java中反射操作构造方法

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java中反射操作构造方法

通过获取的构造创建对象

步骤:

1.获得Class对象

2获得构造

3.通过构造对象获得实例化对象

package com.itheima_01;import java.lang.reflect.Constructor;import java.lang.reflect.InvocationTargetException;/* *通过反射获取构造方法并使用 *Constructor<?>[] getConstructors()   *Constructor<T> getConstructor(Class<?>... parameterTypes)  * T newInstance()    * *Constructor： * T newInstance(Object... initargs)   */public class ReflectDemo2 {public static void main(String[] args) throws ReflectiveOperationException {Class clazz = Class.forName("com.itheima_01.Student");//method(clazz);//Constructor<T> getConstructor(Class<?>... parameterTypes) //method2(clazz);//method3(clazz);Object obj = clazz.newInstance();System.out.println(obj); }private static void method3(Class clazz)throws NoSuchMethodException, InstantiationException, IllegalAccessException, InvocationTargetException {Constructor c = clazz.getConstructor(String.class,int.class);//获取有参构造，参数1类型为String，参数2类型为intSystem.out.println(c);Object obj = c.newInstance("lisi",30);System.out.println(obj);}private static void method2(Class clazz)throws NoSuchMethodException, InstantiationException, IllegalAccessException, InvocationTargetException {Constructor c = clazz.getConstructor();//获取无参构造System.out.println(c);Object obj = c.newInstance();System.out.println(obj);}private static void method(Class clazz) {//Constructor<?>[] getConstructors() :获取所有public修饰的构造方法 Constructor[] cs = clazz.getConstructors();for (int i = 0; i < cs.length; i++) {System.out.println(cs[i]);}}}

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