带你了解@ConfigurationProperties的实现原理

myconfig.name=test
myconfig.age=22
myconfig.desc=这是我的测试描述

@Component
@ConfigurationProperties(prefix = "myconfig")
public class MyConfig {
private String name;
private Integer age;
private String desc;
  //get/set 略
  @Override
public String toString() {
	return "MyConfig [name=" + name + ", age=" + age + ", desc=" + desc + "]";
}
}

public static void main(String[] args) throws Exception {
	SpringApplication springApplication = new SpringApplication(Application.class);
	// 非web环境
	springApplication.setWebEnvironment(false);
	ConfigurableApplicationContext application = springApplication.run(args);

	MyConfig config = application.getBean(MyConfig.class);
	log.info(config.toString());
	application.close();
}

com.cml.chat.lesson.lesson3.Application - MyConfig [name=test, age=22, desc=这是我的测试描述]

public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProcessor,
	BeanFactoryAware, EnvironmentAware, ApplicationContextAware, InitializingBean,
	DisposableBean, ApplicationListener<ContextRefreshedEvent>, PriorityOrdered 

@Override
public Object postProcessBeforeInitialization(Object bean, String beanName)
		throws BeansException {
	//直接通过查找添加了ConfigurationProperties注解的的类
	ConfigurationProperties annotation = AnnotationUtils
			.findAnnotation(bean.getClass(), ConfigurationProperties.class);
	if (annotation != null) {
		postProcessBeforeInitialization(bean, beanName, annotation);
	}
	//查找使用工厂bean中是否有ConfigurationProperties注解
	annotation = this.beans.findFactoryAnnotation(beanName,
			ConfigurationProperties.class);
	if (annotation != null) {
		postProcessBeforeInitialization(bean, beanName, annotation);
	}
	return bean;
}

private void postProcessBeforeInitialization(Object bean, String beanName,
		ConfigurationProperties annotation) {
	Object target = bean;
	PropertiesConfigurationFactory<Object> factory = new PropertiesConfigurationFactory<Object>(
			target);
	factory.setPropertySources(this.propertySources);
	factory.setValidator(determineValidator(bean));
	// If no explicit conversion service is provided we add one so that (at least)
	// comma-separated arrays of convertibles can be bound automatically
	factory.setConversionService(this.conversionService == null
			&#63; getDefaultConversionService() : this.conversionService);
	if (annotation != null) {
		factory.setIgnoreInvalidFields(annotation.ignoreInvalidFields());
		factory.setIgnoreUnknownFields(annotation.ignoreUnknownFields());
		factory.setExceptionIfInvalid(annotation.exceptionIfInvalid());
		factory.setIgnoreNestedProperties(annotation.ignoreNestedProperties());
		if (StringUtils.hasLength(annotation.prefix())) {
			factory.setTargetName(annotation.prefix());
		}
	}
	try {
		factory.bindPropertiesToTarget();
	}
	catch (Exception ex) {
		String targetClass = ClassUtils.getShortName(target.getClass());
		throw new BeanCreationException(beanName, "Could not bind properties to "
				+ targetClass + " (" + getAnnotationDetails(annotation) + ")", ex);
	}
}

public class ConfigurationBeanFactoryMetaData implements BeanFactoryPostProcessor {

private ConfigurableListableBeanFactory beanFactory;

private Map<String, MetaData> beans = new HashMap<String, MetaData>();

@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
		throws BeansException {
	this.beanFactory = beanFactory;
 //迭代所有的bean定义，找出那些是工厂bean的对象添加到beans中
	for (String name : beanFactory.getBeanDefinitionNames()) {
		BeanDefinition definition = beanFactory.getBeanDefinition(name);
		String method = definition.getFactoryMethodName();
		String bean = definition.getFactoryBeanName();
		if (method != null && bean != null) {
			this.beans.put(name, new MetaData(bean, method));
		}
	}
}

public <A extends Annotation> Map<String, Object> getBeansWithFactoryAnnotation(
		Class<A> type) {
	Map<String, Object> result = new HashMap<String, Object>();
	for (String name : this.beans.keySet()) {
		if (findFactoryAnnotation(name, type) != null) {
			result.put(name, this.beanFactory.getBean(name));
		}
	}
	return result;
}

public <A extends Annotation> A findFactoryAnnotation(String beanName,
		Class<A> type) {
	Method method = findFactoryMethod(beanName);
	return (method == null &#63; null : AnnotationUtils.findAnnotation(method, type));
}

//略...
	
private static class MetaData {
	private String bean;
	private String method;
  //构造方法和其他方法略...
}

}

private void postProcessBeforeInitialization(Object bean, String beanName,
		ConfigurationProperties annotation) {
	Object target = bean;
	PropertiesConfigurationFactory<Object> factory = new PropertiesConfigurationFactory<Object>(
			target);
	//重点，这里设置数据来源
	factory.setPropertySources(this.propertySources);
	factory.setValidator(determineValidator(bean));
	//设置转换器
	factory.setConversionService(this.conversionService == null
			&#63; getDefaultConversionService() : this.conversionService);
	if (annotation != null) {
	//将annotation中配置的属性配置到factory中
	}
	try {
	  //这里是核心，绑定属性值到对象中
		factory.bindPropertiesToTarget();
	}
	catch (Exception ex) {
	//抛出异常
	}
}

private void doBindPropertiesToTarget() throws BindException {
	RelaxedDataBinder dataBinder 
  //略...
  //1、获取bean中所有的属性名称
  Set<String> names = getNames(relaxedTargetNames);
  //2、将属性名称和前缀转换为配置文件的key值
  PropertyValues propertyValues = getPropertySourcesPropertyValues(names,relaxedTargetNames);
  //3、通过上面两个步骤找到的属性从配置文件中获取数据通过反射注入到bean中
	dataBinder.bind(propertyValues);
	//数据校验
	if (this.validator != null) {
		dataBinder.validate();
	}
	//判断数据绑定过程中是否有错误
	checkForBindingErrors(dataBinder);
}

public void bind(PropertyValues pvs) {
	MutablePropertyValues mpvs = (pvs instanceof MutablePropertyValues) ?
			(MutablePropertyValues) pvs : new MutablePropertyValues(pvs);
	doBind(mpvs);
}
protected void doBind(MutablePropertyValues mpvs) {
	checkAllowedFields(mpvs);
	checkRequiredFields(mpvs);
	//进行赋值
	applyPropertyValues(mpvs);
}
protected void applyPropertyValues(MutablePropertyValues mpvs) {
	try {
		// Bind request parameters onto target object.
		getPropertyAccessor().setPropertyValues(mpvs, isIgnoreUnknownFields(), isIgnoreInvalidFields());
	}
	catch (PropertyBatchUpdateException ex) {
		// Use bind error processor to create FieldErrors.
		for (PropertyAccessException pae : ex.getPropertyAccessExceptions()) {
			getBindingErrorProcessor().processPropertyAccessException(pae, getInternalBindingResult());
		}
	}
}