BeanPostProcessor

　　今天学习了一下Spring的BeanPostProcessor接口。

　　该接口作用是：如果我们需要在Spring容器完成Bean的实例化，可以定义一个BeanPostProcessor接口的实现

　　

案例：通过某个参数不同，达到调用同一个接口的不同实现方法的目的，类似适配器模式

创建一个抽象类，作为servicePool 

public abstract class YeweiServicePoolBase<Tp> implements BeanPostProcessor {
	public YeweiServicePoolBase() {  
        super();  
        System.out.println("这是YeweiServicePoolBase实现类构造器！！");          
     }  
	
	
    protected final Map<String, Tp> servicePool = new ConcurrentHashMap<>();

	private final Class<Tp> serviceClass = 
			(Class<Tp>) ((ParameterizedType) YeweiReflectionUtils.
					getOriginalClassWithoutProxy(this).
					getGenericSuperclass()).
					getActualTypeArguments()[0];

    public List<Tp> getAllServices(){
        return new ArrayList<>(servicePool.values());
    }

    public List<String> getAllServiceKeys(){
        return new ArrayList<>(servicePool.keySet());
    }

    public Tp getServiceFromPool(String tp) {
        return servicePool.get(tp);
    }

    public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
    	if (serviceClass.isAssignableFrom(bean.getClass())) {
            Tp theServiceBean = (Tp) bean;
            String theBeanName = getServiceBeanName(theServiceBean);
            if (YeweiStringUtils.isNotEmpty(theBeanName)) {
                servicePool.put(theBeanName, theServiceBean);
            }
        }
        return bean;
    }

    public abstract String getServiceBeanName(Tp theServiceBean);
    
    public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
    	System.out.println("bean处理器：bean创建之后.."+beanName); 
    	return bean;
    }
    
}

　　枚举，作为接口实现类的区分。

public enum ServiceEnum {
	wechat,
	pingpp,
	unionpay,
}

　　适配器接口。

public interface DepositVendorAdapter {
 　　public ServiceEnum getDepositVendorType();
    public void refund() throws Exception;
    public void deposit() throws Exception;
}

　　具体业务接口

public interface DepositVendorService {

　　 public void deposit(String str) throws Exception;

    public void refund() throws Exception;
}

 

业务接口的三个实现：pingpp，wechat，unionpay，

Pingpp：

@Service("pingppPayService")
public class PingppPayServiceImpl implements  DepositVendorAdapter {
	
	@Override
	@Transactional(propagation = Propagation.SUPPORTS)
	public void deposit() throws Exception {
		System.out.println("pingpp pay");
	}

	@Override
	public ServiceEnum getDepositVendorType() {
		// TODO Auto-generated method stub
		return ServiceEnum.pingpp;
	}

	@Override
	public void refund() throws Exception {
		// TODO Auto-generated method stub
		
	}

}

　　UnionPay

@Service("unionPayService")
public class UnionPayServiceImpl implements  DepositVendorAdapter {
	
	@Override
	@Transactional(propagation = Propagation.SUPPORTS)
	public void deposit() throws Exception {
		System.out.println("unionpay pay");
	}

	@Override
	public ServiceEnum getDepositVendorType() {
		// TODO Auto-generated method stub
		return ServiceEnum.unionpay;
	}

	@Override
	public void refund() throws Exception {
		// TODO Auto-generated method stub
		
	}

}

　　wechat

@Service("wechatPayService")
public class WechatPayServiceImpl implements  DepositVendorAdapter {
	
	@Override
	@Transactional(propagation = Propagation.SUPPORTS)
	public void deposit() throws Exception {
		System.out.println("wechat pay");
	}

	@Override
	public ServiceEnum getDepositVendorType() {
		// TODO Auto-generated method stub
		return ServiceEnum.wechat;
	}

	@Override
	public void refund() throws Exception {
		// TODO Auto-generated method stub
		
	}

}

　　适配器接口实现、

@Service("depositVendorService")
public class DepositVendorServiceImpl extends YeweiServicePoolBase<DepositVendorAdapter> implements DepositVendorService {
	
	public DepositVendorServiceImpl() {
	}

	@Override
	public String getServiceBeanName(DepositVendorAdapter theServiceBean) {
		// TODO Auto-generated method stub
		return theServiceBean.getDepositVendorType().name();
	}
	
	

	@Override
	public void deposit(String str) throws Exception {
		// TODO Auto-generated method stub
		DepositVendorAdapter vendorAdapter = this.servicePool.get(str);
        if (vendorAdapter == null) {
            throw new Exception("Vendor Not Defined");
        }
        vendorAdapter.deposit();
	}

	@Override
	public void refund() throws Exception {
		// TODO Auto-generated method stub
		
	}

	
	
	
}

　　

Spring 容器在初始化的时候，会为servicePool 注入 service，类似 {“name”:"service"} 的键值对。

{

wechat=com.yewei.service.deposit.WechatPayServiceImpl@2cb75649,

unionpay=com.yewei.service.deposit.UnionPayServiceImpl@1c0ac42a,

pingpp=com.yewei.service.deposit.PingppPayServiceImpl@74c7a6b2

}

测试代码：

 public static void main(String[] args) throws Exception {
	
    	ApplicationContext ctx=new FileSystemXmlApplicationContext("D:/eclipWorkspace/DepositServicePool/WebContent/WEB-INF/springmvc.xml");  
    	DepositVendorService depositVendorService=(DepositVendorService) ctx.getBean("depositVendorService");  
    	
    	depositVendorService.deposit("wechat");
    	depositVendorService.deposit("pingpp");
    	depositVendorService.deposit("unionpay");
    }

　　打印：

wechat pay
pingpp pay
unionpay pay