利用反射机制操作私有成员变量(private修饰的变量)

利用反射机制操作私有成员变量(private修饰的变量)

主要代码：

package reflection;

import java.lang.reflect.Field;

public class ByReflectionHandlePrivateVar {
    public static void main(String[] args) {
        try {
            //获取HasPrivateVarEntity的类类型(有些人叫做字节码对象)
            Class c  = HasPrivateVarEntity.class;

            //newInstance()实例化对象
            HasPrivateVarEntity hpve = c.newInstance();

            //获取私有成员变量str
            Field field = c.getDeclaredField("str");

            //成员变量name是私有的，所以得先取消语言访问检查  public void setAccessible(boolean flag)
            field.setAccessible(true);

            //给str变量赋值
            field.set(hpve, "---------设置私有对象字符串----------");
            //获得str的值

            String str = (String) field.get(hpve);

            //toString打印: ---------设置私有对象字符串----------
            System.out.println("toString打印: "+str);     


        } catch (InstantiationException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (SecurityException e) {
            e.printStackTrace();
        }
    }
}

---

包含私有成员变量的类

package reflection;

public class HasPrivateVarEntity {
    private String str;

    public String toString() {
        return "HandlePrivateVar [str=" + str + "]";
    }
}