扩展 properties 注解-优快云博客

本文链接：https://blog.youkuaiyun.com/cqskyeagle/article/details/83801661

本文介绍了一种通过自定义注解实现属性注入的方法。该方法包括创建注解、设计注解处理类并实现BeanPostProcessor接口，以及如何在Spring配置文件中配置和使用该注解。此方案适用于特定类型的属性注入场景。

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1：创建注解

/**
 * 
 * @author ZhangKaiTao
 *
 */
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface Properties {
	String name();
}

2：扩展

/**
 * 
 * @author ZhangKaiTao
 *
 */
public class AnnotationBeanPostProcessor extends PropertyPlaceholderConfigurer
		implements BeanPostProcessor, InitializingBean {

	private static transient Log logger = LogFactory
			.getLog(AnnotationBeanPostProcessor.class);

	private java.util.Properties pros;

	@SuppressWarnings("unchecked")
	private Class[] enableClassList = { String.class };

	@SuppressWarnings("unchecked")
	public void setEnableClassList(Class[] enableClassList) {
		this.enableClassList = enableClassList;
	}

	public Object postProcessAfterInitialization(Object bean, String beanName)
			throws BeansException {

		Field[] fields = bean.getClass().getDeclaredFields();

		for (Field field : fields) {
			 			if (field.isAnnotationPresent(Properties.class)) {
				if (filterType(field.getType().toString())) {
					Properties p = field.getAnnotation(Properties.class);
					try {
						ReflectionUtils.makeAccessible(field);
						field.set(bean, pros.getProperty(p.name()));
					} catch (Exception e) {
						logger.error(" --- ", e);
					}
				}
			}
		}

		return bean;
	}

	@SuppressWarnings("unchecked")
	private boolean filterType(String type) {

		if (type != null) {
			for (Class c : enableClassList) {
				if (c.toString().equals(type)) {
					return true;
				}
			}
			return false;
		} else {
			return true;
		}
	}

	public Object postProcessBeforeInitialization(Object bean, String beanName)
			throws BeansException {
		return bean;
	}

	public void afterPropertiesSet() throws Exception {
		pros = mergeProperties();
	}
}

3：配置

<bean id="propertyConfigurer" class="withub.system.versioncontrol.com.AnnotationBeanPostProcessor" scope="singleton">
		<property name="locations">
			<list>
				<value>classpath:db.properties</value>
			</list>
		</property>
	</bean>

4：使用

@Properties(name="fydm")
	private String fydm;