JAVA中的反射机制

原文链接

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;

public class ReflectTest {

	public static void main(String[] args) throws Exception {
		String str = "sun.mgp.Customer";

		Class<?> c = Class.forName(str);

		// 获取构造函数及其中参数
		Constructor<?>[] con = c.getConstructors();
		System.out.println("构造函数名为：" + con[0].getName());
		for (int i = 0; i < con.length; i++) {
			System.out.println("构造函数为：" + con);
			Class<?>[] cl = con[i].getParameterTypes();
			for (int j = 0; j < cl.length; j++) {
				System.out.println("参数为：" + cl[j].getName());
			}
		}
		System.out.println("--------------------------");
		// 获取方法及参数
		Method[] met = c.getMethods();
		for (int i = 0; i < met.length; i++) {
			System.out.println(met[i].getName());
			Class<?>[] cm = met[i].getParameterTypes();
			for (int j = 0; j < cm.length; j++)
				System.out.println("参数为：" + cm[j].getName());
		}

	}
}

class NewInstn {

	public static void main(String[] args) {
		String str = "sun.mgp.Customer";
		try {
			Class<?> c = Class.forName(str);

			c.newInstance();// 获得无参构造函数的实例

			Constructor<?> con = c.getConstructor(new Class[] {});// 得到不带参数的构造函数
			con.newInstance(new Object[] {});

			// 带参构造函数
			Constructor<?> conr = c.getConstructor(new Class[] { Class.forName("java.lang.String"), Class.forName("java.lang.String") });
			Object objr = conr.newInstance(new Object[] { "hello", "world" });

			// 调用类中的test方法
			Method met = c.getMethod("test", new Class[] {});
			met.invoke(objr);

		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}
}

class Customer {

	public Customer() {
		System.out.println("无参构造函数被调用");
	}

	public Customer(String a, String p) {
		System.out.println("带参构造函数被调用");
	}

	public void printInfo() {
		System.out.println("hello,world!");
	}

	public void test() {
		System.out.println("this is test");
	}
}