反射机制

package org.dcl.demo;

interface Fruit {
	public void eat();
}

class Apple implements Fruit {

	@Override
	public void eat() {
		// TODO Auto-generated method stub
		System.out.println("*** 吃苹果.");
	}
	
}

class Orange implements Fruit {

	@Override
	public void eat() {
		// TODO Auto-generated method stub
		System.out.println("*** 吃橘子.");
	}
	
}

class Factory {
	public static Fruit getFruit(String className) {
		Fruit instance = null;
		try {
			Class<?> cls = Class.forName(className);
			instance = (Fruit)cls.newInstance();
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return instance;
	}
}

public class APIDemo {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Fruit f1 = Factory.getFruit("org.dcl.demo.Apple");
		f1.eat();
		Fruit f2 = Factory.getFruit("org.dcl.demo.Orange");
		f2.eat();
	}

}

package org.dcl.demo;

interface Fruit {	
}

class Apple implements Fruit,Cloneable {	
}

public class APIDemo {

	/**
	 * @param args
	 * @throws ClassNotFoundException 
	 */
	public static void main(String[] args) throws ClassNotFoundException {
		// TODO Auto-generated method stub
		Class<?> cls = Class.forName("org.dcl.demo.Apple");
		System.out.println(cls.getSuperclass().getName());
		Class<?> it[] = cls.getInterfaces();
		for(int i = 0; i < it.length; i++) {
			System.out.println(it[i].getName());
		}
	}

}

package org.dcl.demo;

import java.lang.reflect.Constructor;

class Person {
	private String name;
	private int age;
	public Person(){}
	public Person(String name){
		this.name = name;
	}
	public Person(String name, int age){
		this.name = name;
		this.age = age;
	}
	
	@Override
	public String toString() {
		return "姓名: " + this.name + ",年龄: " + this.age;
	}
}

public class APIDemo {

	/**
	 * @param args
	 * @throws ClassNotFoundException 
	 */
	public static void main(String[] args) throws ClassNotFoundException {

		Class<?> cls = Class.forName("org.dcl.demo.Person");
		Constructor<?> cons[] = cls.getConstructors();
		for(int i = 0; i < cons.length; i++) {
			System.out.println(cons[i]);
		}
		
	}

}

package org.dcl.demo;

import java.lang.reflect.Constructor;

class Person {
	private String name;
	private int age;

	public Person(String name, int age){
		this.name = name;
		this.age = age;
	}
	
	@Override
	public String toString() {
		return "姓名: " + this.name + ",年龄: " + this.age;
	}
}

public class APIDemo {

	/**
	 * @param args
	 * @throws ClassNotFoundException 
	 * @throws NoSuchMethodException 
	 * @throws SecurityException 
	 */
	public static void main(String[] args) {
	
		try {
			Class<?> cls = Class.forName("org.dcl.demo.Person");
			Constructor<?> constructor =  cls.getConstructor(String.class, int.class);
			Person person = (Person)constructor.newInstance("diao", 26);
			System.out.println(person);
		} catch (Exception e) {
			e.printStackTrace();
		} 
	}

}
如果没有无参的构造方法的话,就要获得Constructor对象,然后Constructor对象中有newInstance方法,把值设置进去就可以了!