利用java反射机制调用类的私有方法

利用java反射机制调用类的私有方法

1.将getInstance()方法设置为private

public class Singleton {
    private static Singleton instance = null;
    private static synchronized Singleton getInstance() {
      System.out.println("调用 私有的单例!");
           if (instance==null)
                    instance=new Singleton();
             
                    return instance;
      }
     }

 

2.使用反射机制调用getInstance()方法

import java.lang.reflect.Method;

public class test {

    public static void main(String[] args) {

         Class cl = null;
                      try{
                             cl=Singleton.class;
                             Method m1 =cl.getDeclaredMethod("getInstance");

                              m1.setAccessible(true);// 调用private方法的关键一句话
                              m1.invoke(cl);
                        }catch(Exception e){
                              e.printStackTrace();
                        }