Java反射 Introspector

一、解释

Introspector  内省，自我检查。

位于java中的java.beans包中，其原文说明文为：

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

中文大意为

1. 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。

通常用在反射中，查看类的内部信息。

以下为收集到的一个，空间换时间的反射类。

1. // 类属性缓存，空间换时间
2. private static final ConcurrentMap, PropertyDescriptor[]> classPropCache =
3. new ConcurrentHashMap, PropertyDescriptor[]>(64);
5. /**
6. * 获取Bean的属性
7. * @param bean
8. * @return
9. */
10. private static PropertyDescriptor[] getPropertyDescriptors(Object bean) {
11. Class beanClass = bean.getClass();
12. PropertyDescriptor[] cachePds = classPropCache.get(beanClass);
13. if (null != cachePds) {
14. return cachePds;
15. }
16. try {
17. BeanInfo beanInfo = Introspector.getBeanInfo(beanClass);
18. cachePds = beanInfo.getPropertyDescriptors();
19. classPropCache.put(beanClass, cachePds);
20. return cachePds;
21. } catch (IntrospectionException e) {
22. throw new RuntimeException(e);
23. }
24. }
26. /**
27. * 获取Bean的属性
28. * @param bean bean
29. * @param propertyName 属性名
30. * @return 属性值
31. */
32. public static Object getProperty(Object bean, String propertyName) {
33. PropertyDescriptor[] beanPds = getPropertyDescriptors(bean);
34. for (PropertyDescriptor propertyDescriptor : beanPds) {
35. if (propertyDescriptor.getName().equals(propertyName)){
36. Method readMethod = propertyDescriptor.getReadMethod();
37. if (null == readMethod) {
38. continue;
39. }
40. if (!readMethod.isAccessible()) {
41. readMethod.setAccessible(true);
42. }
43. try {
44. return readMethod.invoke(bean);
45. } catch (Throwable ex) {
46. throw new RuntimeException("Could not read property '" + propertyName + "' from bean", ex);
47. }
48. }
49. }
50. return null;
51. }
53. /**
54. * 设置Bean属性
55. * @param bean bean
56. * @param propertyName 属性名
57. * @param value 属性值
58. */
59. public static void setProperty(Object bean, String propertyName, Object value) {
60. PropertyDescriptor[] beanPds = getPropertyDescriptors(bean);
61. for (PropertyDescriptor propertyDescriptor : beanPds) {
62. if (propertyDescriptor.getName().equals(propertyName)){
63. Method writeMethod = propertyDescriptor.getWriteMethod();
64. if (null == writeMethod) {
65. continue;
66. }
67. if (!writeMethod.isAccessible()) {
68. writeMethod.setAccessible(true);
69. }
70. try {
71. writeMethod.invoke(bean, value);
72. } catch (Throwable ex) {
73. throw new RuntimeException("Could not set property '" + propertyName + "' to bean", ex);
74. }
75. }
76. }
77. }

转载于:https://www.cnblogs.com/LiuChunfu/p/6624732.html