反射的应用

反射应用:

public static void main(String[] args) throws Exception {
        Class clazz = Person.class;

        //对Person公有的构造器访问
        Constructor constructor = clazz.getConstructor(String.class, Integer.class);
        Person person = (Person) constructor.newInstance("刘富贵aa", 66);
        System.out.println(person.toString());

        //对Person对象私有的属性访问
        Field age = clazz.getDeclaredField("age");
        age.setAccessible(true);//设置无障碍模式，也就是可以访问私有的对象
        age.set(person, 16);
        System.out.println(person.toString());

        //对Person对象私有的构造器的调用
        Constructor constructor2 = clazz.getDeclaredConstructor(String.class);//调用构建名称的构造器
        constructor2.setAccessible(true);//设置无障碍模式，也就是可以访问私有的对象
        person = (Person) constructor2.newInstance("sky");
        System.out.println(person.toString());

        //对Person对象公有的方法的调用
        Method method = clazz.getDeclaredMethod("sayHello", String.class);
        method.invoke(person, "张大炮");

        //对Person对象的私有方法的调用
        Method method2 = clazz.getDeclaredMethod("makeFriend", String.class);
        method2.setAccessible(true);//设置无障碍模式，也就是可以访问私有的对象
        method2.invoke(person, "李二牛");

        Method friendName = clazz.getDeclaredMethod("friendName");
        friendName.setAccessible(true);
        System.out.println(friendName.invoke(person));
    }

文件的读取

@Test
public static void main(String[] args) {
Properties properties = new Properties();
try {
// ClassLoader classLoader = LoaderTest.class.getClassLoader();
// InputStream resourceAsStream = classLoader.getResourceAsStream("jdbc1.properties");
FileInputStream resourceAsStream = new FileInputStream("src\\jdbc1.properties");
properties.load(resourceAsStream);       
 System.out.println(properties.getProperty("user") + "\\t" + properties.getProperty("password"));
    } catch (Exception e) {
        e.printStackTrace();
    }

}