新建Person類：

package test.reflection.cal;

import test.reflection.annotation.AnnoTest;

/**
 * 用於測試反射的類
 * @author Administrator
 *
 */
public class Person {
	
	private int id;
	private String name;
	
//	public Person(){}

	public int getId() {
		return id;
	}

	public void setId(int id) {
		this.id = id;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}
	
	/**
	 * 待測試的方法  
	 * private 修飾 
	 *  帶註解
	 * @param i
	 * @return
	 */
	@AnnoTest(value = "what",name = "are you doing")
	private String changeInfo(String i){
		return i+"  "+name;
	}

	@Override
	public String toString() {
		return "Person [id=" + id + ", name=" + name + "]";
	}
	
	

}
 

新建註解：

package test.reflection.annotation;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
 * 自定義註解
 * @author Administrator
 *
 */
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface AnnoTest {
	
	String name() default "this is an annotation";

	String value() default "";

}
 

測試類：

package test.reflection.test;

import java.lang.reflect.Method;

import test.reflection.annotation.AnnoTest;
import test.reflection.cal.Person;

/**
 * 反射測試
 * 
 * @author Administrator
 *
 */
public class ReflectionTest {

	@SuppressWarnings("unchecked")
	public static void main(String[] args) throws Throwable, SecurityException {

		Person p = new Person();
		Class<Person> clazz = (Class<Person>) p.getClass();
		// 獲取所有的方法
		Method[] methods = clazz.getDeclaredMethods();
		System.out.println("Person 的所有方法：");
		for (Method method : methods) {
			System.out.println("" + method.getName());
		}
		System.out.println();
		// 獲取getName方法，沒有賦初值，結果為null 
		Method m0 = clazz.getDeclaredMethod("getName");
		System.out.println("getName:  " + m0.invoke(p));
		// 獲取setName方法
		Method mset = clazz.getDeclaredMethod("setName", String.class);
		mset.invoke(p, "dam");

		System.out.println("setName之後  " + p.toString());
		// 獲取changeInfo 方法
		Method m1 = clazz.getDeclaredMethod("changeInfo", String.class);
		m1.setAccessible(true);// changeInfo方法用private修飾 ，這裡需要設定為true才能獲取
		String res = (String) m1.invoke(p, " haha");
		System.out.println("changeInfo:" + res);

		// 獲取changeInfo 方法上的註解
		AnnoTest annoTest = (AnnoTest) m1.getAnnotation(AnnoTest.class);
		System.out.println(annoTest.name());// 獲取註解中的值
		System.out.println(annoTest.value());// 獲取註解中的值

	}
}