Java中的反射

import java.lang.reflect.Method;

public class DumpMethods {
	
	public static void main(String[] args) throws Exception{
		
		//Class对象描述了某个特定的类对象
		Class<?> classType = Class.forName("java.lang.String");
		
		//通过反射获取到所有的方法
		Method[] methods = classType.getDeclaredMethods();
		
		//打印所有的方法
		for(Method m : methods){
			System.out.println(m);
		}
	}

}

import java.lang.reflect.Method;

public class InvokeTester {

	public int add(int parm1, int parm2) {
		return parm1 + parm2;
	}

	public String echo(String message) {
		return "hello:" + message;
	}

	public static void main(String[] args) throws Exception {
		// InvokeTester test = new InvokeTester();
		// System.out.println(test.add(1, 2));
		// System.out.println(test.echo("Java"));
		
		Class<?> classType = InvokeTester.class;
		
		//通过反射生成一个InvokeTester类型的对象
		Object o = classType.newInstance();
		
		//通过反射获取到add方法
		Method addMethod = classType.getMethod("add", new Class[] { int.class,
				int.class });
		
		//调用对象的add方法并把参数传进去
		System.out.println(addMethod.invoke(o,new Object[]{1,2}));
		
		//通过反射获取到echo方法
		Method echoMethod = classType.getMethod("echo", new Class[]{String.class});
		
		//调用对象的echo方法并把参数传进去
		System.out.println(echoMethod.invoke(o, new Object[]{"Java"}));
	}
}

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

public class ReflectTest {

	// 该方法实现对Customer的拷贝
	public static Object copy(Object object) throws Exception {
		Class<?> classType = object.getClass();

		Object objectCopy = classType.getConstructor(new Class[] {})
				.newInstance(new Object[] {});

		Field[] fields = classType.getDeclaredFields();

		for (Field field : fields) {
			String name = field.getName();
			String firstLetter = name.substring(0, 1).toUpperCase();// 将属性的首字母转换为大写

			String getMethodName = "get" + firstLetter + name.substring(1);
			String setMethodName = "set" + firstLetter + name.substring(1);

			Method getMethod = classType.getMethod(getMethodName,
					new Class[] {});
			Method setMethod = classType.getMethod(setMethodName,
					new Class[] { field.getType() });

			Object value = getMethod.invoke(object, new Object[] {});

			setMethod.invoke(objectCopy, new Object[] { value });
		}

		return objectCopy;
	}

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

		Customer c = new Customer("Tom", 20);
		c.setId(1L);
		Object o = copy(c);
		Customer customerCopy = (Customer) o;

		System.out.println(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;
	}

}

import java.lang.reflect.Array;

public class ArrayTester {
	
	public static void main(String[] args) {
		
		Class<?> classType = String.class;
		
		Object array = Array.newInstance(classType, 10);
		
		Array.set(array, 5, "hello");
		
		String s = (String) Array.get(array, 5);
		
		System.out.println(s);
	}
}

import java.lang.reflect.Array;

public class ArrayTester2 {
	
	public static void main(String[] args) {
		
		int[] dims = new int[]{5,10,15};
		
		Object array = Array.newInstance(Integer.TYPE, dims);
		
		Object arrayObj = Array.get(array, 3);
		
//		Class<?> classType = arrayObj.getClass().getComponentType();
//		
//		System.out.println(classType);
		
		arrayObj = Array.get(arrayObj, 5);
		
		Array.set(arrayObj, 10, 37);
		
		int[][][] arrayCast = (int[][][]) array;
		
		System.out.println(arrayCast[3][5][10]);
		
	}
	
}