第二十四部分_Java反射详解

package com.test.reflection;

import java.lang.reflect.Method;

public class DumpMethods
{
	public static void main(String[] args) throws Exception
	{
		// 加载并初始化命令行参数指定的类（运行期的行为）
		Class<?> classType = Class.forName(args[0]);
		
		// 获得类的所有方法
		Method[] methods = classType.getMethods();
		
		for(int i = 0; i < methods.length; i++)
		{
			System.out.println(methods[i]);
		}
	}
}

public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException
public final void java.lang.Object.wait() throws java.lang.InterruptedException
public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException
public boolean java.lang.Object.equals(java.lang.Object)
public java.lang.String java.lang.Object.toString()
public native int java.lang.Object.hashCode()
public final native java.lang.Class java.lang.Object.getClass()
public final native void java.lang.Object.notify()
public final native void java.lang.Object.notifyAll()

package com.test.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.Method;

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.getId() + " "
				+ 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;
	}
}

/*
 output:
	Class:com.test.reflection.Customer
	id:1
	name:Tom
	age:21
	Copy information:1 Tom 21
*/

public class PrivateClass
{
    private String sayHello(String name)
    {
        return "Hello: " + name;
    }

}

import java.lang.reflect.Method;

public class TestPrivate
{

    public static void main(String[] args) throws Exception
    {
        PrivateClass p = new PrivateClass();

        Class<?> classType = p.getClass();

        // 获取Method对象
        Method method = classType.getDeclaredMethod("sayHello",
                new Class[] { String.class });

        method.setAccessible(true); // 抑制Java的访问控制检查
        // 如果不加上上面这句，将会Error: TestPrivate can not access a member of class PrivateClass with modifiers "private"
        String str = (String) method.invoke(p, new Object[] { "zhangsan" });

        System.out.println(str);
    }
}

public class PrivateClass2
{
    private String name = "zhangsan";

    public String getName()
    {
        return name;
    }
}

import java.lang.reflect.Field;

public class TestPrivate2
{
    public static void main(String[] args) throws Exception
    {
        PrivateClass2 p = new PrivateClass2();
        Class<?> classType = p.getClass();

        Field field = classType.getDeclaredField("name");

        field.setAccessible(true); // 抑制Java对修饰符的检查
        field.set(p, "lisi");

        System.out.println(p.getName());
    }

}