Java Reflection Introspector

first, explain Introspector introspection, Self-examination.
In the Java.beans package in java, the original text description is:

 
   
  

  
    
   
The Introspector class provides a standard way for tools to learn about the properties, events, and methods supported by a target Java Bean.
 
   
  

Chinese to the effect of

 
   
  

  
    
   
Introspector提供了一种标准的方式作为工具来获取类的属性，时间，方法。
 
   
  

Typically used in reflection, view the internal information of a class. The following is a collection of reflection classes for the space-time change.

  
 

   
  

  
// 类属性缓存，空间换时间
   
  

  
private static final ConcurrentMap, PropertyDescriptor[]> classPropCache =
   
  

  
 new ConcurrentHashMap, PropertyDescriptor[]>(64);
   
  

  
 
   
  

  
/**
   
  

  
 * 获取Bean的属性
   
  

  
 * @param bean
   
  

  
 * @return
   
  

  
 */
   
  

  
private static PropertyDescriptor[] getPropertyDescriptors(Object bean) {
   
  

  
 Class beanClass = bean.getClass();
   
  

  
 PropertyDescriptor[] cachePds = classPropCache.get(beanClass);
   
  

  
 if (null != cachePds) {
   
  

  
 return cachePds;
   
  

  
 }
   
  

  
 try {
   
  

  
 BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
   
  

  
 cachePds = beanInfo.getPropertyDescriptors();
   
  

  
 classPropCache.put(beanClass, cachePds);
   
  

  
 return cachePds;
   
  

  
 } catch (IntrospectionException e) {
   
  

  
 throw new RuntimeException(e);
   
  

  
 }
   
  

  
}
   
  

  
 
   
  

  
/**
   
  

  
 * 获取Bean的属性
   
  

  
 * @param bean bean
   
  

  
 * @param propertyName 属性名
   
  

  
 * @return 属性值
   
  

  
 */
   
  

  
public static Object getProperty(Object bean, String propertyName) {
   
  

  
 PropertyDescriptor[] beanPds = getPropertyDescriptors(bean);
   
  

  
 for (PropertyDescriptor propertyDescriptor : beanPds) {
   
  

  
 if (propertyDescriptor.getName().equals(propertyName)){
   
  

  
 Method readMethod = propertyDescriptor.getReadMethod();
   
  

  
 if (null == readMethod) {
   
  

  
 continue;
   
  

  
 }
   
  

  
 if (!readMethod.isAccessible()) {
   
  

  
 readMethod.setAccessible(true);
   
  

  
 }
   
  

  
 try {
   
  

  
 return readMethod.invoke(bean);
   
  

  
 } catch (Throwable ex) {
   
  

  
 throw new RuntimeException("Could not read property ‘" + propertyName + "‘ from bean", ex);
   
  

  
 }
   
  

  
 }
   
  

  
 }
   
  

  
 return null;
   
  

  
}
   
  

  
 
   
  

  
/**
   
  

  
 * 设置Bean属性
   
  

  
 * @param bean bean
   
  

  
 * @param propertyName 属性名
   
  

  
 * @param value 属性值
   
  

  
 */
   
  

  
public static void setProperty(Object bean, String propertyName, Object value) {
   
  

  
 PropertyDescriptor[] beanPds = getPropertyDescriptors(bean);
   
  

  
 for (PropertyDescriptor propertyDescriptor : beanPds) {
   
  

  
 if (propertyDescriptor.getName().equals(propertyName)){
   
  

  
 Method writeMethod = propertyDescriptor.getWriteMethod();
   
  

  
 if (null == writeMethod) {
   
  

  
 continue;
   
  

  
 }
   
  

  
 if (!writeMethod.isAccessible()) {
   
  

  
 writeMethod.setAccessible(true);
   
  

  
 }
   
  

  
 try {
   
  

  
 writeMethod.invoke(bean, value);
   
  

  
 } catch (Throwable ex) {
   
  

  
 throw new RuntimeException("Could not set property ‘" + propertyName + "‘ to bean", ex);
   
  

  
 }
   
  

  
 }
   
  

  
 }
   
  

  
}
  
 

Java Reflection Introspector