我们新建一个类Person:

package person;

import sex.Sex;

public class Person{
	private String name = null;
	private int age = 0;
	private Sex sex = null;
	private String birthday = null;
	
	public Person(){};
	public Person(String name, int age, Sex sex, String birthday){
		String birMatch = "\\d{4}-\\d{2}-\\d{2}";
		this.name = name;
		this.age = age;
		this.sex = sex;
		if(birthday.matches(birMatch)){
			this.birthday = birthday;
		}
	}
	public void setInfo(String name, int age, Sex sex, String birthday){
		String birMatch = "\\d{4}-\\d{2}-\\d{2}";
		this.name = name;
		this.age = age;
		this.sex = sex;
		if(birthday.matches(birMatch)){
			this.birthday = birthday;
		}
	}
	public void setName(String name){
		this.name = name;
	}
	public void setAge(int age){
		this.age = age;
	}
	public void setSex(Sex sex){
		this.sex = sex;
	}
	public void setBirthday(String birthday){
		this.birthday = birthday;
	}
	public String getName(){
		return this.name;
	}
	public int getAge(){
		return this.age;
	}
	public Sex getSex(){
		return this.sex;
	}
	public String getBirthday(){
		return this.birthday;
	}
	public String toString(){
		return this.name + ", " + this.age + " years old, " + this.sex + ", " + this.birthday;
	}
}

　　新建一个枚举Sex：

package sex;

public enum Sex{
	MALE, FEMALE;
}

　　在Main.java主方法中获取Person类的属性：

package main;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import person.Person;
import sex.Sex;

public class Main {
	public static void main(String[] args){
		Class<?> cls = null;
		Object obj = null;
		try {
			cls = Class.forName("person.Person");
			obj = cls.newInstance();
			Field var1 = cls.getDeclaredField("name");
			var1.setAccessible(true);   //设置该属性能被外部访问
			var1.set(obj, "XiaoBiqiang");
			System.out.println(var1.get(obj));
			var1.setAccessible(false);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

　　运行结果：

XiaoBiqiang

　　注意：使用反射操作属性时最好通过setter和getter方法，因为扩大了属性的访问权限可能造成不安全