Java反射

public class ReflectionTest {
    public static void main(String[] args) throws Exception {
        test001();
    }

    public static void test001() throws Exception {
        Class<Person> clazz = Person.class;
        Person p = clazz.newInstance();
        //1、调用属性
        Field clazzField = clazz.getField("name");
        clazzField.set(p, "李四");
        System.out.println(clazzField.get(p));
        //2、调用方法
        Method clazzMethod = clazz.getMethod("showInfo");
        clazzMethod.invoke(p);
        /*---------------------------------------------------------*/
        System.out.println("---------------------------------------------------------");
        Class personClass = Class.forName("com.bilibili.cloud.test.Person");
        //3、调用私有构造器
        Constructor<Person> constructor = personClass.getDeclaredConstructor(String.class, int.class);
        //设置构造器访问权限
        constructor.setAccessible(true);
        Person person = constructor.newInstance("张三", 20);
        System.out.println(person.getName());
        System.out.println(person.getAge());
        //4、调用私有属性
        Field ageField = personClass.getDeclaredField("age");
        // 设置属性可访问
        ageField.setAccessible(true);
        ageField.set(person, 21);
        System.out.println(ageField.get(person));
        //5、调用私有方法
        Method showNation = personClass.getDeclaredMethod("showNation", String.class);
        //设置方法可访问
        showNation.setAccessible(true);
        System.out.println(showNation.invoke(person, "北京"));
    }

    /**
     * 反射动态性 1
     * @param className
     * @return
     * @param <T>
     * @throws Exception
     */
    public <T> T getInstance(String className) throws Exception {
        Class<?> clazz = Class.forName(className);
        Constructor<?> declaredConstructor = clazz.getDeclaredConstructor();
        declaredConstructor.setAccessible(true);
        return (T) declaredConstructor.newInstance();
    }

    /**
     *  反射动态性 2
     * @param className
     * @param methodName
     * @return
     * @throws Exception
     */
    public Object invoke(String className,String methodName ) throws Exception {
        Object instance = getInstance(className);
        Class<?> clazz = instance.getClass();
        //调用私有方法
        Method declaredMethod = clazz.getDeclaredMethod(methodName);
        declaredMethod.setAccessible(true);
        return declaredMethod.invoke(instance);
    }
}