1 package com.reflex;
2
3 import java.lang.reflect.Constructor;
4
5 import java.lang.reflect.Field;
6
7 import java.lang.reflect.InvocationTargetException;
8
9 import java.lang.reflect.Method;
10
11 import java.util.ArrayList; import java.util.List;
12
13 import org.junit.Test;
14
15 //反射定义：反射就是加载类，并解刨类的各个组成部分 public class Demo1 {
16
17 public static void main(String[] args) throws ClassNotFoundException {
18 // TODO Auto-generated method stub
19 //使用反射，首先要知道有一个Class类代表某一类的字节码
20 //获取某一类字节码的三种办法
21 //1
22 Class clazz = Class.forName("/Test/src/daythree/reflex/Person.java");
23 //2
24 Class clazz1 = new Person().getClass();
25 //3
26 Class clazz2 = Person.class;
27 }
28 @Test //非私有构造函数
29 public void reFlex() throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
30 Class clazz = Class.forName("daythree.reflex.Person");
31 Constructor cs = clazz.getConstructor(String.class); //没有参数填写null
32 Person person = (Person) cs.newInstance("12233"); // 实例化
33 }
34
35 @Test
36 public void reFlexS() throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
37 Class clazz = Class.forName("daythree.reflex.Person");
38 Constructor cs = clazz.getDeclaredConstructor(List.class);
39 cs.setAccessible(true);//暴力反射
40 Person person = (Person) cs.newInstance(new ArrayList<>());========
41
42 }
43 @Test //方法反射 getMethod 第一个参数方法名 第二个参数方法参数 invoke第一个是方法所在类第二个参数
44 public void FangfaFlex() throws Exception{
45 Person person = new Person();
46 Class clazz = Class.forName("daythree.reflex.Person");
47 Method method = clazz.getMethod("Demo2",null);
48 method.invoke(person, null);
49 }
50
51 @Test //字段发射 从类中赋值 或者取值
52 public void ZiduanFlex() throws Exception{
53 Person person = new Person();
54 Class clazz = Class.forName("daythree.reflex.Person");
55 Field field = clazz.getField("name");
56 //String name = (String)field.get(person); 取值
57 field.set(person, "dashage"); //赋值
58 System.out.println(field.getType()); //取类别
59 System.out.println(person.name);
60 }
61 }
62
63 class Person {
64
65 public String name = "shadage";
66
67 public Person() {
68
69 }
70
71 public Person(String a) {
72 System.out.println(a);
73 }
74
75 private Person(List ls) {
76 System.out.println("true");
77 }
78
79 public int[] Demo1(int[] a){
80 int b[] = new int[]{1,2,3};
81 return b;
82 }
83 public Class[] Demo1(int a){
84 Class b[] = new Class[]{String.class,int.class};
85 return b;
86 }
87 public void Demo2(){
88 System.out.println("方法输出");
89 }
90 }
