Java中的反射

最新推荐文章于 2021-03-07 11:04:54 发布

原创最新推荐文章于 2021-03-07 11:04:54 发布 · 165 阅读

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#获取私有方法 #私有属性.

假如我们有一个学习的类里面的东西都是私有的

例如:

public class Student {

   private String name;
   private int number;
   private String address;
   public String sex;



   public Student(String name, int number, String address, String sex) {
       super();
       this.name = name;
       this.number = number;
       this.address = address;
       this.sex = sex;
   }

   public Student() {
       super();
   }

   public void show() {

       System.out.println("我是student类的show方法");

   }

   @Override
   public String toString() {
       return "Student [name=" + name + ", number=" + number + ", address="
               + address + ", sex=" + sex + "]";
   }

}

这样就要用到我们的反射了

例如:

public class Test {

   public static void main(String[] args) throws Exception {

       Class<?> c = Class.forName("反射.Student");//获取文件字节码文件
       Constructor cons = c.getDeclaredConstructor(String.class,int.class,String.class,String.class);//获取所有的构造方法
       System.out.println(cons);
       cons.setAccessible(true);//暴力访问
       Object obj = cons.newInstance("张三",10086,"北京市","男");
       System.out.println(obj);

       //获取方法属性
       Method show = c.getDeclaredMethod("show");
       System.out.println(show);
       show.invoke(obj);

       //修改属性里的值
       Field name = c.getDeclaredField("name");
       name.setAccessible(true);
       name.set(obj, "李四");
       System.out.println(obj);

       Field number = c.getDeclaredField("number");
       number.setAccessible(true);
       number.set(obj, 10000);
       System.out.println(obj);

   }

或者我们也可以用第二种方法

例如:

Class<?> c = Class.forName("反射.Student");
       Constructor<?> con = c.getDeclaredConstructor(String.class, int.class,
               String.class, String.class);
       System.out.println(con);
       con.setAccessible(true);

       Object obj = con.newInstance("名字", 10086, "北京市", "女");
       System.out.println(obj);

       // 获得方法的属性
       Field me = c.getField("show");
       me.setAccessible(true);
       System.out.println(me);



       //修改属性
       Field name = c.getDeclaredField("name");
       name.setAccessible(true);
       name.set(obj, "张三");
       System.out.println(obj);