JAVA反射机制事例一

import java.lang.reflect.*;
public class ReflectTester {
  public Object copy(Object object) throws Exception{
    //获得对象的类型
    Class classType=object.getClass();
    System.out.println("Class:"+classType.getName());
    //通过默认构造方法创建一个新的对象
    Object objectCopy=classType.getConstructor(new Class[]{}).newInstance(new Object[]{});
    //获得对象的所有属性
    Field fields[]=classType.getDeclaredFields();
    for(int i=0; i<fields.length;i++){
          Field field=fields[i];
          String fieldName=field.getName();
          String firstLetter=fieldName.substring(0,1).toUpperCase();
          //获得和属性对应的getXXX()方法的名字
          String getMethodName="get"+firstLetter+fieldName.substring(1);
          //获得和属性对应的setXXX()方法的名字
          String setMethodName="set"+firstLetter+fieldName.substring(1);
          //获得和属性对应的getXXX()方法
          Method getMethod=classType.getMethod(getMethodName,new Class[]{});
//获得和属性对应的setXXX()方法
          Method setMethod=classType.getMethod(setMethodName,new Class[]{field.getType()});
          //调用原对象的getXXX()方法
          Object value=getMethod.invoke(object,new Object[]{});
          System.out.println(fieldName+":"+value);
          //调用拷贝对象的setXXX()方法
         setMethod.invoke(objectCopy,new Object[]{value});
    }
    return objectCopy;
  }
  public static void main(String[] args) throws Exception{
    Customer customer=new Customer("Tom",21);
    customer.setId(new Long(1));
    Customer customerCopy=(Customer)new ReflectTester().copy(customer);
    System.out.println("Copy information:"+customerCopy.getName()+" "+customerCopy.getAge());
  }
}
class Customer{
  private Long id;
  private String name;
  private int age;
  
  public Customer(){}
  public Customer(String name,int age){
    this.name=name;
    this.age=age;
  }
  
  public Long getId(){return id;}
  public void setId(Long id){this.id=id;}
  
  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;}
}

 

 输出结果

Class:com.lwf.exception.Customer
id:1
name:Tom
age:21
Copy information:Tom 21

 

下面讲一下Class的getFields与getDeclaredFields的区别：

/**
 * 
 */
package com.lwf.exception;

import java.lang.reflect.Field;
import java.util.Date;


public class TestClassField {

	/** 
	 * @Title: main 
	 * @Description: TODO
	 * @param @param args   
	 * @return void  
	 * @throws 
	 */
	public static void main(String[] args) {
		Pig p = new Pig();
		
		Field [] fields = p.getClass().getDeclaredFields();
		for (int i = 0; i < fields.length; i++) {
			Field f = fields[i];
			System.out.println(f.getName() + "," + f.getType().toString());
		}
		//fields = null;
		System.out.println("----------------------------");
		fields = p.getClass().getFields();
		for (int i = 0; i < fields.length; i++) {
			Field f = fields[i];
			System.out.println(f.getName() + "," + f.getType().toString());
		}
		
	}

}


class Animal{
	private String name;
	protected String color;
	public String sex;
	/**
	 * @return the name
	 */
	public String getName() {
		return name;
	}
	/**
	 * @param name the name to set
	 */
	public void setName(String name) {
		this.name = name;
	}
	/**
	 * @return the color
	 */
	public String getColor() {
		return color;
	}
	/**
	 * @param color the color to set
	 */
	public void setColor(String color) {
		this.color = color;
	}
	/**
	 * @return the sex
	 */
	public String getSex() {
		return sex;
	}
	/**
	 * @param sex the sex to set
	 */
	public void setSex(String sex) {
		this.sex = sex;
	}
}

class Pig extends Animal{
	public int age;
	Date birthDay;
	/**
	 * @return the age
	 */
	public int getAge() {
		return age;
	}
	/**
	 * @param age the age to set
	 */
	public void setAge(int age) {
		this.age = age;
	}
	/**
	 * @return the birthDay
	 */
	public Date getBirthDay() {
		return birthDay;
	}
	/**
	 * @param birthDay the birthDay to set
	 */
	public void setBirthDay(Date birthDay) {
		this.birthDay = birthDay;
	}
}

 输出结果：

age,int
birthDay,class java.util.Date
----------------------------
age,int
sex,class java.lang.String

 

getFields与getDeclaredFields的区别如下

getFields返回类及所有父类的公有属性；getDeclaredFields只返回类自身的所有属性。