java的反射实现_hawkol_新浪博客

package com.hawkol.reflex_class;

import java.io.BufferedReader;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Modifier;

public class Test {

//1.java的反射

//2.Class 自描述类（描述当前对象自己的一个类，通过该类可以获得类的属性和方法，（包括私有属性和构造方法）

public static void main(String[] args) throws Exception {

getClass1();

getClass2();

getClass3();

System.out.println("---------------------------------");

Person person=new Person();

//设置基于配置的松耦合的程序

BufferedReader br=new BufferedReader(new FileReader("e:\\discount.txt"));

String string=br.readLine();

Class  cls=Class.forName(string);

person.buy((Discount)cls.newInstance());

printConstructor(Person.class);

getField(Person.class);

setField(Person.class);

}

private static void setField(Class cls) {

try {

//private 字段的赋值和获取

//Field f1=cls.getField("pid");

Field f1=cls.getDeclaredField("pid");//获得私有字段

f1.setAccessible(true);//如果没有这一句会抛出异常

Object object=cls.newInstance();

f1.set(object, 1);

System.out.println(f1.get(object));

//public 字段的赋值和获取

Field f2=cls.getField("name");

f2.set(object,"hawkol");

System.out.println(f2.get(object));

} catch (Exception e) {

e.printStackTrace();

}

}

//字段的反射

static  void getField(Class cls){

Field [] fields=cls.getDeclaredFields();

for(Field f:fields){

System.out.println(f);

System.out.println("修饰符："+Modifier.toString(f.getModifiers()));

System.out.println("类型："+f.getType());

System.out.println("名称："+f.getName());

}

}

//构造方法反射

static void printConstructor(Class cls){

//3.得到所有构造函数

Constructor []cs =cls.getDeclaredConstructors();

for(Constructor c:cs){

System.out.println(c);

System.out.println("修饰符："+Modifier.toString(c.getModifiers()));

System.out.print("参数：");

Class []pt=c.getParameterTypes();

for(Class p:pt){

System.out.print(p.getName()+" ");

}

System.out.println();

}

//2.得到有参构造函数

//1.得到无参构造函数

}

//3.Class里面有一个静态方法Class.forName("") 类全名（包名+类名）

static void getClass3(){

try {

Class class1=Class.forName("com.hawkol.reflex_class.Person");

System.out.println("Run getClass3:"+class1.getName());

} catch (ClassNotFoundException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

//2.通过.class属性

static void getClass2(){

Class class1=Person.class;

System.out.println("Run getClass2:"+class1.getName());

}

//1.获得Class对象的方法 Object有一个方法，getClass;

static void getClass1() throws Exception{

Person person=new Person();

Class class1=person.getClass();

System.out.println("Run getClass1:"+class1.getName());

}

}

class Person{

private int pid;

public String name;

protected int age;

private double price=200;

public Person(int pid, String name, int age) {

super();

this.pid = pid;

this.name = name;

this.age = age;

System.out.println("Person2()");

}

public Person() {

super();

System.out.println("Person1()");

}

public void buy(Discount d){

System.out.println("原价："+price);

System.out.println("折扣："+d.discount());

System.out.println("卖价："+price*d.discount()/100);

}

public int getPid() {

return pid;

}

public void setPid(int pid) {

this.pid = pid;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getAge() {

return age;

}

public void setAge(int age) {

this.age = age;

}

}