Java中Reflect的基本使用

Posted 2021-01-15 Mr. Tan

首先在package reflect下定义了一个类Book

 1 package reflect;
 2 
 3 class Book{
 4     private String title;
 5     private double price;
 6     public Book() {
 7         this("Java开发", 20.00);
 8     }
 9     public Book(String title, double price) {
10         this.title = title;
11         this.price = price;
12     }
13     public String getTitle() {
14         return title;
15     }
16     public void setTitle(String title) {
17         this.title = title;
18     }
19     public double getPrice() {
20         return price;
21     }
22     public void setPrice(double price) {
23         this.price = price;
24     }
25     @Override
26     public String toString() {
27         return "标题: " + this.title + ", 价格：" + this.price;
28     }
29 }

View Code

 1 package reflect;
 2 
 3 import java.lang.reflect.Constructor;
 4 import java.lang.reflect.Method;
 5 import java.util.Arrays;
 6 
 7 public class Reflect {
 8     public static void main(String[] args) throws Exception {
 9         /**
10          * 通过Class.forName(String str)方法获取Class实例cls
11          * 通过getConstructor(parameterTypes)获取构造方法
12          * 通过get。。。获取 public的属性， 方法
13          * 通过getDeclared。。。获取public，protected， private属性， 方法
14          * 通过newInstance(parameterTypes)构造对象
15          */
16         Class<?> cls = Class.forName("reflect.Book");
17          Constructor<?> con = cls.getConstructor(String.class, double.class);
18          Object obj = con.newInstance("你好", 2.5);
19          System.out.println(obj);
20          Method[] methods = cls.getDeclaredMethods();
21 //         System.out.println(Arrays.toString(methods));
22          Method setTitle = cls.getMethod("setTitle", String.class);
23           Method getTitle = cls.getMethod("getTitle");
24           // 通过invoke(obj, paramter)执行获取的方法
25           setTitle.invoke(obj, "我好!");
26           System.out.println(getTitle.invoke(obj));
27           System.out.println(obj);
28     }
29 }