java 反射机制

package com.cn.gaoyan;

class Person{
@Override
public String toString(){
return "Hello";
}
}

public class TestDemo {

public static void main(String args[]){

Class<?> demo1 = null;
Class<?> demo2 = null;
Class<?> demo3 = null;

//取得类的实例化对象，方法1
Person per = new Person();
demo1 = per.getClass();

//取得类的实例化对象，方法2
demo2 = Person.class;

//取得类的实例化对象，方法3
try {
demo3 = Class.forName("com.cn.gaoyan.Person");
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

System.out.println("demo1"+ demo1.getName());
System.out.println("demo2"+ demo2.getName());
System.out.println("demo3" + demo3.getName());

//通过反射实例化对象
Object obj = null;
try {
obj = demo1.newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

Person per1 = (Person)obj;
System.out.println(per1);
}

}

输出：

demo1com.cn.gaoyan.Persondemo2com.cn.gaoyan.Persondemo3com.cn.gaoyan.PersonHello

package com.cn.gao;import java.lang.reflect.Constructor;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;interface Fruit{public void eat();}class Apple implements Fruit{public Apple(){}@Overridepublic void eat() {// TODO Auto-generated method stubSystem.out.println("eat apple");}}class Orange implements Fruit{@Overridepublic void eat() {// TODO Auto-generated method stubSystem.out.println("eat orange");}}class Factory {public static Fruit getInstance(String className){Fruit f = null;try {f = (Fruit)Class.forName(className).newInstance();} catch (InstantiationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}return f;}}public class DemoFactory {public static void main(String args[]){Fruit f = (Fruit)Factory.getInstance("com.cn.gao.Apple");//取得该对象的构造函数System.out.println("**********取得该对象的构造函数");Constructor<?>[] cls = f.getClass().getConstructors();for(int i = 0; i < cls.length; i++){System.out.println(cls[i]);}//取得该对象所在类实现的接口System.out.println("**********取得该对象所在类实现的接口");Class<?> cls1[] = f.getClass().getInterfaces();for(int i = 0; i < cls1.length; i++){System.out.println(cls1[i]);}//取得该对象的普通方法System.out.println("**********取得该对象的普通方法");Method getMethod = null;try {getMethod = f.getClass().getMethod("eat");} catch (NoSuchMethodException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (SecurityException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println(getMethod);//通过反射机制调用该类的普通方法System.out.println("**********通过反射机制调用该类的普通方法");try {getMethod.invoke(f, null);} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (InvocationTargetException e) {// TODO Auto-generated catch blocke.printStackTrace();}System.out.println("**********调用该类的普通方法");f.eat();}}

输出：

**********取得该对象的构造函数public com.cn.gao.Apple()**********取得该对象所在类实现的接口interface com.cn.gao.Fruit**********取得该对象的普通方法public void com.cn.gao.Apple.eat()**********通过反射机制调用该类的普通方法eat apple**********调用该类的普通方法eat apple