1 package com.corn;  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 TestReflect {  9  10     public static void main(String[] args) { 11  12         // 获取“类类型对象”  方法1 13         Class<?> c0 = User.class; 14  15         // 获取“类类型对象”  方法2 16         User user1 = new User(); 17         Class<?> c1 = user1.getClass(); 18  19         User user2 = new User(); 20         Class<?> c2 = user2.getClass(); 21  22         System.out.println("user class instance 0:" + c0); //user class instance 0:class com.corn.User 23         System.out.println("user class instance 1:" + c1); //user class instance 1:class com.corn.User 24         System.out.println("user class instance 2:" + c2); //user class instance 2:class com.corn.User 25  26         //c0 == c1 :true, c1 == c2 :true 27         System.out.println("c0 == c1 :" + (c0 == c1) + ", c1 == c2 :" + (c1 == c2)); 28  29         try { 30             // 获取“类类型对象”  方法3 31             Class<?> c3 = Class.forName("com.corn.User"); 32             System.out.println("user class c3:" + c3); //user class c3:class com.corn.User 33  34             try { 35                 User user3 = (User) c3.newInstance(); 36  37                 //Constructor public com.corn.User(int,java.lang.String,int) 38                 //Constructor public com.corn.User(int,java.lang.String) 39                 //Constructor public com.corn.User() 40                 Constructor<?>[] cons = c3.getConstructors(); 41                 for (int i = 0; i < cons.length; i++) { 42                     // 一次返回类定义中所有public修饰符修饰的“构造器对象”,其与类定义中的构造器顺序不一定相同 43                     System.out.println("Constructor " + cons[i]); 44                 } 45  46                 try { 47                     User user4 = (User) cons[1].newInstance(51, "corn"); 48                     //user instance 4:user instance uid:51 name:corn 49                     System.out.println("user instance 4:" + user4); 50  51                     // 返回特定参数类型的“构造器对象”所新建的实例 52                     User user40; 53                     user40 = (User) c3.getConstructor(int.class, String.class).newInstance(520, "corn0"); 54                     //user instance 40:user instance uid:520 name:corn0 55                     System.out.println("user instance 40:" + user40); 56  57                     // 返回该类“类类型对象”的所有的父类“类类型对象” 58                     Class<?> father = c3.getSuperclass(); 59                     //father class instance class com.corn.Person 60                     System.out.println("father class instance " + father); 61  62                     //返回类对象所有的接口对象（其实也是类类型对象）数组 63                     Class<?>[] interfaceArray = c3.getInterfaces(); 64                     //interface class instance 0 interface com.corn.Workable 65                     //interface class instance 1 interface com.corn.Thinkable 66                     for (int i = 0; i < interfaceArray.length; i++) { 67                         // 与implements中接口顺序相同 68                         System.out.println("interface class instance " + i + " " + interfaceArray[i]); 69                     } 70  71                 } catch (IllegalArgumentException e) { 72                     e.printStackTrace(); 73                 } catch (InvocationTargetException e) { 74                     e.printStackTrace(); 75                 } 76  77             } catch (InstantiationException e) { 78                 e.printStackTrace(); 79             } catch (IllegalAccessException e) { 80                 e.printStackTrace(); 81             } 82         } catch (ClassNotFoundException e) { 83             e.printStackTrace(); 84         } catch (Exception e) { 85             e.printStackTrace(); 86         } 87  88         // 返回“类类型对象”所具有的全部属性实例/对象 89         Field[] fieldArray = c0.getDeclaredFields(); 90         //filed 0 private int com.corn.User.uid 91         //filed 1 private java.lang.String com.corn.User.name 92         //filed 2 private int com.corn.User.age 93         for (int i = 0; i < fieldArray.length; i++) { 94             System.out.println("filed " + i + " " + fieldArray[i]); 95         } 96  97         User u = new User(12, "yumidi", 99); 98  99         try {100             // 直接获取private/私有属性的值101             Field nameField = c0.getDeclaredField("name");102             //取消Java对访问修饰符的检查   103             nameField.setAccessible(true);104             String nameValue =http://www.mamicode.com/ (String) nameField.get(u);105             //name:yumidi106             System.out.println("name:" + nameValue);107 108             // 直接改变private/私有属性的值109             nameField.set(u, "corn");110             //new name:corn111             System.out.println("new name:" + u.getName());112 113         } catch (NoSuchFieldException e) {114             e.printStackTrace();115         } catch (SecurityException e) {116             e.printStackTrace();117         } catch (Exception e) {118             e.printStackTrace();119         }120 121         //访问私有方法122         try {123             Method method = c0.getDeclaredMethod("getResult");124             //取消Java对访问修饰符的检查125             method.setAccessible(true);126             int result = (int) method.invoke(u);127             //result:1000128             System.out.println("result:" + result);129 130         } catch (NoSuchMethodException e) {131             e.printStackTrace();132         } catch (SecurityException e) {133             e.printStackTrace();134         } catch (Exception e) {135             e.printStackTrace();136         }137 138     }139 }140 141 class User extends Person implements Workable, Thinkable {142 143     private int uid;144     private String name;145     private int age;146 147     public User() {148 149     }150 151     private User(int uid) {152         this.uid = uid;153     }154 155     protected User(String name) {156         this.name = name;157     }158 159     public User(int uid, String name) {160         this.uid = uid;161         this.name = name;162     }163 164     public User(int uid, String name, int age) {165         this.uid = uid;166         this.name = name;167         this.age = age;168     }169 170     public int getUid() {171         return uid;172     }173 174     public void setUid(int uid) {175         this.uid = uid;176     }177 178     public String getName() {179         return name;180     }181 182     public void setName(String name) {183         this.name = name;184     }185 186     public int getAge() {187         return age;188     }189 190     public void setAge(int age) {191         this.age = age;192     }193 194     private int getResult() {195         return 1000;196     }197 198     @Override199     public String toString() {200         return "user instance uid:" + this.uid + " name:" + this.name;201     }202 203 }204 205 class Person {206 207 }208 209 interface Workable {210 211 }212 213 interface Thinkable {214 215 }