import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.text.MessageFormat;
class Person {
    /**
     * 18歲成年
     */
    private static final int ADULT_AGE = 18;
    /**
     * 年齡
     */
    private int     age;
    /**
     * 是否成年
     */
    private boolean adult;
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
        this.adult = age >= ADULT_AGE;
    }
    public boolean isAdult() {
        return adult;
    }
    public String toString() {
        return MessageFormat.format("age：{0}，adult：{1}", age, adult);
    }
}
/**
 * @author 二當(dāng)家的白帽子 https://le-yi.blog.csdn.net/
 */
public class Test {
    /**
     * 利用反射修改對象屬性
     * @param o
     * @param fieldName
     * @param value
     * @throws NoSuchFieldException
     * @throws IllegalAccessException
     */
    public static void changeObjectFieldByReflection(Object o, String fieldName, Object value) throws NoSuchFieldException, IllegalAccessException {
        Field field = o.getClass().getDeclaredField(fieldName);
        field.setAccessible(true);
        field.set(o, value);
    }
    /**
     * 利用內(nèi)省修改對象屬性
     * @param o
     * @param fieldName
     * @param value
     * @throws NoSuchFieldException
     * @throws IllegalAccessException
     */
    public static void changeObjectFieldByIntrospector(Object o, String fieldName, Object value) throws IntrospectionException, InvocationTargetException, IllegalAccessException {
        PropertyDescriptor pd = new PropertyDescriptor(fieldName, o.getClass());
        pd.getWriteMethod().invoke(o, value);
    }
    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IntrospectionException, InvocationTargetException {
        Person p = new Person();
        changeObjectFieldByReflection(p, "age", 20);
        System.out.println("反射修改屬性破壞類的封裝，使其內(nèi)部狀態(tài)錯(cuò)誤：");
        System.out.println(p);
        changeObjectFieldByIntrospector(p, "age", 18);
        System.out.println("內(nèi)省修改屬性未破壞類的封裝：");
        System.out.println(p);
    }
}

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.text.MessageFormat;
class Person {
    /**
     * 18歲成年
     */
    private static final int ADULT_AGE = 18;
    /**
     * 名字
     */
    private final String  name;
    /**
     * 身高
     */
    private       int     height;
    /**
     * 年齡
     */
    private       int     age;
    /**
     * 是否成年
     */
    private       boolean adult;
    public Person(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
    public int getHeight() {
        return height;
    }
    public void setHeight(int height) {
        this.height = height;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
        this.adult = age >= ADULT_AGE;
    }
    public boolean isAdult() {
        return adult;
    }
    public String toString() {
        return MessageFormat.format("name：{0}，height：{1}，age：{2}，adult：{3}", name, height, age, adult);
    }
}
/**
 * @author 二當(dāng)家的白帽子 https://le-yi.blog.csdn.net/
 */
public class Test {
    /**
     * 將orig的可讀屬性值拷貝到dest的可寫屬性中
     * @param dest
     * @param orig
     * @param <T>
     * @throws IntrospectionException
     * @throws InvocationTargetException
     * @throws IllegalAccessException
     */
    public static <T> void copyProperties(T dest, T orig) throws IntrospectionException, InvocationTargetException, IllegalAccessException {
        BeanInfo beanInfo = Introspector.getBeanInfo(orig.getClass());
        PropertyDescriptor[] pds = beanInfo.getPropertyDescriptors();
        for (PropertyDescriptor pd : pds) {
            Method rm = pd.getReadMethod();
            Method wm = pd.getWriteMethod();
            if (rm != null
                && wm != null) {
                Object value = rm.invoke(orig);
                wm.invoke(dest, value);
            }
        }
    }
    public static void main(String[] args) throws NoSuchFieldException, IllegalAccessException, IntrospectionException, InvocationTargetException {
        Person p2 = new Person("二當(dāng)家的");
        p2.setAge(18);
        p2.setHeight(180);
        System.out.println(p2);
        Person p1 = new Person("大當(dāng)家的");
        System.out.println(p1);
        System.out.println("將二當(dāng)家的可讀屬性值拷貝給大當(dāng)家的可寫屬性：");
        copyProperties(p1, p2);
        System.out.println(p1);
    }
}