleName() + ".xml");
		Person my;
		my = (Person) context.getBean("person1");
		my.my();
		my = (Person) context.getBean("person2");
		my.my();
		context.close();
	}
}

@Component
class Dept {
	public void dept() {
		System.out.println("dept");
	}
}

@Component
class Salary {
	public void salary() {
		System.out.println("salary");
	}
}

class Person {
	private Dept dept;
	private Salary salary;

	private String name;

	public void my() {
		System.out.println("my" + "-" + name + "-");
		dept.dept();
		salary.salary();
	}

	public Salary getSalary() {
		return salary;
	}

	public void setSalary(Salary salary) {
		this.salary = salary;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Dept getDept() {
		return dept;
	}

	public void setDept(Dept dept) {
		this.dept = dept;
	}
}

@Component
class PersonBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		DefaultListableBeanFactory defaultListableBeanFactory = (DefaultListableBeanFactory) beanFactory;
		BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.genericBeanDefinition(Person.class);
		String beanName = beanFactory.getBeansOfType(Dept.class).keySet().stream().findFirst().get();
		beanDefinitionBuilder.addPropertyReference("dept", beanName);
		beanDefinitionBuilder.addPropertyValue("salary", beanFactory.getBean(Salary.class));
		beanDefinitionBuilder.addPropertyValue("name", "哈哈哈22");
		BeanDefinition personManagerBeanDefinition = beanDefinitionBuilder.getRawBeanDefinition();
		defaultListableBeanFactory.registerBeanDefinition("person1", personManagerBeanDefinition);
		defaultListableBeanFactory.registerBeanDefinition("person2", personManagerBeanDefinition);
	}
}