1.通过Java反射创建运行时类的对象:
1 public static void test1() throws InstantiationException, IllegalAccessException {
2 Class<Person> clazz = Person.class;
3 //本质上内部仍是调用Person类的空参构造器
4 /*
5 要想使得该方法能够正常创建运行时类的对象,需满足以下几个条件:
6 1.运行时必须提供类的空参构造器
7 2.空参的构造器的范围权限得足够(通常设置为public)
8
9 在Javabean中要求提供一个public的空参构造器,原因:
10 1.便于通过类的反射,创建运行时类的对象
11 2.便于子类继承此类时,默认调用super()时,父类有该构造器
12 */
13 Person obj = clazz.newInstance();
14 System.out.println(obj);
15 }
2.Java反射动态性的体现:
1 public static void test2() {//反射的动态性
2 int num = new Random().nextInt(2);
3 String classPath = "";
4 System.out.println(num);
5 if (num == 0) {
6 classPath = "Person";
7 } else {
8 classPath = "Dog";
9 }
10 Object obj = null;
11 try {
12 obj = getInstance(classPath);
13 } catch (Exception e) {
14 throw new RuntimeException(e);
15 } finally {
16 System.out.println(obj);
17 }
18 }
19
20 public static Object getInstance(String classPath) throws Exception {
21 Class clazz = Class.forName(classPath);
22 return clazz.newInstance();
23 }