【转】【Java】利用反射技术，实现对类的私有方法、变量访问

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
 
public class Person {
    private String name;//私有属性 
    public String address; 
    public Person(String name){ 
        this.name=name; 
    } 
     
     
    private void setAddress(String address){ //私有方法 
        this.address=address; 
    } 
     
     
    public static void main(String[] args) { 
        try{ 
            Person person=new Person("zhangsan"); 
            Class<Person> cls=Person.class; 
            //获得私有方法 
            Method method=cls.getDeclaredMethod("setAddress", new Class[]{String.class}); 
            //设置私有方法可以被访问 
            method.setAccessible(true); 
            //调用私有方法 
            method.invoke(person, new Object[]{"BJUT"}); 
            System.out.println(person.address);//输出BJUT 
               
            //访问私有变量 
            Field field=cls.getDeclaredField("name"); 
            field.setAccessible(true); 
            field.set(person, "test中国");
            System.out.println(field.get(person));//输出zhangsan 
               
             
            ArrayList<String> test = new ArrayList<String>(1000);
            Class<ArrayList> tcls = ArrayList.class; 
             
            field = tcls.getDeclaredField("size"); 
            field.setAccessible(true); 
            field.set(test, 100);
            System.out.println(field.get(test));
             
            System.out.println(test.size());
             
        }catch(Exception ex){ 
            ex.printStackTrace(); 
        } 
           
    }
     
    public class Test {
        private String name;//私有属性 
    }
 
}