反射

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一切的操作都可以用Object完成
//通过Class类获得类名

Class c1 = null;

Class c2= null;

Class c3 = null;

c1 = Class.forName(“cn.test.Person”);//这种最常用

c2 = new Person().getClass();

c3 = Person.class;

System.out.println(c1.getName());

System.out.println(c2.getName());

System.out.println(c3.getName());

//通过Class类创建对象(这种创建对象的方式必须要无参构造方法)

/*String className= "cn.java.reflect.Person";Class ob = Class.forName(className);Person p = (Person)ob.newInstance();p.setName("haoren");p.setAge(20);System.out.println(p.getName());System.out.println(p.getAge());*/

//通过有参数的构造方法来创建对象

<span style="white-space:pre"></span>/*String className= "cn.java.reflect.Person";<span style="white-space:pre"></span>Class ob = Class.forName(className);<span style="white-space:pre"></span>Constructor[] cst = ob.getConstructors();<span style="white-space:pre"></span>//Person  p = (Person)cst[0].newInstance("huairen");//这里的构造函数的数组是有顺序的，按照参数的个数排序<span style="white-space:pre"></span>Person  p = (Person)cst[1].newInstance("huairen",20);<span style="white-space:pre"></span>System.out.println(p);*/

//取得类的结构

<span style="white-space:pre"></span>String className= "cn.java.reflect.Person";Class ob = Class.forName(className);//取得其全部实现的接口/*Class[] inter = ob.getInterfaces();for(int i=0;i<inter.length;i++){System.out.println(inter[i]);}*/

//取得其父类Class superClass = ob.getSuperclass();System.out.println(superClass);//取得全部的构造方法/*Constructor[] cs = ob.getConstructors();for(int i=0;i<cs.length;i++){System.out.println(cs[i]);}

//取出构造方法的形参for(int i=0;i<cs.length;i++){Class[] pr = cs[i].getParameterTypes();for(int j=0;j<pr.length;j++){System.out.println(pr[j]);}}//取出构造方法的权限for(int i=0;i<cs.length;i++){int md = cs[i].getModifiers();//System.out.println(md);System.out.println(Modifier.toString(md));//将数字1还原为public}//取得构造方法名System.out.println(cs[0].getName());*/

//取得全部方法Method[] mthd = ob.getMethods();/*for(int i=0;i<mthd.length;i++){System.out.println(mthd[i]);}*///获得方法的形参类型/*for(int i=0;i<mthd.length;i++){Class[] pa = mthd[i].getParameterTypes();for(int j=0;j<pa.length;j++){System.out.println(pa[j]);}}*/

//获得函数的名字/*for(int i=0;i<mthd.length;i++){String name = mthd[i].getName();System.out.println(name);}*///获得属性/*Field[] f = ob.getDeclaredFields();//filefor(int i=0;i<f.length;i++){System.out.println(f[i]);}*/

<span style="white-space:pre"></span>//通过反射调用类中的方法//没有参数的情况Method mth = ob.getDeclaredMethod("say");mth.invoke(ob.newInstance());<span style="white-space:pre"></span>//p.say();//有参数的情况/*Method mth = ob.getDeclaredMethod("say",String.class,int.class);mth.invoke(ob.newInstance(),"张三",80);*/

//修改属性Class<?> c = Class.forName("cn.java.reflect.Person");<span style="white-space:pre"></span>Constructor<?>[] cst = c.getConstructors();<span style="white-space:pre"></span>Person p = (Person) cst[1].newInstance("土豪",3);Field f = c.getDeclaredField("name");f.setAccessible(true);f.set(p, "wowo");System.out.print(f.get(p));

反射的应用

工厂设计模式

public class FactoryDemo1 {public static void main(String[] args) {// TODO Auto-generated method stub//System.out.println("吃苹果"+new Apple().eat());//new Apple().eat();//Factory.produce("苹果").eat();try {Factory.produce("cn.reflect.Apple").eat();Factory.produce("cn.reflect.Banana").eat();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();} }}class Factory{public static Fruit produce(String name) throws InstantiationException, IllegalAccessException, ClassNotFoundException{return (Fruit) Class.forName(name).newInstance();}}/*class Factory{public static Fruit produce(String name){if("吃苹果".equals(name)){return new Apple();}if("吃桔子".equals(name)){return new Orange();}if("吃香蕉".equals(name)){return new Banana();}return null;}}*/interface Fruit{void eat();}class Apple implements Fruit{@Overridepublic void eat() {System.out.println("吃苹果");}}class Orange implements Fruit{@Overridepublic void eat() {// TODO Auto-generated method stubSystem.out.println("吃桔子");}}class Banana implements Fruit{@Overridepublic void eat() {// TODO Auto-generated method stubSystem.out.println("吃香蕉");}}

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