1 package reflection;
2
3 import java.lang.reflect.Constructor;
4 import java.lang.reflect.Field;
5 import java.lang.reflect.InvocationTargetException;
6 import java.lang.reflect.Method;
7
8 public class Test09 {
9 public static void main(String[] args) throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException, NoSuchFieldException {
10 // 获得Class对象
11 Class c1 = Class.forName("reflection.User");
12
13 // 构造一个对象
14 /*User user = (User) c1.newInstance(); // 本质是调用类的无参构造器
15 System.out.println(user);*/
16
17 // 通过构造器创建对象
18 Constructor constructor = c1.getDeclaredConstructor(String.class, int.class, int.class);
19 User user2 = (User) constructor.newInstance("aa", 001, 001);
20 System.out.println(user2);
21
22 // 通过反射调用普通方法
23 User user3 = (User) constructor.newInstance();
24 // 通过反射获取一个方法
25 Method setName = c1.getMethod("setName", String.class);
26 setName.invoke(user3,"bb"); // invoke:激活(对象,"方法的值")
27 System.out.println(user3.getName());
28
29 // 通过反射操作属性
30 User user4 = (User) constructor.newInstance();
31 Field name = c1.getDeclaredField("name");
32
33
34 // 不能直接操作私有属性,需要关闭安全监测,属性或者方法的setAccessible(true)
35 name.setAccessible(true); //
36 name.set(user4,"ccc");
37 System.out.println(user4.getName());
38
39
40 }
41