JavaBean的两种内省操作

反射技术实际是已经能够完全满足我们对javaBean的各种操作了，但是为了方便JDK还是为我们提供了一套操纵JavaBean的API，，我们称这套API为内省操作(Introspector)

下面介绍两种JavaBean的内省操作

先定义个JavaBean类

public class userbean {private int age;private String name;public userbean() {super();}public userbean(int age, String name) {super();this.age = age;this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public String getName() {return name;}public void setName(String name) {this.name = name;}}

第一种简单内省

public class Introspector1 {/* * JavaBean的简单内省 */public static void main(String[] args) throws Exception {userbean bean = new userbean(20, "w");String propertyName = "name"; // 属性名// JavaBean的set方法String setValue = "wzl";setProperties(propertyName, bean, setValue);// JavaBean的get方法getProperties(propertyName, bean);}private static void getProperties(String propertyName, Object bean)throws Exception {PropertyDescriptor pd = new PropertyDescriptor(propertyName,bean.getClass());Method methodGet = pd.getReadMethod();Object retVal = methodGet.invoke(bean);System.out.println(retVal);}private static void setProperties(String propertyName, Object bean,Object setValue) throws Exception {PropertyDescriptor pd = new PropertyDescriptor(propertyName,bean.getClass());// 得到Javabean属性描述符Method methodSet = pd.getWriteMethod();methodSet.invoke(bean, setValue);}}

第二种复杂内省

public class Introspector2 {/* * JavaBean的复杂内省 */public static void main(String[] args) throws Exception {userbean bean = new userbean(20, "w");String propertyName = "name"; // 属性名// JavaBean的set方法String setValue = "wzl";setProperties(propertyName, bean, setValue);// JavaBean的get方法getProperties(propertyName, bean);}private static void getProperties(String propertyName, Object bean)throws Exception {// 把一个Java类当作JavaBean来看BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());// 得到所有的属性描述PropertyDescriptor[] pds = beanInfo.getPropertyDescriptors();Object retVal = new Object();for (PropertyDescriptor pd : pds) {if (pd.getName().equals(propertyName)) {Method methodGet = pd.getReadMethod();retVal = methodGet.invoke(bean);}}System.out.println(retVal);}private static void setProperties(String propertyName, Object bean,Object setValue) throws Exception {// 把一个Java类当作JavaBean来看BeanInfo beanInfo = Introspector.getBeanInfo(bean.getClass());// 得到所有属性描述PropertyDescriptor[] pds = beanInfo.getPropertyDescriptors();for (PropertyDescriptor pd : pds) {if (pd.getName().equals(propertyName)) {Method methodSet = pd.getWriteMethod();methodSet.invoke(bean, setValue);}}}}

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