Java核心---反射

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class ReflectDemo 
{
	public static void main(String[] args) throws Exception
	{
		String str = "abc";
		//三种不同的获取字节码的方法
		Class clazz1 = String.class;
		Class clazz2 = str.getClass();
		Class clazz3 = Class.forName("java.lang.String");
	}
}

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import java.lang.reflect.*;
class ReflectConsDemo 
{
	public static void main(String[] args)throws Exception 
	{
		Constructor[] cons = String.class.getConstructors();
        for(int i= 0;i<cons.length;i++)
		{
	    	System.out.println(cons[i]);
		}
	}
}

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import java.lang.reflect.*;
class ReflectConDemo 
{
	public static void main(String[] args)throws Exception 
	{
		Constructor con = String.class.getConstructor(StringBuffer.class);
		String str = (String)con.newInstance(new StringBuffer("java"));
		System.out.println(str);
	}
}

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import java.lang.reflect.*;
class Student  //被反射的类
{
	public String name;
	public int age = 12;
	public Student()
	{
		System.out.println("Student Student");
	}
	public Student(String name,int age) //构造方法重载
	{
		this.name = name;
		this.age = age;
	}	
}
class ReflectDemo
{
	public static void main(String[] ages)throws Exception
	{
		String studentName = Student.class.getField("name").getName();//获取反射类中成员变量的名称
		System.out.println(studentName);
	}
}

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import java.lang.reflect.*;
class Student  //被反射的类
{
	public String name;
	private int age;
	public Student()
	{
		System.out.println("Student Student");
	}
	public Student(String name,int age) //构造方法重载
	{
		this.name = name;
		this.age = age;
	}	
}
class ReflectDemo
{
	public static void main(String[] ages)throws Exception
	{
		String studentAge = Student.class.getField("age").getName();//获取反射类中成员变量的名称
		System.out.println(studentAge);
	}
}

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import java.lang.reflect.*;
class Student  //被反射的类
{
	public String name;
	private int age;
	public Student()
	{
		System.out.println("Student Student");
	}
	public Student(String name,int age) //构造方法重载
	{
		this.name = name;
		this.age = age;
	}	
}
class ReflectDemo
{
	public static void main(String[] ages)throws Exception
	{
		String studentAge = Student.class.getDeclaredField("age").getName();//获取反射类中成员变量的名称
		System.out.println(studentAge);
	}
}

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import java.io.*;
import java.util.*;
public class ReflectTest {
	public static void main(String[] args) throws Exception{	
		/*
		 *笔记本电脑使用usb设备 
		 */		 
		NoteBook computer=new NoteBook();
		computer.run();		
		//关联配置文件
		File file=new File("usb.properties");
		FileInputStream fis=new FileInputStream(file);
		//将配置文件信息缓存到集合中
		Properties ps=new Properties();
		ps.load(fis);
		//System.out.println(ps.size());
		for(int x=1;x<=ps.size();x++){
			String className=ps.getProperty("usb"+x);//获取配置文件中类名
			Class clazz=Class.forName(className);//获取类的Class对象
			USB usb=(USB)clazz.newInstance();//得到类实例
			computer.useUSB(usb);//开始使用			
		}
		fis.close();//关流
	}
}
//USB 接口
public interface USB {
	void open();
	void close();
}
//笔记本电脑
public class NoteBook {
	public void run(){
		System.out.println("NoteBook is run");
	}	
	public void useUSB(USB usb){
		if(usb!=null){
			usb.open();
			usb.close();
		}
	}
}
//鼠标
public class MouseUSB implements USB {
	public void open() {
		System.out.println("Mouse is use");
	}
	public void close() {
		System.out.println("Mouse is close");
	}
}
//键盘
public class KeyUSB implements USB {
	public void open() {
		System.out.println("Key is use");
	}
	public void close() {
		System.out.println("Key is close");
	}
}